Less Wrong is a community blog devoted to refining the art of human rationality. Please visit our About page for more information.

The Fabric of Real Things

13 Post author: Eliezer_Yudkowsky 12 October 2012 02:11AM

Followup toThe Useful Concept of Truth

We previously asked:

What rule would restrict our beliefs to just statements that can be meaningful, without excluding a priori anything that could in principle be true?

It doesn't work to require that the belief's truth or falsity make a sensory difference. It's true, but not testable, to say that a spaceship going over the cosmological horizon of an expanding universe does not suddenly blink out of existence. It's meaningful and false, rather than meaningless, to say that on March 22nd, 2003, the particles in the center of the Sun spontaneously arranged themselves into a short-lived chocolate cake. This statement's truth or falsity has no consequences we'll ever be able to test experientally.  Nonetheless, it legitimately describes a way reality could be, but isn't; the atoms in our universe could've been arranged like that on March 22nd 2003, but they weren't.

You can't say that there has to be some way to arrange the atoms in the universe so as to make the claim true or alternatively false. Then the theory of quantum mechanics is a priori meaningless, because there's no way to arrange atoms to make it true. And if you try to substitute quantum fields instead, well, what if they discover something else tomorrow? And is it meaningless -rather than meaningful and false - to imagine that physicists are lying about quantum mechanics in a grand organized conspiracy?

Since claims are rendered true or false by how-the-universe-is, the question "What claims can be meaningful?" implies the question "What sort of reality can exist for our statements to correspond to?"

If you rephrase it this way, the question probably sounds completely fruitless and pointless, the sort of thing that a philosopher would ponder for years before producing a long, incomprehensible book that would be studied by future generations of unhappy students while being of no conceivable interest to anyone with a real job.

But while deep philosophical dilemmas such as these are never settled by philosophers, they are sometimes settled by people working on a related practical problem which happens to intersect the dilemma. There are a lot of people who think I'm being too harsh on philosophers when I express skepticism about mainstream philosophy; but in this case, at least, history clearly bears out the point. Philosophers have been discussing the nature of reality for literal millennia... and yet the people who first delineated and formalized a critical hint about the nature of reality, the people who first discovered what sort of things seem to be real,were trying to solve a completely different-sounding question.

They were trying to figure out whether you can tell the direction of cause and effect from survey data.


Please now read Causal Diagrams and Causal Models, which was modularized out so that it could act as a standalone introduction. This post involves some simple math, but causality is so basic to key future posts that it's pretty important to get at least some grasp on the math involved. Once you are finished reading, continue with the rest of this post.


Okay, now suppose someone were to claim the following:

"A universe is a connected fabric of causes and effects."

vs.

(In the right-hand image we see a connected causal fabric; the sun raises the temperature, makes plants grow, and sends light into the eyes of the person eating from the plant.  On the other hand, while "post-utopian" is linked to "colonial alienation" and vice versa, these two elements don't connect to the rest of the causal fabric - so that must not be a universe.)

This same someone might further claim:

"For a statement to be comparable to your universe, so that it can be true or alternatively false, it must talk about stuff you can find in relation to yourself by tracing out causal links."

To clarify the second claim, the idea here is that reference can trace causal links forwards or backwards. If a spaceship goes over the cosmological horizon, it may not cause anything else to happen to you after that.  But you could still say, 'I saw the space shipyard - it affected my eyes - and the shipyard building was the cause of that ship existing and going over the horizon.'  You know the second causal link exists, because you've previously observed the general law implementing links of that type - previously observed that objects continue to exist and do not violate Conservation of Energy by spontaneously vanishing.

And now I present three meditations, whose answers (or at least, what I think are the answers) will appear at later points in Highly Advanced Epistemology 101 For Beginners.  Please take a shot at whispering the answers to yourself; or if you're bold enough to go on record, comments for collecting posted answers are linked.


Meditation 1:

"You say that a universe is a connected fabric of causes and effects. Well, that's a very Western viewpoint - that it's all about mechanistic, deterministic stuff. I agree that anything else is outside the realm of science, but it can still be real, you know. My cousin is psychic - if you draw a card from his deck of cards, he can tell you the name of your card before he looks at it. There's no mechanism for it - it's not a causal thing that scientists could study - he just does it. Same thing when I commune on a deep level with the entire universe in order to realize that my partner truly loves me. I agree that purely spiritual phenomena are outside the realm of causal processes, which can be scientifically understood, but I don't agree that they can't be real."

How would you reply?


Meditation 2:

"Does your rule there forbid epiphenomenalist theories of consciousness - that consciousness is caused by neurons, but doesn't affect those neurons in turn? The classic argument for epiphenomenal consciousness has always been that we can imagine a universe in which all the atoms are in the same place and people behave exactly the same way, but there's nobody home - no awareness, no consciousness, inside the brain. The usual effect of the brain generating consciousness is missing, but consciousness doesn't cause anything else in turn - it's just a passive awareness - and so from the outside the universe looks the same. Now, I'm not so much interested in whether you think epiphenomenal theories of consciousness are true or false - rather, I want to know if you think they're impossible or meaningless a priori based on your rules."

How would you reply?


Meditation 3:

Does the idea that everything is made of causes and effects meaningfully constrain experience? Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?


Mainstream status.

Part of the sequence Highly Advanced Epistemology 101 for Beginners

Next post: "Causal Diagrams and Causal Models"

Previous post: "Firewalling the Optimal from the Rational"

Comments (303)

Comment author: Bundle_Gerbe 12 October 2012 09:32:44PM 21 points [-]

I am confused by these posts. On one hand, Eliezer argues for an account of causality in terms of probability, which as we know are subjective degrees of belief. So we should be able to read off whether X thinks A causes B from looking at conditional probabilities in X's map.

But on the other hand, he suggests (not completely sure this is his view from the article) that the universe is actually made of cause and effect. I would think that the former argument instead suggests causality is "subjectively objective". Just as with probability, causality is fundamentally an epistemic relation between me and the universe, despite the fact that there can be widespread agreement on whether A causes B. Of course, I can't avoid cancer by deciding "smoking doesn't cause cancer", just as I can't win the lottery by deciding that my probability of winning it is .9.

For instance, how would an omniscient agent decide if A causes B according Eliezer's account of Pearl? I don't think they would be able to, except maybe in cases where they could count frequencies as a substitute for using probabilities.

Comment author: MBlume 18 October 2012 08:03:17PM *  5 points [-]

OK, let's say you're looking down at a full printout of a block universe. Every physical fact for all times specified. Then let's say you do Solomonoff induction on that printout -- find the shortest program that will print it out. Then for every physical fact in your printout, you can find the nearest register in your program it was printed out of. And then you can imagine causal surgery -- what happens to your program if cosmic rays change that register at that moment in the run. That gives you a way to construe counterfactuals, from which you can get causality.

ETA: There's still some degrees of freedom in how this gets construed though. Like, what if the printout I'm compressing has all its info time-reversed -- it starts out with details about what we'd call the future, then the present, then the past. Then I'd imagine that the shortest program that'd print that out would process everything forward, store it in an accumulator, then run a reversal on that accumulator to print it out, the problem being that the registers printed out from might be downstream from where the value was. It seems like you need some extra magic to be sure of what you mean by "pretend this fact here had gone the other way"

Comment author: thomblake 16 October 2012 06:38:09PM 5 points [-]

For instance, how would an omniscient agent decide if A causes B according Eliezer's account of Pearl?

An omniscient agent would have no reason to decide if A causes B, since causality is a tool for predicting the outcomes of interventions, and the omniscient agent already knows what's going to happen. The concept of "causality" is only useful from a perspective of limited knowledge, much like probability. And the concept of an "intervention" only makes sense in a level of abstraction where free will is apparent.

Pearl addresses this in slide 47 of this lecture. Causality disappears if you consider the entire universe as your object of investigation.

Comment author: [deleted] 16 October 2012 07:17:09PM 1 point [-]

Pearl addresses this in slide 47 of this lecture. Causality disappears if you consider the entire universe as your object of investigation.

I think Bundle's question is just that, given the above, how can Eliezer also say that the universe is actually made of cause and effect?

Comment author: thomblake 16 October 2012 07:39:26PM 0 points [-]

Does Eliezer say that the universe is actually made of cause and effect? Also, what work is "actually" doing in that sentence?

Comment author: Bundle_Gerbe 16 October 2012 08:55:11PM 3 points [-]

"Actually" isn't intended in any sense except emphasis and to express that Eliezer's view is contrary to my expectations (for instance, "I thought it was a worm, but it was actually a small snake").

Eliezer does seem to be endorsing the statement that "everything is made of causes and effects", but I am unsure of his exact position. The maximalist interpretation of this would be, "in the correct complete theory of everything, I expect that causation will be basic, one of the things to which other laws are reduced. It will not be the case that causation is explained in terms of laws that make no mention of causation". This view I strongly disagree with, not least because I generally think something has gone wrong with one's philosophy if it predicts something about fundamental physics (like Kant's a priori deduction that the universe is Euclidean).

I suspect this is not Eliezer's position, though I am unsure because of his "Timeless Physics" post, which I disagree with (as I lean towards four-dimensionalism) but which seems consonant with the above position in that both are consistent with time being non-fundamental. If he means something weaker, though, I don't know what it is.

Comment author: thomblake 16 October 2012 09:01:09PM 0 points [-]

Yes, I think Timeless Physics puts you on the right track, and it should be pretty clear that "causality" doesn't apply so much at the level of comparing possible states of configuration space, aside from perhaps metaphorically to point to which ones are adjacent to which other ones.

Comment author: [deleted] 16 October 2012 07:50:51PM 0 points [-]

Well, if I may take up Bundle's question on his behalf, Eliezer said, in the article to which these are comments:

"A universe is a connected fabric of causes and effects."

and

Does the idea that everything is made of causes and effects meaningfully constrain experience? Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?

Where I take the second quote to imply an endorsement on Eliezer's part of the claim 'everything is made of causes and effects'.

Also, what work is "actually" doing in that sentence?

I don't know, I was quoting (without making that clear) Bundle's phrase.

Comment author: thomblake 16 October 2012 08:52:14PM 0 points [-]

Where I take the second quote to imply an endorsement on Eliezer's part of the claim 'everything is made of causes and effects'.

That was from a koan, and a good one at that. How would one perform an experiment to determine whether the universe operates on causes and effects? It suggests there might be something wrong with the conception that the universe is "made of" causes and effects.

Comment author: [deleted] 16 October 2012 09:03:46PM *  1 point [-]

Maybe, though given the introduction to the article, I think the koan is about the question 'what counts as meaningful?', not 'is the universe made of causal relations'.

But, perhaps more interesting than settling the question of whether or not Eliezer thinks the universe is made of causal relations, we can ask "Is the thesis that the universe is made of causal relations inconsistant with Eliezer's (and your) views on the objectivity of causal relations?'

Given your responses, my dialectical instincts are telling me you think the answer to the above is 'Yes, they are inconsistant, and it is false that the universe is made of causal relations'. Is that so?

Comment author: thomblake 17 October 2012 01:26:52PM 0 points [-]

Given your responses, my dialectical instincts are telling me you think the answer to the above is 'Yes, they are [inconsistent], and it is false that the universe is made of causal relations'. Is that so?

Yes. I thought I actually made that explicit. At least, it's not "made of" causal relations any more than it's "made of" probability.

Comment author: [deleted] 17 October 2012 01:53:04PM *  1 point [-]

Thanks. I think Eliezer is endorsing the 'causal relations are fundamental' reading, and that this apparently conflicts with the idea that causality is the tool of a limited observer. I think he's likely to see these as reconcilable in some way. That, at any rate, is my prediction.

Comment author: Tyrrell_McAllister 15 October 2012 04:28:29PM *  3 points [-]

For instance, how would an omniscient agent decide if A causes B according Eliezer's account of Pearl? I don't think they would be able to, except maybe in cases where they could count frequencies as a substitute for using probabilities.

Indeed. Eliezer motivates causal graphs by pointing to limitations in the observer: It's just not feasible to gather all of the necessary frequencies to do pure Bayesian conditionalization. But that's saying something about the observer, not about the object that the observer is talking about.

We're only talking about causal networks because of our own limitations as epistemic agents. It seems a weird leap to say that reality itself is made out of this stuff (causal networks) that we wouldn't even be thinking about if it weren't for our own imperfections.

Comment author: potato 13 October 2012 07:10:30PM 3 points [-]

It seems to me that this is the primary thing that we should be working on. If probability is subjective, and causality reduces to probability, then isn't causality subjective, i.e., a function of background knowledge?

Comment author: Eugine_Nier 13 October 2012 04:45:26AM *  3 points [-]

Thanks for succinctly articulating what was bothering me about this post. Can't upvote this enough.

Comment author: MBlume 18 October 2012 07:32:40PM *  -1 points [-]

This question seems decision-theory complete. If you can reify causal graphs in situations where you're in no state of uncertainty, then you should be able to reify them to questions like "what is the output of this computation here" and you can properly specify a wins-at-Newcomb's-problem decision theory.

Comment author: adam_strandberg 14 October 2012 02:38:53AM -1 points [-]

An omniscient agent could still describe a causal structure over the universe- it would simply be deterministic (which is a special case of a probabilistic causal structure). For instance, consider a being that knew all the worldlines of all particles in the universe. It could deduce a causal structure by re-describing these worldlines as a particular solution to a local differential equation. The key difference between causal vs. acausal descriptions is whether or not they are local.

Comment author: Eliezer_Yudkowsky 10 October 2012 05:45:46AM 6 points [-]

Mainstream status:

The introduction to causality is intended to be bog-standard. All departures from mainstream academia are errors and should be flagged accordingly.

I can't particularly recall hearing anyone suggest that a universe is a connected fabric of causes and effects in the Pearlian sense of causality. Since Special Relativity there have been many suggestions that a universe is a connected fabric of 'events', or points in spacetime.

I can't particularly recall reading that you can only meaningfully talk about things you can find by tracing causal links (this theory will be developed further in upcoming posts).

Comment author: aaronsw 12 October 2012 12:37:39PM *  19 points [-]

Wolfram 2002 argues that spacetime may actually be a discrete causal network and writes:

The idea that space might be defined by some sort of causal network of discrete elementary quantum events arose in various forms in work by Carl von Weizsäcker (ur-theory), John Wheeler (pregeometry), David Finkelstein (spacetime code), David Bohm (topochronology) and Roger Penrose (spin networks; see page 1055).

Later, in 10.9, he discusses using graphical causal models to fit observed data using Bayes' rule. I don't know if he ever connects the two points, though.

Comment author: private_messaging 03 November 2012 07:44:08AM *  3 points [-]

Few words: CPT symmetry. The causality is just how we model things at macroscopic scale where the time symmetry is broken thermodynamically. At the bottom level, it's relations that have to be true, and to say that value of one variable in a relation causes value of other variable in a relation is either a minor language misuse or a gross misunderstanding arising from such misuse.

Comment author: [deleted] 13 October 2012 06:42:04PM 5 points [-]

When you make this claim about the universe's ontology, it isn't clear whether you mean the is of identity or predication. Are you saying that the things constituting the universe are parts of a connected fabric of causes and effects or that the universe is reducible to causes and effects. The first claim is a standard part of conventional materialism (Pearl's recent contributions notwithstanding). The second claim is one that's set out in Alexander Bird's recent book Nature's Metaphysics: Laws and Properties.

This is a somewhat radical program in that it proposes reducing structural properties to dispositional. Are you or aren't you proposing that (for example) squareness can be reduced to cause and effect.

Comment author: Eliezer_Yudkowsky 15 October 2012 07:30:53PM 1 point [-]

The first claim is a standard part of conventional materialism

Quote? SEP link? As mentioned, I've seen "fabric of events" in SR discussion, no one actually saying "fabric of cause and effect", certainly no Pearl.

Comment author: lukeprog 12 October 2012 06:43:23AM 3 points [-]

Once again speaking as the author of Eliezer's Sequences and Mainstream Academia...

Like Eliezer, I haven't seen anyone suggesting that a universe is a connected fabric of causes and effects in the Pearlian sense. Nor have I seen anyone suggest that one can only meaningfully talk about things that one can find by tracing causal links.

If some young philosopher wants to publish some great, attention-grabbing papers in Nous early in their career, I suggest they write up the philosophy-paper versions of the core ideas in The Useful Idea of Truth and The Fabric of Real Things (citing Eliezer, of course).

Comment author: Mitchell_Porter 12 October 2012 07:02:41AM 7 points [-]

What would it even mean to say that the universe is a fabric of cause and effect "in the Pearlian sense of causality"? Pearl originated a new method of causal analysis, not a new concept of causation.

Comment author: Pfft 13 October 2012 02:48:04AM 1 point [-]

I guess it means causation as manipulability, as opposed to e.g. causation as contrafactual?

Comment author: Eugine_Nier 13 October 2012 04:19:35AM 1 point [-]

How is causation as manipulability "Pearlian"? Pearl's whole point is that it's possible to determine causality without manipulating.

Comment author: pragmatist 19 October 2012 01:24:02AM *  2 points [-]

In so far as Pearl has a theory of causation, it is a manipulability theory. Sure, Pearl provides a method for drawing causal conclusions from data about correlations. But what he means by causation is cashed out in terms of how interventions on one variable affect another variable, not just in terms of correlations. Correlations are indicators of causation for Pearl, but they don't constitute causation. The structural equations Pearl uses to represent causal relationships are meant to capture not just de facto mathematical relations between variables, they support counterfactuals. They tell us what would happen to the variable on the left hand side of the equation if the variables on the right hand side were manipulated.

See section 6 of the SEP article for connections between the manipulability theory of causation and Pearl's formalism.

Comment author: Pfft 13 October 2012 05:09:55PM 0 points [-]

But first you need to know what causality is. While the general idea that "causality is about manipulations" was around before Pearl, he certainly popularized it, and his causal bayesian networks and the do-calculus made it something that could be studied mathematically.

Comment author: thomblake 12 October 2012 07:41:12PM 5 points [-]

"A universe is a connected fabric of causes and effects."

But if you're talking about the entire universe, then there aren't any causes and effects, just as there isn't any time. Causality only shows up when you look at a slice of the system, and whether A causes B or B causes A or they are actually independent can vary based on which slice you choose.

Comment author: sfwc 13 October 2012 12:32:21PM 4 points [-]

On the other hand, while "post-utopian" is linked to "colonial alienation" and vice versa, these two elements don't connect to the rest of the causal fabric - so that must not be a universe.

If I really want to, there's an easy way for me to sidestep this. I just postulate something called "post-consciousness" which is caused both by colonial alienation and by particular arrangements of neurons in the brains of particular people (in a similar way to that in which epiphenomenalists would say consciousness is caused). Presto! A causal chain from my familiar causal fabric to colonial alienation.

In fact, we can add an extra node to any causal diagram without affecting the probabilities of observations only involving the other nodes, by making it an effect of all other nodes but not a cause of anything. By so doing we can connect the diagram up. Thus although we can't subvert the approach in Eliezer's post by postulating an ultimate cause (God), we can always subvert it by postulating an ultimate effect.

What I have said isn't normally a problem in real-life applications of the test `is it part of this connected causal fabric', since very often no such causal connection is postulated. My point is that this test can't in-principle rule out anything. It can only serve as an in-practice test by which we can temporarily rule out objects for which no such causal connection has been postulated.

Comment author: potato 14 October 2012 08:46:56AM *  3 points [-]

I have a plausibly equivalent (or at least implies Ey's) candidate for the fabric of real things, i.e., the space of hypotheses which could in principle be true, i.e., the space of beliefs which have sense:

A Hypothesis has nonzero probability, iff it's computable or semi computable.

It's rather obviously inspired by Solomonoff abduction, and is a sound principle for any being attempting to approximate the universal prior.

Comment author: Psy-Kosh 13 October 2012 01:08:24AM 5 points [-]

Koan 4: How well do mathematical truths fit into this rule of defining what sort of things can be meaningful?

Comment author: dankane 13 October 2012 07:32:30PM 1 point [-]

This seems especially difficult noting that although we can claim that things are caused by certain mathematical truths, it doesn't really make sense to include them in our Bayesian net unless we could say, for example, how anything else would be different if 2+2=3.

Comment author: Peterdjones 13 October 2012 07:37:01PM 1 point [-]

can claim that things are caused by certain mathematical truths

What sort of things?

Comment author: dankane 13 October 2012 08:26:19PM 2 points [-]

Well I know that when I drop something the distance it falls after time t is roughly 1/2 g t^2 where g~10 m/s^2. When I drop something off of a 20m high building, I can reasonably claim that the fact that it takes roughly 2s to reach the ground is a consequence of the above, and of the mathematical truth that 1/2 * 10 * 2^2 = 20.

Comment author: Peterdjones 13 October 2012 08:33:45PM 2 points [-]

where g~10 m/s^2.

That's a physcial truth, and a local one at that. The mathematical expression of a physcial fact is not a "mathematocal truth" because, pace Tegmark, most mathematical truths don't model physical facts. What casues objects to fall is gravity. Maths does not cause it, any more than words do.

Comment author: dankane 13 October 2012 11:52:49PM 2 points [-]

I agree that mathematical truths do not have effects on their own. But when combined with mathematical formulations of laws of reality they do have observable consequences. The timing of a falling projectile above is a consequence of both a mathematical formulation of the law of gravity and a purely mathematical arithmetical fact. If you somehow want to describe the universe without mathematics, good luck.

Comment author: endoself 14 October 2012 10:02:11PM 1 point [-]

That's a physcial truth, and a local one at that.

An event can have more than one cause. My uncertainty about the value of some variable in an equation is related to my uncertainty about the outcome of an experiment in exactly the way that makes Pearlean methods tell me that both the value of t in the equation and the physical truth that g ≈ 10 m/s^2 are causes of the amount of time that the object takes to fall. This is just a fact about my state of uncertainty that falls directly out of the math.

Comment author: Peterdjones 15 October 2012 09:45:09AM 2 points [-]

"Falls out of the math" doens't mean "caused by math" any more than "expressed in math" means "caused by math".

Comment author: endoself 16 October 2012 05:22:55AM 1 point [-]

Sorry, I was unclear. I meant that the causal structure where the equations of physics cause the outcome of the experiment falls out of the Pearlean causal math, not that the outcome of the experiment falls out of the physical math (though the latter is of course also true).

Comment author: Eliezer_Yudkowsky 10 October 2012 05:56:43AM 5 points [-]

Koan 3:

Does the idea that everything is made of causes and effects meaningfully constrain experience? Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?

Comment author: RichardKennaway 13 October 2012 07:50:23AM *  8 points [-]

Physicists tell us that reality is, at the lower levels, described by differential equations. Those describing the temporal evolution of systems are generally hyperbolic differential equations. That is, they have microscopic causal structure: the properties at a point (x,t+dt) depend on the properties only in a small, finite neighbourhood of x at time t. This is what allows larger scale events to be described more abstractly in terms of causal graphs. (A known problem here is the time-symmetry of all these equations. I don't have a solution to that either.)

Some have speculated about the very finest scale being discrete, with fundamental laws of temporal evolution such as those of cellular automata or graph rewriting. That would also provide the fundamental causal structure from which causal structure on the macroscopic level emerges.

A universe whose fundamental laws were all elliptic differential equations -- those in which a change in boundary conditions in one place changes the solution everywhere at once -- would not support causal reasoning. Everything depends on everything else and none of its emergent phenomena would be describable by sparse causal graphs. I'm not sure you could have agents within such a universe, for it to look like anything to them, or any notion of time, but we can imagine such universes from outside.

Comment author: Schpwuette 12 October 2012 04:45:41PM 7 points [-]

Does the idea that everything is made of causes and effects meaningfully constrain experience?

A causally disconnected event would not affect our experience, so no, it does not constrain our experience. But it wasn't meant to: it was meant to constrain our maps, not our experience. To stop us from believing meaningless statements.

Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?

Every causally separated group of events would essentially be its own reality.

Comment author: asparisi 12 October 2012 01:55:59PM 3 points [-]

To answer this, I need to answer another question: What would the universe look like if it did not have the structure of causal models? If I know that then I can know whether or not that universe looks different than ours.

So we're talking about a universe where there is no A --> B causal connections. Where you can't accurately say something like "When I eat, it causes me to be less hungry," or even say anything, since "saying" something requires some sort of causal ability: the ability to push air in intensional patterns.

And that universe... really doesn't look like ours. I might want to talk about a universe where there are correlations but not causations, but then how do I explain the correlations? Are they just brute facts? That seems unlikely. But even in that event, I would expect rules to break down in chaotic ways: one day, food wouldn't make me feel nourished. And it wouldn't be because I ate the wrong foods or something like that, it'd just be because the correlation broke down. And that really doesn't look like our universe either. I may be wet because it was raining, but I don't get wet merely because some 'correlation' between 'sunnyday" and "notwet" broke down.

Comment author: ChristianKl 13 October 2012 01:17:07PM 1 point [-]

So we're talking about a universe where there is no A --> B causal connections.

Actually we aren't. We are talking about an universe where there are effects that happen without cause. That doesn't mean that effects that have causes aren't allowed.

Comment author: asparisi 14 October 2012 05:30:08AM 2 points [-]

Hm. That is conceptually possible, I suppose. Although I can't really imagine how that sort of demarcation criteria would work.

Comment author: CCC 12 October 2012 07:40:11AM 3 points [-]

Yes, to a limited extent I think I can.

A universe without a completely causal structure would have to have a number of effects that have no cause. (This need not apply to all effects in this universe, merely to a subset of effects). The Steady-state universe, a now abandoned alternative to the Big-bang model, may be an example; in the steady-state universe, if I remember correctly, it was theorised that small bits of matter (hydrogen molecules) appeared out of nowhere at random times, at a very low rate. This is an example of an effect without a cause.

Alternatively; consider a universe where a man suddenly appears out of nowhere in the middle of a public area. He claims to be a time traveller, from fifty years in the future, coming back in time to prevent some terrible disaster. Though his story is unbelievable, the disaster he predicts is prevented. Fifty years pass, and the time traveller is not sent back to the past (since the disaster was, after all, prevented). This does not cause a paradox (the laws of this universe are that matter can appear at any time, in any arrangement, including a person with false memories of time time travel from a non-existant future) Such a potential universe thus has an effect (the man appears) without a cause.

Comment author: selylindi 12 October 2012 03:43:04PM *  1 point [-]

The examples don't quite work. In that steady-state universe, the appearing matter subsequently interacts and so is causally connected to the rest of the universe. You just have to trace the connections backwards, and eventually you reach a stopping point. Similarly with the false time traveler: he causally affected the world, so he's clearly part of a chain of causes and effects.

It's a separate question to ask whether everything has a causal in-connection and a causal out-connection. Both your examples, and epiphenomal theories of mind, are meaningfully about unidirectional causal links.

Comment author: CCC 15 October 2012 07:31:42AM 1 point [-]

Hmmm. I had been trying to consider the case where some events have no causes. Now, you're pointing out - as I understand your argument, and please correct me if I am wrong - that the same event can be a cause, and therefore that it is a part of an interconnected causal universe.

This is an interesting argument. If I notice the existance of something, then that is a causal relationship; it exists, and this causes me to notice it by some means. Therefore, anything that I observe shares a causal relationship with the fact of its observation; if that is enough to consider it part of a causal universe, then I can only observe a causal universe. I cannot imagine anything that I cannot, by definition, observe in any manner (including by any deduction) constraining my experience.

On the other hand, I can (at least in certain imagined universes) observe effects without causes; I can observe the time traveller appearing for absolutely no reason.

Comment author: handoflixue 12 October 2012 08:37:27PM 1 point [-]

I had assumed the question was "a universe where an event can have out-connection but not in-connection" (and the consciousness one was about having an in-connection but no out-connection).

In a universe with NO connections, you wouldn't get patterns, much less emergent patterns - no atoms, no stars, no planets, no life, not even internet!

Multiple segregated causal networks would be multiple realities (I think the simplest reference would be to think about two different books or virtual worlds, although there's actually still some connection there)

Individual events which have out-connections but not in-connections, by contrast, seems like a fairly interesting question to explore. Why DO we assume that all evens have in-connections? Why not just assume the weather is because Zeus is mad, and Zeus' emotions are beyond the ken of mortal minds?

Comment author: potato 14 October 2012 09:08:06AM *  2 points [-]

At first thought. It seems that if it could be falsified, then it would fail the criteria of containing all and only those hypotheses which could in principle be falsified. Kind of like a meta-reference problem; if it does constrain experience, then there are hypotheses which are not interpretable as causal graphs that constrain experience (no matter how unlikely). This is so because the sentence says "all and only those hypothesis that can be interpreted as causal graphs are falsifiable", and for it to be falsified, means verifying that there is at least one hypothesis which cannot be interpreted as a causal graph which is falsifiable. Short answer, not if we got it right this time.

(term clarification) All and only hypotheses that constrain experience are falsifiable and verifiable, for there exists a portion of experience space which if observed falsifies them, and the rest verifies them (probabilistically).

Comment author: selylindi 12 October 2012 04:14:30PM 2 points [-]

Several possible examples come to mind for a universe with no cause or effect.

First is a universe with only one thing in it, so that there's nothing for it to be causally connected to.

Second is a universe with multiple things in it that could in principle interact but due to the set-up of the universe never actually do interact. For example, a universe of rigid particles in a void where they would interact if they struck, but the distances between all particles are too great for that to occur in the lifetime of the particles.

Third, a universe in which its entities do interact, but nothing ever changes, so there are no nontrivial correlations. Perhaps count a universe of mutually repelling particles in a void, arranged in an unchanging crystalline structure.

Fourth, more loosely, is a universe in which its entities do interact and change, but the arrangement of all the things is such that only minimal correlations arise. Perhaps a universe analogous to a closed system containing a gas at thermodynamic equilibrium.

Prescinding from those, the idea that everything in our universe is made of causes and effects constrains my expectations in that there should multiple things (check) that actually interact (check) and change (check) and have nontrivial correlations (check). Other than the continuation of such things, I can't readily think of any sense in which the idea constrains my expectations for future experiences.

Comment author: MaoShan 13 October 2012 04:56:21AM *  0 points [-]

To clarify you are pointing out that without cause and effect, stars would not even form, or even baryons for that matter. A gas at thermodynamic equilibrium probably would not be conscious, so from there we can go straight for the Anthropic Principle. Otherwise the question has no real solution--like asking what a peacock would look like if eyes didn't exist. (Handoflixue already killed this horse, though--sorry for beating it.)

Comment author: CronoDAS 14 October 2012 12:47:50AM 4 points [-]

A gas at thermodynamic equilibrium probably would not be conscious, so from there we can go straight for the Anthropic Principle

Any time a theory of cosmology implies that you're a Boltzmann brain, run. ;)

Comment author: The_Duck 12 October 2012 07:48:01AM *  3 points [-]

Does the idea that everything is made of causes and effects meaningfully constrain experience?

No. For any set of observations O1, O2, ..., O_N, you can construct an overprecise causal model that links some central cause to nodes O1, O2, ..., O_N. [That is, our causal model is: "You observed O1 because God willed it. Then you observed O2 because God willed it..."] Thus causal models can explain any set of observations. Constraining experience requires in addition some sort of Occam's Razor that prefers simpler causal models.

Comment author: handoflixue 12 October 2012 08:45:00PM 0 points [-]

Constraining experience requires in addition some sort of Occam's Razor that prefers simpler causal models.

I'd agree with the assertion "Unknowable relationships are equivalent to no relationship". In other words, cause-and-effect is only meaningful if we have some ability to gather information as to the nature of the relationships. Occam's Razor is one such method, but I wouldn't assume that it's specifically required - we could just as easily be born with divine insight as to the cause-effect relationships.

Comment author: Manfred 12 October 2012 05:52:27AM 2 points [-]

How about mild violations of causality?

Comment author: jimrandomh 12 October 2012 06:11:05AM -1 points [-]

Does the idea that everything is made of causes and effects meaningfully constrain experience? Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?

No. I literally assign prior probability zero to the statement that the universe is not made out of causes and effects, because there is causal structure in Turing machines and in all Turing-complete models of computation which could make up the Solomonoff prior. Causal structure is a very broad thing - it's just a sparse graph of interacting entities with a lattice ordering.

I can imagine a universe in which the local ordering I observe doesn't go as far forward or back as I thought, and the true everything-is-causes-and-effects structure is pushed one layer back to something completely hidden from me. I can imagine a universe in which I've falsely inferred an ordering which isn't there, and getting confused by cycles in a graph that I thought was causal. But a universe with no causality at the lowest layer - I think causality is inherent in too many things, and that after subtracting those things there's not enough option space left to make a universe out of.

Comment author: Eugine_Nier 13 October 2012 05:30:43AM 1 point [-]

I can imagine a universe in which the local ordering I observe doesn't go as far forward or back as I thought, and the true everything-is-causes-and-effects structure is pushed one layer back to something completely hidden from me. I can imagine a universe in which I've falsely inferred an ordering which isn't there, and getting confused by cycles in a graph that I thought was causal. But a universe with no causality at the lowest layer - I think causality is inherent in too many things, and that after subtracting those things there's not enough option space left to make a universe out of.

In other words, causality is the invisible pink unicorn.

Comment author: jimrandomh 13 October 2012 07:01:37AM 1 point [-]

In other words, causality is the invisible pink unicorn.

I don't understand this reply at all, except as an indication that I didn't communicate these concepts as well as I'd hoped.

Comment author: Eugine_Nier 13 October 2012 08:16:00AM *  1 point [-]

The text I quoted in the grandparent seems to be saying that even if the universe doesn't contain causality, we can always postulate an external causality structure even if most of it can't be observed.

Comment author: ChristianKl 13 October 2012 01:28:12PM *  0 points [-]

If you can't imagine an universe that's not made out of causes and effects than talking about such an universe is meaningless.

To be able to assign a probability zero to the statement that the universe is not made out of causes and effects you have to be able to imagine a universe that's not made out of causes and effects.

Meaningless statements can't be true or false. Speaking about their probability makes no sense.

Comment author: Eugine_Nier 13 October 2012 09:07:12PM *  2 points [-]

If you can't imagine an universe that's not made out of causes and effects than talking about such an universe is meaningless.

Before Einstein nobody could imagine without universal time either.

In other words, if you can't imagine a universe with property X, that's a fact about you not about the universe.

Comment author: handoflixue 12 October 2012 08:49:31PM -1 points [-]

I think this is one of the few instances where p(0) is actually appropriate! :)

Comment author: Benquo 18 October 2012 08:45:03PM 1 point [-]

There are three alternatives I can think of:

1) The universe has a joint probability distribution such that events are not independent, but so few events are independent that limiting the description to a causal one does not materially reduce the complexity of the "true" model. In this case, There would only be the joint look-up table.

2) All events are independent.

3) The universe is not well-described by the laws of probability.

The first case would make prediction pretty much impossible (since you're never dealing with the exact same set of variables twice). "Same river" and all that. No prediction more specific than "the universe persists in some way" would be true very often on average, since there are so many possible outcomes, and no reason to believe that the next joint probability for the event you care about is similar to the last one.

In the second, you could predict roughly the proportion of events based on the proportion of past events, but there would be no discernible pattern, or result of action.

In the third, I can't tell you what you're likely to observe, for obvious reasons.

Comment author: DuncanS 16 October 2012 10:59:22PM *  1 point [-]

I think it is a mistake to tie the question of what reality is to the particulars of the physics of our actual universe. These questions are about what it is to have an external reality, and the answers to them should be the same whether the question is asked by us in our current universe, or by some other hapless inhabitants of a universe bearing a distinct resemblance to Minecraft.

I can imagine types of existence which don't include cause and effect - geometrical patterns are an example - there are relationships, but they are not cause and effect relationships - they are purely spatial relations. I can imagine living in a universe where part of its structure was purely such spatial relationships, and not a matter of cause and effect.

Comment author: Bundle_Gerbe 16 October 2012 08:03:11PM *  1 point [-]

Imagine a universe that is made only of ideal billiard balls eternally bouncing around on a frictionless, pocketless billiard table. Essentially the same thing as selylindi's idea of a gas in thermodynamic equilibrium. Imagine yourself observing this universe as a timeless observer, or to aid the imagination, that it's "time" dimension is correlated to our space dimension, so we see the system as an infinite frozen solid, 11 by 6 by infinity, with the balls represented by solid streaks inside that go in straight lines except where they bounce off each other or the boundary of the solid.

Now, this system internally has a timelike dimension, except without increasing or decreasing entropy. And the physics of the system are completely reversible, so we have no basis of saying which way is the "future" and which way is the "past" in this system. We can equally well say a collision at one time is "caused" by the positions of the balls one second in the "past" or one second in the "future". There is no basis for choosing a direction of causality between two events.

In our universe, our time is microscopically reversible but macroscopically irreversible, because of the fact that the universe is proceeding from a low entropy state (we call that direction the "past") to a high entropy state (the "future"). I am curious, can anyone coherently describe a universe with nothing similar to irreversible time, but with a useful notion of causation? Or with something like irreversible time, but no causation whatsoever? I have tried (for much more than five minutes!) and not succeeded , but I am still far from sure that it's impossible to do. It might be too much to ask to imagine actually being in a universe without causation or time, but perhaps we can think of how such a universe could look from the outside.

Comment author: dankane 13 October 2012 07:44:50PM 1 point [-]

Well, my experiences could not be readily predicted by a simple Bayesian net. Thus I would expect the joint probability distribution on all things to be really complicated unless there were some other kind of pattern to it. Heck, maybe my experiences correspond to repeated independent samples from a giant multidimensional Gaussian or something (rotated of course so that the natural observable variables have non-trivial covariance).

Comment author: AlexMennen 13 October 2012 07:08:24PM 1 point [-]

Asserting that a particular causal model is an accurate description of the universe certainly constrains experience to fit the causal model. Asserting that it is possible to accurately describe the universe with a causal model is tautologically true because a fully connected model fits every possible probability distribution. Asserting that it is possible to accurately describe the universe with a simple causal structure constrains experience to match a simple causal model. If you know that the universe fundamentally works by running some causal model, asserting that the universe runs this particular causal model predicts that you will never find a more accurate causal model for describing the universe. I'm not sure how asserting that the universe fundamentally works by running some causal model would constrain experience.

Comment author: Scottbert 12 October 2012 06:52:41PM 1 point [-]

I suppose I would say that reality would look as if things happened with no observable pattern related to the things that happen before them, but looking at things requires a long causal chain between photons being emitted and signals in my brain. Supposing I happened to somehow flash into existence for an instant in a noncausal world, or that causality suddenly failed, I would not expect to be able to experience anything past that point since my experiences depend on so many causal processes.

Comment author: byrnema 13 October 2012 01:07:57AM 2 points [-]

An acausal world would be a world where there is experience (some kind of 'reality') but without the possibility of contradiction. It is like a dream, where what you experience is a story and that story can be written over, and can shift, at any moment, without contradiction. So at one moment you see a cup, and then the next moment, you didn't see a cup. It's not that the cup changed or that you were mistaken, it's just that at first your experience was "seeing a cup" and then at the next moment your experience was, "I wasn't there to see that cup". The experiences both happened: You saw it. And you weren't there and didn't see it. It's a string of happenings connected by the word 'and' : I saw a cup and I didn't see a cup and I was there and I wasn't hungry and the grape hurt.

This isn't an original idea, I realize now. I've read of a place like this in at least a couple science fiction stories.

Comment author: RomanDavis 12 October 2012 10:14:29AM 1 point [-]

I would expect not exist in a way that suggests causality, e.i. being born and then expecting death, rather than the other way around. This is hard for me to imagine because I didn't really evolve for that world. It's possible that our universe doesn't work that way at the smallest level, but it seems might suspicious that random events lead to a largest world that operates very deterministically. Still, it is possible that this is just the manifestation of probabilistic laws at the smallest level. It's definitely paying rent so far,(for those who do the experiments) so that's we're going with, and there hasn't been a good argument or experiment against it yet.

Infintesmal "violations" of causal laws as manifestations of probabilistic laws don't seem to effect me very much. Large ones that would pay rent haven't happened on the level that would pay rent on an evolutionary or personal level, and, as I understand it (which is not terribly well) these probably won't happen unless the universe ran from the big bang to heat death a couple hundred times.

I can make models in my head where the universe (on my scale) is really chaotic, but looks deterministic because of a conspiracy by matrix gods or whatever, but that seems to violate Occam's Razor, for what that's worth when matrix gods control your life.

Comment author: Vaniver 12 October 2012 03:21:53AM 1 point [-]

My first answer is that the idea of 'interventions' comes from causality- if I don't like being wet, and it's raining, I can deploy an umbrella, and that will make me not get wet(ter) from the rain. The idea that everything is made of causes and effects meaningfully constrains actions, because an agent that understands causes can manipulate reality better than an agent which doesn't understand causes.

But that's just a further elaboration of what reality looks like now. It's difficult for me to imagine a world without causality- and I don't think that's just because I (like most humans) am a deeply causal thinker. Causal models are just math, and so they can be imagined just like multiple spatial geometries can be imagined, regardless of what the universe's real shape is. I think you would need to have a universe in which no causal models could be justified by the data, which would be an incredibly strange place.

And, actually, by the definition of universe you use in the post, a universe without a causal structure would just be a single node, forever alone.

Comment author: moshez 23 October 2012 11:25:05PM 0 points [-]

Meditation 3: [Hardest of the meditations, for me.] Let us observe the difference between [post-utopian]-->[colonial alienation] and a connected thing (say [I see you picked Ace]-->[You see you picked Ace] from a deck of cards): In the first case, there is no way to settle an argument about whether Ellie is post-utopian or not. We would predict that it would cause arguments between people that are not settled. Anything connected to the causal web is more likely to lead to settlable arguments, at least among people behaving more-or-less rationally. It is not a perfect test, but it does suggest that I expect to see different things from connected networks and unconnected networks, like people changing their minds.

Comment author: folkTheory 17 October 2012 03:47:22AM 0 points [-]

It would be completely random, with all events being equally likely at every point in time. It would have no history, since the past has no effect on the present or future

Comment author: bsterrett 15 October 2012 05:53:16PM 0 points [-]

What is the difference between constraining experience and constraining expectations? Is there one?

Comment author: CronoDAS 14 October 2012 12:44:30AM 0 points [-]

I think that in a universe without a cause and effect structure, we'd tend to see more chaos than we do. Casual models would tend to fail to correspond to reality; all we could do is attempt to reason over joint probability distributions, which, as was explained, is kind of hopeless.

Comment author: [deleted] 13 October 2012 03:30:27PM 0 points [-]

I'm having a hard time making sense of the question. I'm sort of trying to imagine that there are no causal relations, and then opening my eyes to see what's different. Except 'seeing' and 'looking' don't make sense any more. What could it mean for something to 'appear'? I can't get a grip on even the idea of 'experience'.

At which point I conclude that either I am not imaginative enough, or the exercise is inconceivable.

Comment author: [deleted] 13 October 2012 02:51:10PM 0 points [-]

If the universe were not governed by cause and effect, then we could not consistently improve our predictions of the future by observing the past, even by a little bit.

Comment author: philh 13 October 2012 12:44:18PM 0 points [-]

(Written before reading other comments.)

Can you coherently say how reality might look, if our universe did not have the kind of structure that appears in a causal model?

Assuming our universe is causal, then no you cannot. Any universe you can imagine has laws of physics which can be modelled by the interactions of the neurons in your brain, and are therefore causal.

There might be some things that can only be experienced in an acausal universe, but it is not possible for me to imagine them.

Comment author: earthwormchuck163 12 October 2012 09:42:28PM 0 points [-]

In a universe without causal structure, I would expect an intelligent agent that uses an internal causal model of the universe to never work.

Of course you can't really have an intelligent agent with an internal causal model in a universe with no causal structure, so this might seem like a vacuous claim. But it still has the consequence that

P(intelligence is possible|causal universe)>P(intelligence|acausal universe).

Comment author: wedrifid 13 October 2012 12:03:38AM 1 point [-]

P(intelligence is possible|causal universe)>P(intelligence|acausal universe).

That seems plausible but I must admit that I don't know enough details about possible "acausal universes" to be particularly confident.

Comment author: Vaniver 13 October 2012 05:10:26PM *  2 points [-]

If intelligence is seen as optimization power- in the sense of agents that constrain possible futures for their benefit- then it seems clear that the rewards to intelligence are 0 or negative in acausal universes, and so they should be less likely than in universes where they have positive rewards.

Comment author: thomblake 12 October 2012 07:37:17PM 0 points [-]

This one is great - it really does have the contradictory nature of traditional koans.

Just try to picture what you would do to test whether the universe was causal, and how we would adjust our models based on such a test.

Comment author: pragmatist 24 October 2012 12:56:44PM *  4 points [-]

But while deep philosophical dilemmas such as these are never settled by philosophers, they are sometimes settled by people working on a related practical problem which happens to intersect the dilemma. There are a lot of people who think I'm being too harsh on philosophers when I express skepticism about mainstream philosophy; but in this case, at least, history clearly bears out the point.

It's worth mentioning that the first people to rigorously apply Bayes net methods to causal discovery (as far as I know; correct me if I'm wrong) were philosophers. They were the ones who formulated the causal Markov principle. Also, a precursor to the CMC was formulated over half a century ago by another philosopher, Hans Reichenbach. It is true that work of this sort is unrepresentative of what goes on in most philosophy departments (although it's not all that unrepresentative of what contemporary philosophers of science are doing), but as someone who would like to see a lot more of this kind of philosophy, it annoys me a little when this work isn't acknowledged as philosophy done by philosophers.

Comment author: Eliezer_Yudkowsky 10 October 2012 05:50:38AM 2 points [-]

Koan 2:

"Does your rule there forbid epiphenomenalist theories of consciousness - that consciousness is caused by neurons, but doesn't affect those neurons in turn? The classic argument for epiphenomenal consciousness has always been that we can imagine a universe in which all the atoms are in the same place and people behave exactly the same way, but there's nobody home - no awareness, no consciousness, inside the brain. The usual effect of the brain generating consciousness is missing, but consciousness doesn't cause anything else in turn - it's just a passive awareness - and so from the outside the universe looks the same. Now, I'm not so much interested in whether you think epiphenomenal theories of consciousness are true or false - rather, I want to know if you think they're impossible or meaningless a priori based on your rules."

How would you reply?

Comment author: CCC 12 October 2012 07:23:02AM *  7 points [-]

My reply (before reading other replies) is that no, such theories are not forbidden. There is a causal link with the rest of the universe; neurons are causing consciousness. Consciousness, in turn, does not need to cause anything else to be part of the universe; it is part of the universe merely by being caused.

Comment author: Benquo 18 October 2012 08:34:45PM 5 points [-]

If consciousness is epiphenomenal, then what generated your question? I assume you are positing non-conscious people who ask all the same questions about consciousness that we do.

I don't see a reason to rule out neuron-generated epiphenomena a priori - for example, the most elegant explanation of the phenomena might predict some entity that cannot be measured directly, and never affects anything measurable after its generation - but if they existed, we wouldn't notice and wouldn't ask questions about them. Therefore, whatever real thing it is you're asking about cannot be an epiphenomenon.

If true consciousness is an epiphenomenon, then your question is not motivated by experiencing true consciousness. If your question is motivated by experiencing true consciousness, then true consciousness is not an epiphenomenon.

Comment author: DaFranker 18 October 2012 08:43:54PM 1 point [-]

I like your koan responses. They seem like the sort of thinking and arguments that could actually be useful in a discussion, too.

Comment author: Benquo 19 October 2012 03:32:43AM 0 points [-]

Thanks.

It started as a tiny set-piece speech about how consciousness couldn't be an epiphenomenon, which is explicitly what the koan isn't asking about. I had to rewrite several times before it seemed like the sort of thing that might actually engage the questioner.

I'm still not sure I actually answered the koan, though...

Comment author: DaFranker 19 October 2012 02:25:04PM 0 points [-]

I think your answer is very much what the koan was meant to generate. Simply saying 'No, I don't a priori eliminate epiphenomenal theories' seems like it'd miss the point entirely. You tackle the source of the concern or question, and conclude with a very good "If A, B, if ¬A, C" statement that easily follows from your arguments.

More importantly, your answer seems to completely reduce the problem and dissolve the question.

Comment author: jimrandomh 12 October 2012 05:38:23AM 7 points [-]

Does your rule there forbid epiphenomenalist theories of consciousness - that consciousness is caused by neurons, but doesn't affect those neurons in turn?

A forest does not cause trees, and trees do not cause a forest; they are related, but their relation is of a different kind.

However, if you're willing to abuse definitions a little bit, you can pretend that relation is causal; if you define a forest in terms of things like tree-density, then the forest is "caused by" trees, but it's a causal dead-end which affects nothing in turn. The same holds for neurons and consciousness. However, it would be silly to talk about a bunch of trees in the same place which were not a forest, and similarly silly to talk about a working, talking brain without consciousness.

Comment author: ChristianKl 13 October 2012 01:48:59PM 1 point [-]

The debate isn't about whether "consciousness is caused by neurons" is true but whether the specific arguments that Eliezer made in this thread forbid that "consciousness is caused by neurons" and "consciousness doesn't affect neurons" can both be true.

I don't see at all how the argument you are making here has something to do with the rule "For a statement to be comparable to your universe, so that it can be true or alternatively false, it must talk about stuff you can find in relation to yourself by tracing out causal links."

Comment author: Eugine_Nier 13 October 2012 09:02:48PM 2 points [-]

I assume the people arguing that "consciousness is caused by neurons" mean something similar to "the forest is caused by trees" and Eliezer is simply straw-manning/misinterpreting it.

Comment author: RichardChappell 17 October 2012 08:34:35PM 1 point [-]

Nope. Epiphenomenalism is motivated by the thought that you could (conceivably, in a world with different laws from ours) have the same bundles of neurons without any consciousness. You couldn't conceivably have the same bundles of trees not be a forest.

Comment author: earthwormchuck163 12 October 2012 10:12:03PM 3 points [-]

You can account for a theory where neurons cause consciousness, and where consciousness has no further effects, by drawing a causal graph like

(universe)->(consciousness)

where each bracketed bit is short-hand for a possibly large number of nodes, and likewise the -> is short for a possibly large number of arrows, and then you can certainly trace forward along causal links from "you" to "consciousness", so it's meaningful. And indeed for the same reason that "the ship doesn't disappear when it crosses the horizon" is meaningful.

We reject epiphenomenal theories of consiousness because the causal model without the (consciousness) subgraph is more simpler than the one with it, and we have no evidence for the latter to overcome this prior improbability. This is of course the exact same reason why we accept that the ship still exists after it crosses the horizon.

Comment author: moshez 23 October 2012 11:17:55PM 2 points [-]

[Cheating, since I already read some Zombie sequences, but have not read any replies in this thread] The consciousness causes you to speak of consciousness, which is the result of neurons in your brain firing your jaw muscles (and other muscles, and so on). If it was epiphenomenal enough that none would talk about it, we wouldn't have this question in the first place.

[Has consciousness] --> [Writes books/blogs on consciousness]

Causually connects consciousness to the universe.

Comment author: RichardKennaway 12 October 2012 01:58:46PM 2 points [-]

The rule does not rule out epiphenomenalism. It only rules out entities without causal connection in any direction with the material world, and epiphenomenalism says that there is a connection, albeit only in one direction.

Epiphenomenalism is ruled out for other reasons.

Epiphenomena can be considered in terms of causal graphs. Suppose you have two causal graphs proposed to describe some phenomenon. In one, there is a variable called X, with many arrows in and out. The second graph is identical to the first, except that X is renamed to a new variable Y, then X is added back in with a causal arrow from Y to X, and no other arrows impinging on X. Y is stipulated to be unobservable and un-intervenable on, and X to be observable but un-intervenable on in both graphs.

Given these limitations on observations and interventions, is there any experiment that can distinguish between the two graphs? I think there is not.

If not, what does it mean to say that there is such a Y, and that it is Y, not X, that is producing the apparent causal effects of X? It's almost as if at the meta-level, it is Y, not X, that is the epiphenomenon.

Comment author: beoShaffer 12 October 2012 04:57:51AM 2 points [-]

I would say that it isn't ruled out a prior because a causal chain does run from the observable (the neurons) to consciousness.

Comment author: Emile 13 October 2012 04:10:45PM *  2 points [-]

So if Universe A features epiphenomenal consciousness, and Universe B doesn't, and that we consider the statement that we are in universe A and not universe B, then looking back at the rule:

"For a statement to be comparable to your universe, so that it can be true or alternatively false, it must talk about stuff you can find in relation to yourself by tracing out causal links."

These "causal links" you trace out are part of the map, not part of the territory - you have to be able to deduce their existence. And in this case (unlike the spaceship scenario), there is no way anybody can deduce the existence of the neuron -> consciousness link, since by definition nothing can be observed about the consciousness.

=> so, firmly in the "meaningless" camp.

Comment author: MagnetoHydroDynamics 12 October 2012 09:33:21AM 0 points [-]

A one way causal connection cannot be observed. If neurons cause consciousness, but consciousness does absolutely not affect anything else, then there is literally no way to observe consciousness, and so you must in addition to the description of the causal universe include the fact that there are things that are affected by the universe's existence but does not affect the universe, and furthermore that consciousness is one such thing.

A strictly simpler theory is that there is a causal universe, without all that epiphenomea cruft.

Also, the viewpoint of epiphenomenal consciousness is very much triggering my pattern maching of 'human specific inbuilt stupidity'.

Comment author: Eugine_Nier 13 October 2012 04:29:45AM 1 point [-]

How's this different from the case photon leaving my future light cone?

Comment author: dankane 13 October 2012 07:58:32PM 1 point [-]

"For a statement to be comparable to your universe, so that it can be true or alternatively false, it must talk about stuff you can find in relation to yourself by tracing out causal links."

With the above solution, then yes epiphenomenalist theories of consciousness are meaningful. They clearly describe networks in which consciousness connected to the rest of reality that you experience. On the other hand, I think that this is because the above statement fails at its intended goal rather than that these theories are actually meaningful. In particular I think one should append to the above:

"Furthermore, it must not be possible to remove this stuff (and perhaps some other stuff) from your causal network without affecting things that you can experience."

Comment author: GDC3 13 October 2012 05:29:01PM 1 point [-]

It doesn't rule it out. Unless you're directly observing those epiphenominal nodes, Occam's razor heavily decreases the likelihood of such models though, because they make the same predictions with more nodes.

Comment author: philh 13 October 2012 12:58:07PM 1 point [-]

(Written without reading other comments.)

The theory does not forbid a node from having no causal effect on anything else, which is what I think an epiphenomenal consciousness would be. But such a node could not be measured. A logical positivist would say this makes the theory meaningless, and I'm inclined to agree.

Conceivably, if the universe runs on a computer, there could be a node which cannot be measured from inside the universe but could be measured from outside. Perhaps debug info is turned on, and any time neurons fire in patterns that match some regex, the word "consciousness" is printed to stderr. I would not say this is meaningless; if it is true, it gives us a way of communicating with whoever is watching stderr (but no guarantee that such a being exists or would talk back).

But it is not suitable as a theory of consciousness, unless you want to stipulate that neurons write about consciousness for reasons that are completely uncorrelated to consciousness.

Comment author: moridinamael 12 October 2012 07:01:53PM 1 point [-]

Impossible, no; meaningless, yes.

Consciousness in reality causes us to emit sentences about an awareness of subjective experience, so there is a coupling between neurons and the conscious algorithm being run by those neurons.

If consciousness were merely a passive awareness with no causal influence upon anything else in reality, it would not be causally entangled with the universe. This is as close to "meaningless" as I can imagine.

Comment author: The_Duck 12 October 2012 07:45:18AM 1 point [-]

As I read it, the rule does not forbid epiphenomena. Epiphenomena are caused by ordinary things that we can observe, so they are connected to us by causal links, even though we can never discover these links, since epiphenomena do not themselves cause anything we can observe.

This seems like a coherent way the universe could be, but isn't. The machine simulating the universe could constantly scan it for blue objects and populate a list of all blue objects--but without using that list for anything further. This would be an epiphenomal blue-ness tag.

Comment author: Vaniver 12 October 2012 03:43:24AM 1 point [-]

Drill down on "outside the universe," as it seems to conflict with the definition of universe we're using here. Presumably, we mean something which has access to the nodes in the connected fabric of causes and effects, but is not an input to any of them- much like the proposed consciousness. If consciousness is caused by neurons, it's in the fabric, and our omniscient observer will be able to see whether or not consciousness is a node in the fabric or not. We'll avoid the infinite regress by enforcing that all observers are inside the universe / the connected causal fabric, but they are differentiated by where they are in the fabric.

From inside the fabric, we can only comment confidently on the nodes we have access to, and implicitly the nodes which are ancestors of those nodes. Agents like us are both causal ancestors and descendents of each other- we see clear feedback loops that convince everyone of the reality of other agents (barring those confused by solipsism, of course). There could be silent observers (of the consciousness variety or otherwise) that are descendents but not ancestors of the nodes we have access to- and because they're not ancestors of the nodes we have access to, we can't comment confidently on them! But by Occam's Razor, it's generally better to not put such nodes into your model of the universe, since they don't give you any additional predictive or manipulative power, but still cost cognitive resources to lug around.

(It seems to me that a principle that only relies only on the structure of the causal graph which excludes silent observers will also exclude the spaceship that has passed the horizon- and so either we need a principle from outside the model, like "my intuition says spaceships don't disappear but silent observers aren't real," or to put them in the same bin.)

Comment author: Paul_G 21 November 2012 05:38:26PM 0 points [-]

"We can imagine any number of universes, that does not always lead to a good argument. In this case, the main issue with the argument is that while we can imagine that universe, it doesn't look like ours. There's no talk of consciousness, there's no self-reflection. Those are things in reality clearly caused by a link between our thoughts and our brains, one that goes in both directions.

Imagining a world in which people act exactly like people do now, but without a consciousness, strays so clearly outside the bounds of Occam's Razor that there doesn't seem to be any point in thinking about it. Adding in a mysterious 'zombie master' to make the zombies act as though they had consciousness... Well at this point, we're not talking about anything remotely resembling reality. This entire thought experiment in no way gives us any truths about reality whatsoever. It is completely meaningless."

Comment author: CronoDAS 14 October 2012 12:40:07AM 0 points [-]

A strict reading of the rule suggests that it doesn't; consciousness is caused by neurons, and we observe neurons.

Comment author: AlexMennen 13 October 2012 06:52:45PM 0 points [-]

For any precise definition of consciousness that fits epiphenomenalism, it would be meaningful. However, to my knowledge, no such precise definition has been put forward.

Comment author: Scottbert 12 October 2012 06:46:06PM 0 points [-]

Well, my first thought was that it doesn't rule epiphenomenal consciousness out. It's strange that people would still talk about consciousness without it, but you can posit that people are just programmed to talk about consciousness for some reason (it's at least conceivable).

Then I looked at the next guy's answer (asparisi) and thought he had a point: Does our theory of causal links allow for causes to have probabilistic effects? (It's different to say that 'human brains sometimes cause consciousness than to say 'human brains can cause ANYTHING, like a blue goblin appearing in front of you or the universe being destroyed and replaced with another one') I'm not sure. If it does, then epiphenomena-that-sometimes-don't-happen are okay. If not, they aren't.

THEN I thought, but if consciousness is an epiphenomenon then what's strange is that people talk about it at all -- by definition, we cannot be aware of an epiphenomenon. But there could be another cause for the discussion of something we can't interact with in any way. After all, people's talk about gods is not caused by gods. There are other reasons to rule epiphenomena out, but a world with P-zombies is at least conceivable, even if it requires a lot of unlikely assumptions.

Comment author: RomanDavis 12 October 2012 09:56:05AM *  -1 points [-]

I'm not sure. And am not sure how you would you do an experiment to check. My rules aren't data typed into a computer program on which the universe runs, they're descriptions of the universe as experienced through my senses and processed through my mind be things like "inference" and colored by things like the "expectation of beauty", and "Occam's Razor."

The reason I don't believe in the epiphenomenal theory of consciousness is because of the evidence against it, starting with my awareness, the existence of all this talk about awareness, and ending with fuzzier sort of thinking like, "Animals seem awake and aware and aware that they're aware."

Oh, that and saying that consciousness doesn't cause anything you can sense seem a violation of Occam's Razor, while consciousness not effecting anything, ever, even in principle, seems to be a rejection of causality itself.

Comment author: PhilGoetz 23 October 2012 02:15:40AM *  2 points [-]

and yet the people who first delineated and formalized a critical hint about the nature of reality, the people who first discovered what sort of things seem to be real,were trying to solve a completely different-sounding question.

You should give some credit to the logical positivists, because you seem to be trying to re-invent logical positivism. It would be nice to explain how what you're getting into differs from logical positivism.

It would also be nice to do a critical analysis of the refutation of logical positivism. Students today are taught that it's completely discredited. But it was "disproved" by philosophers, which should give one pause. Quine's "proofs" of the principle of ontological relativity, at least, are completely vacuous; and if you do the math, you find that it's false.

Comment author: Eliezer_Yudkowsky 10 October 2012 05:49:27AM 1 point [-]

Koan 1:

"You say that a universe is a connected fabric of causes and effects. Well, that's a very Western viewpoint - that it's all about mechanistic, deterministic stuff. I agree that anything else is outside the realm of science, but it can still be real, you know. My cousin is psychic - if you draw a card from his deck of cards, he can tell you the name of your card before he looks at it. There's no mechanism for it - it's not a causal thing that scientists could study - he just does it. Same thing when I commune on a deep level with the entire universe in order to realize that my partner truly loves me. I agree that purely spiritual phenomena are outside the realm of causal processes, which can be scientifically understood, but I don't agree that they can't be real."

How would you reply?

Comment author: CCC 12 October 2012 07:30:48AM 12 points [-]

My reply, before reading other replies, is that the question is wrongly posed. The described phenomena can be part of a causal universe, because they are causal processes.

Consider the psychic cousin. I draw a card from his deck - it is (say) the three of clubs. Let us further assume that he correctly guesses the card that I have drawn, and does so in 99% of trials. In such circumstances, his statement of the card that I have drawn ('you have drawn the three of clubs!') is caused by my drawing the three of clubs. The mechanism of that causality may not be known, but it is there.

Similarly for the example of "communing on a deep level with the entire universe in order to realize that your partner truly loves you" - there's a causal link, there, and the cause is "your partner truly loves you". (Personally, I'd prefer to check the conclusion by some other means in order to prevent observer bias effects, but this becomes tricky for this example).

Purely spiritual phenomena, therefore, are firmly inside the realm of causal processes, even if they are not yet fully understood.

Comment author: MixedNuts 12 October 2012 09:16:13AM 10 points [-]

"Your partner truly loves you" could also be a purely spiritual phenomenon outside the realm of science. This implies that it has no observable consequences; a partner who truly loves you is no less and no more likely to dump you than one who doesn't. This is an unusual idea of true love.

Comment author: CCC 12 October 2012 10:07:29AM 4 points [-]

It could be. However, the consequences of the questioner's "communing with the universe" are observable; I can observe whether you claim that your partner truly loves you or not afterwards.

Since this is an observable consequence, I therefore conclude that if it is possible to commune with the universe in such a way, and if the results of such communing are correlated at all to the state "your partner truly loves you", then that state has consequences (i.e. whether or not you say that it is true after communing with the universe) and thus can be part of a causal universe.

Comment author: Ender 07 March 2013 09:38:47PM 0 points [-]

And since it has observable consequences, you can do science to it! Yay!

Comment author: Yosarian2 15 January 2013 01:50:47AM 1 point [-]

Right. If there was no causal link between the card drawn and the psychic predicting the card, then the psychic wouldn't get the right answer. There has to be a causal link, or else the psychic answer would have nothing to do with the card that you picked, and then it wouldn't be any better then random.

Comment author: RichardKennaway 12 October 2012 01:36:21PM 8 points [-]

"Magic" just means "I don't know how it works." (Pratchett, somewhere in the Tiffany Aching novels.)

If the world is exhibiting some regularity, you can always ask how that happens. "No mechanism" is itself a prediction: that none will be found. Where did that prediction come from?

Comment author: Vaniver 12 October 2012 03:09:22AM *  7 points [-]

Causal diagrams don't require understanding of the links- if the content of the card influences your cousin's claim, then we would draw an arc from the card to the claim in our causal diagram, even if we don't know how he's influenced by the card.

(Privately, I would suspect the speaker's belief is not rigorous, and would not put much weight by it, but why challenge them on a factual matter when we're discussing causal networks?)

It's not clear to me that you've sufficiently expanded your belief that your partner truly loves you, or what it means to commune with the universe, or what separates physical and non-physical processes. If we define as real things which are part of reality, and acknowledge that your belief in your partner's true love exists in reality, why are we not content to find real causes for that belief?

(Of course, there are many status reasons to turn to spiritual causes. But the instrumental benefits are probably outweighed by the epistemic detriments- or, at least, I should not privately believe their claim, even if I consider it worthy of public endorsement.)

Comment author: asparisi 12 October 2012 02:13:07PM 6 points [-]

Taboo the word real for a moment. Also any related words, like 'actual.' What do you mean when you say that it can be real?

You say your cousin can tell you the name of a card before he looks at it, after a random draw of the deck. But he does it. It's an act on his part. This isn't a mere word-issue either: you don't think the same thing will happen if I try to predict a card you draw from a deck. So you are talking about a direct link between his statement and the card. Unless you think he is doing it by chance (so that there is just a correlation, and an extremely improbable one at that) you think that there is a causal link between the card drawn and the prediction. Saying you don't know what it is, is not the same thing as saying that it is not there.

Likewise, when you say that you commune with the universe, you are stating some act, "communing" and some result "finding out that your partner loves you." You don't expect this to fail the next time you do it, or you wouldn't perform the act to that effect. (You might perform it to "see if it works this time" but that would be another matter.) So I don't think you really believe what you think you believe. Why would you "commune with the universe" if it did not cause effects such as "realizing your partner truly loves you"?

Comment author: Benquo 18 October 2012 08:19:18PM 4 points [-]

I am interested in the idea that what your cousin does happens without a mechanism. Does this mean that the process does not involve your cousin at all? That it happens whether or not your cousin is around? If so, why do you say that it's your cousin who does it?

I could ask the same kind of questions about your communing with the universe, but let's take these things one at a time.

Comment author: jimrandomh 12 October 2012 06:25:18AM 4 points [-]

I agree that anything else is outside the realm of science, but it can still be real, you know. [Two examples with hidden mechanisms]

Mechanisms can be well hidden; if you deny that there is mechanism, you're just cheating yourself out of the chance to figure out what the mechanism was. When you "commune with the universe", you're actually putting your brain into a meditative state where it queries large volumes of remembered weak evidence that you can't recall by normal means. You can use that state for other things, too (but you'll fool yourself if you don't understand its limitations). When your cousin does card tricks, he's explicitly presenting you with a hard puzzle - figure out just how he's cheating. Answers are in books, but custom forbids giving spoilers. Figure it out, and you can fool others the same way.

Comment author: jesch 15 October 2012 01:50:03PM 3 points [-]

If your cousin reliably names my card, it is causally correlated to my drawing the card. I never specified the nature of the casual relationship-whether it's mirrors, marked cards, or the cards whispering in his brain, you told me that my action and his statement are connected. If 'purely spiritual phenomena' have effects, they're causal processes, connected at the very least to your state of mind- if they don't have effects I'm not sure what we're arguing about.

Comment author: Scottbert 12 October 2012 06:26:13PM 3 points [-]

Okay, hypothetical mystic dude.

You said: "IF you draw a card... [then] he can tell you the name of your card". Sounds causal to me! Otherwise he could tell me the name of my card whether I draw it or not!

Also, you commune with the universe TO realize that your partner loves you. If you don't believe the results of your divination are caused by your partner's love why are you doing it?

In short, you may believe you believe that these are 'non-causal processes', but on the level that determines your behavior, you believe they are causal processes. I suspect this is because either labeling these things non-scientific is important to you for some reason (love of mystery, or perhaps it's what your peer group says to believe) or you don't understand what the words 'non-causal process' mean and it's just a password.

Comment author: TheOtherDave 12 October 2012 03:38:10PM 3 points [-]

How would you reply?

Probably I would start with "You say about your cousin that it's not something that scientists could study. That's an interesting claim. Suppose I tried to study it... say, suppose I asked him to demonstrate this ability a hundred times, and wrote down for each demonstration what card I drew, and what card he named. That's one way to start to do science, to observe the phenomenon and record my observations. Would something prevent me from doing that? Would the ability itself stop working? Something else?"

Their answer would give me more of a sense of what I was dealing with. It doesn't engage with the reality question directly, but how I engage with the reality question will depend a lot on their answer to this question.

Comment author: shminux 12 October 2012 05:57:26PM *  2 points [-]

That's one way to start to do science, to observe the phenomenon and record my observations. Would something prevent me from doing that? Would the ability itself stop working? Something else?

Suppose that the Great Psychicator who imbues all psychics with their amazing powers hates Science and revokes their abilities the moment one decides to systematically study them, so all such experiments lead to a null result. This model "explains" the null results found by the James Randi Educational Foundation.

This might look far-fetched, but recall that "Nature" already behaves like it, say in the double-slit experiment. Replace "psychic abilities" with "interference pattern produced by an electron psychically detecting the other slit" and "systematic study" with "adding detector to one of the slits". The moment you start this "systematic study" the electron's "psychic abilities" to sense the presence of the other slit disappear without a trace.

How would you proceed?

Comment author: TheOtherDave 12 October 2012 07:23:38PM 5 points [-]

(nods) This is basically (modulo snark) the position of several people I know who believe in such things, and at least one LW contributor.

Faced with that response, I usually pursue a track along the lines of "Ah, I see. That makes sense as far as it goes, but it gets tricky, because it's also true that we frequently perceive patterns that aren't justified by the data at all, but without systematic study it's hard to tell. For example, (examples)."

Followed by a longish discussion to get clear on the idea that some perceived patterns are indeed hallucinatory in this sense, even though your cousin's psychic power isn't necessarily one of those patterns. This sometimes fails... nobody I know actually claims that all perceived patterns are non-hallucinatory, but some people I know reject the path from "not all perceived patterns are non-hallucinatory" to "some perceived patterns are hallucinatory." Which I generally interpret as refusing to have the conversation at all because they don't like where it's headed. a preference I usually respect out of politeness.

If it succeeds, I move on to "OK. So when I see a pattern that goes away when I begin systematic study, there are two possible theories: either the phenomenon is evasive as you describe, or my brain is perceiving patterns that aren't there in the first place. How might I go about telling the difference, so I could be sure which was which? For example, if I wake up in the middle of the night frightened that there's an intruder in my house, what could I do to figure out whether there is one or not?"

Which moves pretty quickly to the realization that an intruder in my house that systematically evades detection becomes increasingly implausible the more failed tests I perform, and at some point the theory that there simply isn't such an intruder becomes more plausible.

I generally consider this a good place to stop with most people. Lather, rinse, repeat. They have one track that supports "I believe X no matter how many experiments fail to provide evidence for it," and another track that supports "the more experiments fail to provide evidence for X, the less I should believe X". They tend to mutually inhibit one another. The more that second track is activated, the less powerful that first track is; eventually it crumbles.

Comment author: shminux 12 October 2012 07:56:35PM 3 points [-]

an intruder in my house that systematically evades detection becomes increasingly implausible the more failed tests I perform

But things keep disappearing from my house at random! Surely it's an evidence for an invisible intruder, not only for my memory going bad! And this never happens in the office, so it can't be my memory! Therefore intruder!

Comment author: TheOtherDave 12 October 2012 08:26:09PM 2 points [-]

I'm not really interested in role-playing out a whole conversation. If you insist that your invisible intruder, like your cousin's psychic ability, is real and evasive, I look for a different example. If you insist that everything you ever think about, however idly, is real and evasive, I tap out and recommend you seek professional help.

Comment author: shminux 12 October 2012 08:29:02PM 0 points [-]

recommend you seek professional help.

I thought LW was that professional help...

Comment author: satt 13 October 2012 01:16:21PM 3 points [-]

Hmm, my pay slips must be getting lost in the post.

Comment author: ChristianKl 13 October 2012 02:44:35PM 1 point [-]

Which moves pretty quickly to the realization that an intruder in my house that systematically evades detection becomes increasingly implausible the more failed tests I perform, and at some point the theory that there simply isn't such an intruder becomes more plausible.

This assume's that the person you are talking to didn't perform any tests that provide them evidence for their belief. If you are facing someone who got his ideas from reading books, that might work. If you are facing someone who does have reference experiences for his belief, things get a bit different. You are basically telling them that they intruder that they found in their house is a hallucination.

The observer could go and study his cousin systematically. The cousin does 1000 trials and no trial shows any evidence that his cousin isn't psychic. If the observer believes "the more experiments fail to provide evidence for X, the less I should believe X", the huge quantity of experiements dictate to himself that he should believe that his cousin is psychic. The idea that the cousin uses a trick is supposed to become increasingly implausible the more failed tests the observer performs.

Some experiements are obviously systematically flawed. Doing more of those experiments shouldn't lead you to increase your belief. The debate is more more about which experiements are systematically flawed than it's about "I believe X no matter how many experiments fail to provide evidence for it," vs "the more experiments fail to provide evidence for X, the less I should believe X".

Comment author: TheOtherDave 13 October 2012 04:33:51PM 0 points [-]

This assumes that the person you are talking to didn't perform any tests that provide them evidence for their belief.

It doesn't assume this, it infers it about a particular person from the evidence provided by shminux above. The interlocutor shminux is describing rejects the idea that experimental results can be definitive on this question, which is different from the position you describe here. (Anyone who starts out asserting the former, then switches to the latter in mid-stream, is no longer asserting a coherent position at all and requires altogether different techniques for engaging with them.)

The debate is more more about which experiements are systematically flawed

I'm not quite sure what you mean by "the debate".
Is there only one?
That surprises me; it certainly seems to me that some people adopt the stance shminux described, to which I responded.

All that aside, I certainly agree with you that my response to someone taking the stance you describe here (embracing experimentalism as it applies to psychic phenomena in theory, but implementing experiments in a problematic way) should differ from my response to someone taking the stance shminux describes above (rejecting experimentalism as it applies to psychic phenomena).

Comment author: chaosmosis 12 October 2012 06:12:27PM 5 points [-]
  1. How does the Great Psychicator distinguish between Science and normal events? Maybe we can trick it.

  2. This model is more complicated and so it's less probable.

Comment author: shminux 12 October 2012 06:43:09PM 1 point [-]

How does the Great Psychicator distinguish between Science and normal events? Maybe we can trick it.

What would you propose?

This model is more complicated and so it's less probable.

True. But so is Quantum Mechanics vs Classical Mechanics. (Un)Fortunately, CM is not enough to explain what we see (e.g. the interference pattern). To make a parallel with the issue at hand, the null-psychic model alone (without the complicated machinery of cognitive biases) does not explain the many non-scientifically tested claims of psychic powers.

Comment author: chaosmosis 12 October 2012 07:16:33PM *  2 points [-]

A model where people are delusional about psychic powers or making claims about them they don't believe is less complicated than a model with a Great Psychicator because we already know that people are delusional in lots of ways similar to that.

RE: tricking it. The problem is that we can't observe one of the groups involved here, or we invalidate the experiment. But it seems likely to me that all conditions that could prohibit it from working when science is involved would also prohibit the claims about it working from having any basis in reality. In other words, either it can be tricked, or those people making the claims must concede that they don't really have any basis to assert that it works. Any conditions which allow it to prohibit science should also preclude anyone from being justified in making claims about the reasons why it works.

An infinitely complex Great Psychicator would be smart enough to fool our experiments though, I think.

Comment author: shminux 12 October 2012 07:41:02PM *  1 point [-]

An infinitely complex Great Psychicator would be smart enough to fool our experiments though, I think.

Actually, all this entity would have to do is to foil any attempts to go meta on a certain class of phenomena, like psychic powers (and plenty of others, say, homeopathy). In a simulated universe this could be as "simple" as detecting that a certain computation is likely to discover its simulated nature and disallow this computation by altering the inputs. A sensible security safeguard, really. This can be done by terminating and rolling back any computation that is dangerously close to getting out of control and restarting it from a safe point with the inputs adjusted. Nothing infinite is required. In fact, there is very little extra complexity beyond sounding an alarm when dangerous things happen. Of course, anything can be "explained" in the framework of a simulation.

Comment author: thomblake 12 October 2012 07:43:40PM 2 points [-]

In a simulated universe this could be as "simple" as detecting that a certain computation is likely to discover its simulated nature and disallow this computation by altering the inputs.

But mixing "certain computation" and "discover" like that is mixing syntax and semantics - in order to watch out for that occurrence, you'd have to be aware of all possible semantics for a certain computation, to know if it counts as a "discovery".

Comment author: shminux 12 October 2012 08:00:08PM *  1 point [-]

you'd have to be aware of all possible semantics for a certain computation

Not at all. You set up a trigger such as "50% of all AI researchers believe in the simulation argument", then trace back their reasons for believing so and restart from a safe point with less dangerous inputs.

Comment author: thomblake 12 October 2012 08:05:33PM 1 point [-]

You set up a trigger such as "50% of all AI researchers believe in the simulation argument"

If your simulation has beliefs as a primitive, then you can set up that sort of trigger - but then it's not a universe anything like ours.

If your simulation is simulating things like particles or atoms, then you don't have direct access to whether they've arranged themselves into a "belief" unless you keep track of every possible way that an arrangement of atoms can be interpreted as a "belief".

Comment author: chaosmosis 12 October 2012 07:54:48PM *  0 points [-]

Yeah, thanks. This is part of what I was trying to get at. And I'm further contending that if the semantics for every possible scientific experiment were invalidated, then in doing so the hypothetical Great Psychicator would also have to invalidate the semantics for any legitimate claims that psychic powers worked. The two categories overlap perfectly.

This isn't intended to be an argument from definition, I hope that is also clear.

Comment author: moshez 23 October 2012 11:12:57PM 2 points [-]

Replying without reading any of the other answers. Apologies in advance for redundancy:

Meditation 1: The psychic cousin is indeed connected to the network of things. Let's assume that it works, for simplicity, on decks of two cards: an Ace and a King.

Probabilities: Moshe picked Ace/Cousin says Moshe picked Ace -- 0.4 Moshe picked King/Cousin says Moshe picked Ace -- 0.1 Moshe picked Ace/Cousin says Moshe picked King -- 0.1 Moshe picked King/Cousin says Moshe picked Ace -- 0.4

The True Love/Communing is more complicated: Does True Love have any discernible effect? If we assume True Love, say, changes the probability of having a fight (or some property of the fight -- for example, a fight without reconciliation inside of 24 hours), then we should have a diagram:

True Love --> Communing says True Love | | \/ No fight

and resulting joint probability distributions. Since "fighting" is something observable (by a trained psychologist, say, who puts them in the "Love Lab" http://www.gottman.com/49847/The-Love-Lab.html) we have connectedness.

Comment author: earthwormchuck163 12 October 2012 08:59:20PM 2 points [-]

My cousin is psychic - if you draw a card from his deck of cards, he can tell you the name of your card before he >looks at it. There's no mechanism for it - it's not a causal thing that scientists could study - he just does it.

I believe that your cousin can, under the right circumstances, reliably guess which card you picked. There are all sorts of card tricks that let one do exactly that if the setup is right. But I confidently predict that his guess is not causally separated from the choice of card.

To turn this into a concrete empirical prediction: Suppose that I have your cousin repeat his trick several times (say 100) for me, and each time I eliminate any causal interaction between the the deck and your cousin that I can think of. Then I predict with probability ~1 that, within several rounds, your cousin will not be able to guess which card I draw.

If this prediction turns out to be wrong, and your cousin can still reliably guess which card I drew even when we are in lead boxes on opposite sides of the planet, then I will gladly discard my model of reality, since it will have predicted a true state of affairs to be impossible.

Even this wouldn't be enough to prove your cousin's power is acausal, since there are conceivable causal influences that I couldn't eliminate easily.For example, maybe we live in a computer simulation that runs standard physics all the time, except for a high-level override which configures your cousin's visual cortex to a see a picture of every card that anyone draws from a deck. But I would certainly require evidence at least that strong before even considering the possibility that your cousin can guess cards acausally.

it's not a causal thing that scientists could study

A scientist is just a person who learns about things by looking at them (ie causally interacting with them), plus some social conventions to make up for human fallibility. Do you claim that the social conventions of science stop one from learning about this thing by looking at it, or that one cannot learn about this thing by looking at it at all. If the former, then again I confidently predict that you are wrong. If the latter, then I can only ask how you learned about the thing, if not by looking at it.

Same thing when I commune on a deep level with the entire universe in order to realize that my partner truly loves >me.

You mean to say that your confidence that your partner loves you is not a result of your direct interactions with em? How terrible!

Comment author: beoShaffer 12 October 2012 05:13:10AM 2 points [-]

There may or may not be intervening steps, but if your cousins predictions are accurate we can create causal models that either have predictions->card drawn or card drawn->predictions.

Comment author: AnthonyC 12 October 2012 08:52:15PM 1 point [-]

Or Great Psychiator->Card drawn ^ Great Psychiator->predictions

Which might look the same to use here within the universe but is far less likely as a prior.

Comment author: AlexMennen 13 October 2012 06:44:32PM 0 points [-]

Or predictions <-- lurking variable --> card drawn.

Comment author: Dolores1984 17 October 2012 01:43:29AM *  1 point [-]

1: If your cousin can demonstrate that ability using somebody else's deck, under experimental conditions that I specify and he is not aware of ahead of time, I will give him a thousand dollars.

2: In the counter-factual case where he accomplishes this, that does not mean that his ability is outside the realm of science (well, probably it means the experiment was flawed, but we'll assume otherwise). There have been a wide range of inexplicable phenomena which are now understood by science. If your cousin's psychic powers are real, then science can study them, and break down the black box to find out what's inside. There are certainly causal arrows there, in any case. If there weren't, we wouldn't know about it.

3: If your strongest evidence that your partner loves you is psychic intuition, you should definitely get a prenup.

Comment author: hairyfigment 13 October 2012 08:24:59PM 1 point [-]

CCC and others have given most of my answer. As a practical matter, I would ask: 'Do you need to commune with the entire universe in order to realize your partner loves you? If you have no good evidence taken from your relationship, from the interactions between you, that seems like a giant warning sign.'

Note too that the part about the psychic cousin (if we falsely assume that it has a clear meaning which the character wants to state openly) seems meant to describe a graph with a "spiritual" node that connects to the cousin's card-naming behavior and to nothing else that we can observe. Which does not violate this particular rule, but does seem needlessly complicated.

Comment author: GDC3 13 October 2012 05:33:46PM 1 point [-]

Mechanism is beside the point. Mechanism is just causal nodes in between. Having no mechanism just means there is a direct connection.

Comment author: philh 13 October 2012 12:59:04PM 1 point [-]

(Written without reading other comments.)

Let us stipulate that your cousin is indeed psychic. This is not a purely spiritual phenomenon. Then there is certainly correlation between me drawing QH and between him saying "queen of hearts". Probably no direct causal link - I'd guess it has intermediate nodes related to patterns of neurons in his brain - but the graph certainly has a path between the two nodes.

If something does not correlate with anything, then it is not real in the sense that it does not determine your experiences.

Comment author: ChristianKl 12 October 2012 04:14:32PM 1 point [-]

Both cases are quite different. In the first case we have an observation. The cousin can know the name of a card without looking at the card. The observer has no explanation about how the cousin knows. The observer therefore reasons says that cousin has a property P that causes him to know the card.

The moment you call P "being psychic" you add a lot of connotations that have nothing to do with what the observer knows about the process. That added baggage is meaningless.

Case two is about metaphors. The observer engages into an acitivity A to get goal B. Goal B is about having a change in his own belief system that the oberver now believes C. C being that the partner loves her. So the person assumes that there's a clear causal relationship between A and B. Some form of meditation could feel like the observer engages in A and allow him to reach B. There are two struggles: Firstly, the semantics of naming A. Naming A can plausibly help with doing A successfully. Members of this community will probably more comfortable with naming A differently. Secondly there the issue of whether a belief change in my own mind can be "real". That category of claims didn't get yet discussed in this sequence, but I think it makes sense to speak of belief changes as real.


There another issue about this koan. If you ask a buddhist whether they belief that the universe is a connected fabric of causes and effects, they'll answer: "Of course I believe in karma". You don't need to believe in a reductionist worldview to say that the world is made up of cause and effect.

Comment author: Paul_G 21 November 2012 05:28:23PM 0 points [-]

As someone with some experience dealing with this, having learned how difficult it is to fix I would reply something like "You are wrong. If you want to learn WHY you're wrong, tell me and we can work on this together. Otherwise, I'm going to go now."

Playing the game a bit: "Okay, bear with me a moment, this is going to sound a little odd.

I'm not sure what you mean by "outside the realm of causal processes". Does that mean it happens on its own, with no outside influence at all? Nothing causes it, it just... Happens? Even if it's a 'magic' skill, shouldn't he be the one to activate it? I mean, worst case scenario, it's caused by someone drawing a card from a deck. It doesn't happen completely independently of reality, it's CAUSED by something. If your cousin is the only one with this power, I'm sure he could be studied by the scientists and they could figure out what lights up in his brain as he does it.

A minor note, I was once a card magician, and there are very specific ways to either force people to choose the card you want, or to figure out what card they've chosen. I can show you a few, if you want.

Next, 'communing with the entire universe' is a pretty arrogant thing to say, isn't it? I never got any communication, anyway. Question for you - how would it feel to look deeply inwards, ask 'the universe' questions, and receive answers from your own mind? Would it feel much different from what you feel now? Usually it's better to assume that confusing or 'unexplained' things are happening in your mind, not in reality. You FEEL like the universe has told you that he loves you, but that would look exactly the same as if it was just your unconscious mind telling you. How often have people said that they were deeply, permanently in love, but then it didn't work out? Do you really think you're that much better than everyone else?"

Comment author: somervta 16 October 2012 10:11:20AM 0 points [-]

In reality, I would deny the statement about what can be don by his cousin. But for the purpose of this exercise, I would say that if there was truly no causal mechanism, you would have no basis for saying that it was true, because you would have no evidence for it. In fact, you wouldn't even be aware of it. If your cousin can name my card, he does so through a causal mechanism of some kind.

Comment author: RomanDavis 12 October 2012 09:39:50AM *  0 points [-]

Well first of all, we're not perfect philosophers of perfect emptiness. We get our beliefs from somewhere. So it's true that all sorts of things are true that we have no evidence of. For instance, it's very, very likely there's life outside our solar system, but I don't have any evidence of it, so I act as if it's not true because in my model of the universe, it's very unlikely that that life will affect me during my natural lifetime.

I would even go far as to say that there may be matter beyond the horizon of the matter that expanded after the big bang, or that we're all running on an alien matrix, or that God is real but he's just hiding, and I act as if it's false. Not because they're untrue, or unlikely to be true, as I have no way to tell. But because I am very, very unlikely to ever, ever get evidence about any of those things, and they probably will never, and probably could never (especially in the near future) affect me. Not so much a "Nuh uh," as a "So what?"

You know your partner loves you based on evidence. If you have no evidence (from past experience or otherwise), then you are very likely wrong. Love operates according to mechanisms, and we understand some of those mechanisms.

Similarly, just because you don't understand the mechanism by which your psychic cousin works, doesn't mean there isn't one. He could be getting unbelievably lucky, or he could be playing a trick, or there could be things we don't know yet that really truly give him psychic powers. You don't know what the mechanism is, but you haven't really investigated either, have you? Even if you never find out what the mechanism is, how much evidence is that that there is no mechanism?

Lastly, I'm not sure, "no mechanism" even makes sense. What does it mean for something to have no mechanism? What does a thing that doesn't have a mechanism look like? How would you tell?

So, from the top: A Priori, Making Beliefs Pay Rent, No One Knows What Science Doesn't Know, What is Evidence?, Fragility of Value (Why something is unlikely to be true without evidence of it), Uh what was that one about you failing the art and not the other way around?, and Not Even Wrong.

Comment author: Blueberry 23 October 2012 07:00:04AM 1 point [-]

it's very, very likely there's life outside our solar system, but I don't have any evidence of it

If there's no evidence of it (circumstantial evidence included), what makes you think it's very likely?

Comment author: MugaSofer 23 October 2012 01:29:38PM *  2 points [-]

I assume they meant direct evidence. It's truth or falseness do not affect us, we must extrapolate from our knowledge of the structure of the universe.

Comment author: CronoDAS 14 October 2012 12:36:30AM *  -1 points [-]

How would you reply?

In real life?
"You're a loony."
::walks away::

I suspect that's not the answer you're looking for, though. ;)

Comment author: chaosmosis 12 October 2012 07:17:48AM *  -3 points [-]

You know the second causal link exists, because you've previously observed the general law implementing links of that type - previously observed that objects continue to exist and do not violate Conservation of Energy by spontaneously vanishing.

False, I have never observed that objects don't spontaneously vanish when they're out of my range.

Comment author: MixedNuts 12 October 2012 09:10:33AM 5 points [-]

Wanna play Peek-a-boo?

Comment author: chaosmosis 12 October 2012 05:57:16PM *  0 points [-]

I mean something different by "out of my range" than "out of my direct sensory experiences". I mean more that they're such that I can never have experiences from which I can deduce the existence of those other objects out of my sensory experiences. I do believe that objects outside of my sensory experience exist, but I don't believe that objects which are so far away I can never interact with them either directly or indirectly exist. If they do exist, they don't do so in any meaningful way.

Comment author: MixedNuts 12 October 2012 08:34:49PM 8 points [-]

Your beloved daughter tells you she wants to leave on a ship to found a colony outside your future cone. I claim that there is a meaningful difference between "She'll keep existing, so it's sad I'll never see her again but I'm proud she's following a cool dream" and "She'll pop out of existence, why does my daughter want to die?".

Comment author: wedrifid 20 October 2012 08:19:50AM *  3 points [-]

False, I have never observed that objects don't spontaneously vanish when they're out of my range.

A convenient implication of the "things past the Cosmological Horizon don't exist anymore" belief occurs to me. All it takes to utterly annihilate any enemy you have is a fast ship. Fly as fast as you can away from them and poof, you've caused them to cease to exist! The "Ignore Them And They Will Go Away For Real" doomsday device.

Comment author: chaosmosis 20 October 2012 07:48:06PM *  1 point [-]

You're trying to come up with examples of my belief that seem silly, instead of focusing on rational arguments. You're so focused on this goal that you ignore that flying beyond the Cosmological Horizon solves your problem even under your interpretation. If your enemies can never get you ever again, then isn't it safe to say you've ended the war? Why would you be upset that your enemies exist somewhere in some other impossibly far away region of the galaxy, how would this be any different than having destroyed them or banished them to a different dimension?

Comment author: Eugine_Nier 24 October 2012 02:59:45AM *  1 point [-]

Depends, are you trying to escape your enemies or to punish them?

Comment author: faul_sname 23 October 2012 06:14:03AM 0 points [-]

Works for you. They really can't come after you.

Comment author: TimS 20 October 2012 01:11:03PM 0 points [-]

Lightcone only makes sense as a concept if FTL is impossible. If impossible, you can never get far enough away to get the enemy outside your lightcone (without cooperation from your enemy). If possible, the limit of what you could ever see / interact with is unconnected from speed of light.

Comment author: wedrifid 20 October 2012 08:19:54PM 1 point [-]

Lightcone only makes sense as a concept if FTL is impossible. If

Yes, which universe do you live in? FTL is impossible in this one!

Comment author: TimS 20 October 2012 08:22:57PM 0 points [-]

If FTL is impossible, then so is your travel-to-get-enemy-out-of-lightcone scenario.

Comment author: wedrifid 20 October 2012 09:07:48PM 6 points [-]

If FTL is impossible, then so is your travel-to-get-enemy-out-of-lightcone scenario.

No. This is actually a curious feature of living on an expanding universe. If you travel far enough away from something the expansion will be sufficient for light to be unable to reach it. My future light cone as of {now} actually contains things that my future light cone as of {now} does not. The status of the matter that has been taken out of our reach like that is the focus of the discussion.

Comment author: TimS 22 October 2012 08:01:52PM 1 point [-]

Ok, I've thought about it, and I'm still confused about the terminology.

Suppose Alice and Bob agree to try to escape each other's lightcone - so they start traveling away from each other at .5c (relative to the resting frame they started in). I'm a lawyer and can't do the transformations, but I know that the speed Alice perceives Bob traveling at is less than c - let's call that speed X.

If Alice breaks the agreement, turns around, and starts traveling towards Bob at a speed greater than X (relative to the mutual starting frame), she'll eventually catch up with Bob.

Given that, either (a) I've made a mistake about how relativity works, or (b) it seems impossible for Bob to get outside of Alice's lightcone. Please help.

Comment author: MagnetoHydroDynamics 12 October 2012 09:39:49AM 1 point [-]

You have observed that objects tend conserve energy. You have also observed that the cosmological horizon isn't absolute, but is in fact centered on you. You have also observed that time is symmetric (charge and parity flipped). You have observed that a model of the universe without any absolute coordinates is more likely. Thus we induce that were you put on a spaceship, you would never cross the cosmological horizon, from your own point of view. Similarly it is very likely that some other person would have the same experiences.

Q. E. D(?)

Comment author: chaosmosis 12 October 2012 05:49:57PM *  -1 points [-]

You have observed that objects tend conserve energy.

Objects inside the cosmological horizon are the ones I observe tend to conserve energy.

You have also observed that the cosmological horizon isn't absolute, but is in fact centered on you.

I think you said this backwards, or else I don't know what you mean by saying the horizon is centered on me.

You have also observed that time is symmetric (charge and parity flipped).

I don't know what you mean by this.

You have observed that a model of the universe without any absolute coordinates is more likely.

Your terminology is unfamiliar to me.

Thus we induce that were you put on a spaceship, you would never cross the cosmological horizon, from your own point of view.

I'm uncertain how we induce this from the previous statements.

Similarly it is very likely that some other person would have the same experiences.

I can't agree to this statement until I understand the ones previous to it.

My overall impression of your arguments is that you made the same argument over again, just using more complicated terminology and breaking it down into smaller parts. I think my initial line of argument stands against this sort of attack. Everything that I know is derived from my experiences. By definition I cannot have had experiences or been effected by things outside the cosmological horizon. Therefore I cannot know anything about what happens outside the cosmological horizon.

Things don't exist in any meaningful sense except a relational one. Yudkowsky's arguments here seem reminiscent of certain Kantian concepts or of Plato's idea of eternal forms, and those sort of arguments have always annoyed me. It's useless to make predictions or judgements about things that you will never encounter in any way. I don't understand why it's so important to Yudkowsky to insist that we can know things about the universe external to ourselves. Even if we could, so what? Why would I even care?

Comment author: CCC 19 October 2012 05:59:34PM *  3 points [-]

You have observed that objects tend conserve energy.

Objects inside the cosmological horizon are the ones I observe tend to conserve energy.

Yes, exactly.

You have also observed that the cosmological horizon isn't absolute, but is in fact centered on you.

I think you said this backwards, or else I don't know what you mean by saying the horizon is centered on me.

The cosmological horizon is defined in terms of a distance from a given observer. It is the distance beyond which you cannot observe anything, due to the expansion of the universe.

You have also observed that time is symmetric (charge and parity flipped).

I don't know what you mean by this.

If you run the universe backwards, flipping all charges (positive to negative and vice versa) and parity (like a mirror image of the universe, I think) then the laws of physics, as we know them, remain unchanged at the atomic level. (Don't ask about all those eggs suddenly unscrambling in this reversed universe).

You have observed that a model of the universe without any absolute coordinates is more likely.

Your terminology is unfamiliar to me.

This is one of the foundational assumptions of relativity - that there is no absolute rest frame. That a set of coordinates using any one non-accelerating object as the origin is just as useful as the set of coordinates using any other non-accelerating object as the origin; you can use the same equations to describe the universe, regardless of the velocity of the origin. (Note that the acceleration of the origin still has an effect). For argument in support of this point, I recommend "On The Electrodynamics of Moving Bodies" by A. Einstein (it's more readable than most people think).

Thus we induce that were you put on a spaceship, you would never cross the cosmological horizon, from your own point of view.

I'm uncertain how we induce this from the previous statements.

  • Accelerate the spaceship to near-lightspeed, then shut off the engines and coast along
  • Define a reference frame using the (now non-accelerating) spaceship as the origin. The spaceship thus remains at the origin - it does not move. (Note that in this reference frame, the Earth is moving backwards at pretty close to the speed of light).
  • Recall that the cosmological horizon is defined in terms of a distance from yourself. In this newly defined reference frame, it is not moving. Nor is your spaceship.
  • Hence, the spaceship will never cross your cosmological horizon (though it will eventually cross Earth's cosmological horizon)

Similarly it is very likely that some other person would have the same experiences.

I can't agree to this statement until I understand the ones previous to it.

Quite. I hope this helps.

Comment author: chaosmosis 20 October 2012 06:38:42AM *  2 points [-]

My confusion was a result of me not recognizing that the Cosmological Horizon would be different if two people existed in different locations. It was also a result of taking a post-warp perspective instead of one which would apply equally well both post and pre warp, which caused me to misunderstand the way that some of those arguments were meant to function.

I don't think the point about absolute coordinates was relevant, or else I still might be misunderstanding it. The position I'm trying to defend doesn't say that "nothing exists outside of me", it takes a more agnostic approach and says that I shouldn't bother trying to decide whether things exist outside of me or whether or not I'm justified in assuming that everything there is the same as here. I don't say that the universe actually has a giant sphere built into it, centered on me; I just contend that I don't know anything about things that I'll never interact with and that I'm not much interested in them.

Thank you very much, you definitely helped.

Comment author: wedrifid 19 October 2012 08:20:55PM 2 points [-]

Thus we induce that were you put on a spaceship, you would never cross the cosmological horizon, from your own point of view.

I'm uncertain how we induce this from the previous statements.

The Cosmological Horizon was named well. It's a horizon. Walk a couple of hundred miles and look again and the horizon is still going to be just as far away as you started. (This is without even considering living on a planet that is expanding at an accelerating rate.)

I don't understand why it's so important to Yudkowsky to insist that we can know things about the universe external to ourselves. Even if we could, so what? Why would I even care?

You don't have to care about most of physics. Get an intuitive grasp on Newtonian physics, take it on faith that the guys who made your GPS know something about something called "Relativity" and you are set. Oh, and if folks invent space travel sufficiently powerful that horizon issues come into it don't start acting as folks who are going to be far away are going to die just because at some time in the future it will be theoretically impossible to contact them. That could get awkward and make straightjackets necessary.

Comment author: chaosmosis 20 October 2012 06:30:15AM 0 points [-]

Oh, and if folks invent space travel sufficiently powerful that horizon issues come into it don't start acting as folks who are going to be far away are going to die just because at some time in the future it will be theoretically impossible to contact them. That could get awkward and make straightjackets necessary.

This argument begs the question by assuming that it is morally wrong to not value the lives of people who are functionally abstractions, which is the assumption that I am questioning. Because of vagueness, I'm unsure whether or not this would be accurate, but I also get the feeling that you might be conflating convenient societal conventions with actual individual moralities.

Comment author: wedrifid 20 October 2012 08:12:37AM 0 points [-]

This argument begs the question by assuming that it is morally wrong to not value the lives of people who are functionally abstractions, which is the assumption that I am questioning.

No it doesn't. It expresses a position. One that is a necessary exception to the "well I suppose you don't need to understand or care about physics if you really don't want to" concession I had made in the preceding statements. It does convey the message that you disagree with---that physics doesn't care about your disbelief, your sister in a long long time and a galaxy far away is an artifact of the same physics that your are made of and thereby it rejects "Why should I even care?" as an anomaly rather than a default.

For the purpose of the discussion your actual morality is barely relevant and a "prefer my sister to be alive assuming she actual was real according to the physics we operate on" morality is assumed merely for the sake of convenience. If you really want you can outright hate your counterfactual sister, in which case not murdering her could be the mistake you make. Or, you could conceivably construct a utility function that values configurations of the universe only when they happen to be spatially located sufficiently near to the future-object you call "you". That allows you to "just not care" about such things.

I infer, by the way, that you don't value anything in the universe after the time of your death. Some people (claim that they) have such a value system. For you it is implied because "outside your future light cone" isn't defined if you don't exist. As an illustration consider your brother flying at near light speed in the opposite direction to your sister. You can choose, if you follow your brother in your relativistic rocket you can keep him within your future light cone but lose your sister. If you follow your sister then you lose your brother. If you are dead then your utility function doesn't specify which sibling you followed and sophistmagically allowed to remain 'real'.

I suppose you could propose a hack to your utility function such that when you die the "stuff that matters and is considered real" part of reality could become fixed to "stuff that is within the light cone of you at the time of your death". But then that would imply that your sister and brother are both 'real' but that they aren't 'real' to each other.

Because of vagueness, I'm unsure whether or not this would be accurate, but I also get the feeling that you might be conflating convenient societal conventions with actual individual moralities.

Not remotely. Merely assuming one of the must uncontroversial of societal conventions (and human instinct) out of (perceived) convenience. Again, your morality, ethics and values can be as arbitrary as you like for the purpose of this conversation.

Comment author: chaosmosis 20 October 2012 07:44:25PM *  0 points [-]

I understand that morality and physics are different, but I think you might underestimate the connection. My personal epistemology says that in order to avoid an infinite regress we need to place some sort of foundation on our concept of what is true or not. I use my internal values as this foundation, and only consider a concept to be true or meaningful if that concept achieves my values, whether directly or indirectly. I don't think this is as unreasonable as you like to portray it.

Concepts which do not pay rent do not exist for me; I don't bother wasting my time or cognitive space pondering their existence or nonexistence. Believing in the existence of physics outside the Cosmological Horizon doesn't do anything useful for me, because it doesn't lead me to make any new predictions about what my experiences will be. The only reason it would possibly matter to me is if I valued peoples' existence as an abstract thought rather than as a tangible interaction. Even then, I don't think it would deserve the status of a truth, it would be more of a convenient fiction that it makes me feel happy to believe in.

When you talked about future societies that have to deal with problems related to the horizon, and said that those societies would need to have a rule saying they should believe in the existence of people beyond their horizon, that is what I felt was conflating convenient societal convention and individual morality.

Comment author: wedrifid 20 October 2012 08:29:31PM *  0 points [-]

Concepts which do not pay rent do not exist for me

You keep saying that. I still reject the premise. This is not a correct usage of the local jargon "pay rent". Use a different phrase.

Comment author: chaosmosis 20 October 2012 09:44:35PM *  1 point [-]

What predictions are you lead to by these concepts?

Comment author: drnickbone 20 October 2012 10:37:51PM *  0 points [-]

It's true, but not testable, to say that a spaceship going over the cosmological horizon of an expanding universe does not suddenly blink out of existence

This example has been used by Eliezer before in the Sequences, and it is a bit problematic under the latest physical theories. Assuming cosmological horizons behave like black hole event horizons, the theories say the following:

  1. The spaceship doesn't "blink out of existence"; instead it becomes more and more red-shifted, and never crosses the horizon from our own point of view.
  2. Further, in a quantum mechanical picture, the state of the spaceship eventually returns from the horizon, greatly scrambled, in the form of Hawking radiation. This happens within a finite proper time, as measured by the spaceship's clocks.
  3. Worse, if the spaceship also manages to cross the horizon (i.e, the clocks keep ticking from its own point of view) and continues to exist in some region "outside", then its informational state becomes duplicated. But this is a violation of unitary evolution in quantum mechanics. It's sometimes called the "xeroxing" paradox.

Accordingly, anyone taking a trip on that spaceship shouldn't be at all confident they'll reach anywhere!

But there is an interesting (and rather worrying) follow-through to this reasoning. In cosmology, we observe something very like a positive cosmological constant (lambda term) pushing galaxies apart at an accelerating rate. If it continues to behave like a cosmological constant, then every galaxy in the universe is exactly like the spaceship, and will eventually red-shift into a cosmological horizon with respect to every other galaxy. It apparently follows from this that every galaxy in the universe (including our own) can only continue to exist for a finite proper time before getting scrambled into Hawking radiation. So we're not actually any safer staying on Earth than going off in the spaceship! This "end-of-time" effect has been discussed in a number of recent papers including this one by Raphael Bousso: the predicted end is in about 5 billion years. Needless to say, the effect is extremely controversial, as is the chain of reasoning leading to it. But if there is something wrong with the reasoning, it's not clear where...

Comment author: Eliezer_Yudkowsky 20 October 2012 10:46:14PM 2 points [-]

Assuming cosmological horizons behave like black hole event horizons

Why on Earth would they?

Edit: Also that paper does not say anything about cosmological horizons converting anything into Hawking radiation! It's an entirely different and stranger argument.

Comment author: pragmatist 21 October 2012 04:08:26PM *  5 points [-]

Why on Earth would they?

In asymptotically flat spacetimes, the event horizon of a black hole is defined (roughly) as the boundary of the region of spacetime that can be seen by an immortal observer (more precisely, it's the boundary of the causal past of future null infinity). If you extend this definition to generic spacetimes, then it applies to the cosmological event horizon in a spacetime with positive cosmological constant. Because of this formal similarity, a number of results in black hole thermodynamics (specifically, the laws of black hole mechanics) can be generalized to the cosmological horizon.

Anyway, one response (Susskind's) to the sort of thing drnickbone brings up, in the case of black holes, is black hole complementarity. We seem to have this paradox when something falls into a black hole. On the one hand, we don't want information to disappear beyond the event horizon, so the information must be absorbed into the event horizon itself, theoretically readable off the structure of the horizon (or off Hawking radiation). On the other hand, from the perspective of an infalling observer, nothing special happens as she passes through the horizon. It certainly doesn't seem to her as if the information she carries has been smeared over the event horizon. Susskind's response is essentially that both of these things happen. The information is both reflected and transmitted by the event horizon. But the no-cloning theorem rules out the possibility that the reflected and transmitted information are two separate things. Instead, they are the same event described from different perspectives.

From an outside observer's perspective, the information is painted onto the horizon. From an infalling observer's perspective, the information passes right through the horizon. Extending this idea to the cosmological horizon and a spaceship leaving my horizon: From the perspective of the spaceship nothing special has happened. After all, why should they care about my horizon. From my perspective, once the spaceship hits the horizon, all the information constituting the spaceship is now smeared over the horizon. And of course, if I am to abide by the no-cloning theorem, I cannot simultaneously maintain that the spaceship continues to travel past the horizon. From my perspective, the spaceship does cease to exist (except as information encoded in the structure of the 2-dimensional cosmological horizon).

[ETA: I should have mentioned that this isn't just completely baseless speculation on Susskind's part. He bases his claim on an argument from string theory. The basic idea is this: The spatial extent of a string's wave function depends on the "resolution time", which is the time scale over which observations are made. As this time scale gets smaller and smaller, i.e. as our observations get faster, the spatial extent of the string gets larger. As long as the resolution time is significantly larger than the Planck time, the effect of this phenomenon is negligible. Now think of someone falling into a black hole while making measurements on a string. Another observer is outside the black hole looking on. The infalling observer's resolution time won't change as she falls. But the outside observer's resolution time will effectively get smaller and smaller, due to gravitational time dilation. As a consequence, the string gets bigger and bigger from his perspective. As the falling observer hits the event horizon, the string is big enough to be spread across the entire horizon, which means the information it contains is now spread across the event horizon. So from the outside observer's perspective, the string never falls into the black hole; it gets smeared across the horizon and the information is eventually radiated out. And since the infalling observer is also made of strings, she unfortunately gets spread across the horizon too. But none of this holds in the infalling observer's perspective. The string doesn't grow in size -- it remains localized and falls through the event horizon into the singularity. So, very speculative, but not baselessly so.]

Comment author: drnickbone 28 February 2013 01:09:22PM 2 points [-]

On the one hand, we don't want information to disappear beyond the event horizon, so the information must be absorbed into the event horizon itself, theoretically readable off the structure of the horizon (or off Hawking radiation). On the other hand, from the perspective of an infalling observer, nothing special happens as she passes through the horizon. It certainly doesn't seem to her as if the information she carries has been smeared over the event horizon. Susskind's response is essentially that both of these things happen.

An update. I didn't realise this a couple of months ago, but it seems there has been a big controversy brewing recently about black hole complementarity, and whether it is consistent. There was a key paper by Polchinski and three others in August Complementarity or Firewalls?; see also his guest post in Discover.

The basic argument is that there is a new black hole paradox: quantum states on the edge of a horizon have to be fully entangled BOTH with Hawking radiation that has already emerged from the black hole AND with neighbouring states that are just inside the black hole. And that is not possible, because there is a "monogamy" of quantum entanglement. Further, complementarity doesn't help, because an observer could in principle collect the entangled radiation that had already emerged from the black hole, distill it, and then bring it into the black hole to meet its duplicate entangled state inside, which would lead to quantum cloning. Oops. Instead Polchinksi et al propose that there is a "firewall" at the black hole event horizon which would destroy the second entanglement, and also destroy any observers going into the black hole.

There seems to have been a big fight on the high energy physics archive, with lots of authors drafting papers in an attempt to refute Polchinski et al, then withdrawing them or heavily editing them. Bousso also had a go, claiming that they had misunderstood complementarity, then retracted; his latest version argues that they've found a genuine paradox after all.

To be fair, not many of these physicists/cosmologists agree with the firewall solution, probably because it can leads to observers suddenly disappearing into flame without warning (it is possible to reach an event horizon around a very large black hole in otherwise normal space, with no outward-sign that is coming, then smash into the firewall and die). That violates the same sorts of physical intuitions that Eliezer raises in the main article (and which I challenged). It's also not clear exactly when a firewall forms (if it does) or if there are firewalls at cosmological horizons.

Worth watching for more developments.

Comment author: drnickbone 22 October 2012 09:19:29PM *  0 points [-]

P.S. I found the following interesting paragraph in Bousso et al which considers Susskind's complementarity proposal. It seems to make a big difference whether you define an observer first (and then consider his causal horizon), or define a causal patch first (together with its horizon) and then consider where the observer might be:

In the traditional discussion of black hole complementarity, one picks an observer and constructs the associated causal patch. It is impossible, by construction, for an observer to leave his own patch. In other words, time cannot end if we live in a causal patch centered on our own worldline. In eternal inflation, however, one first picks a causal patch; then one looks for observers in it. Some of these observers will be closer to the boundary and leave the patch sooner than others, who happen to stay in the patch longer. Equivalently, suppose we do want to begin by considering observers of a given type, such as an observer falling towards a black hole. To compute probabilities, we must average over all causal patches that contain such an observer. In some patches the observer will be initially far from the boundary, in others he will hit the boundary very soon. This yields a probability distribution for the rate at which time ends

If we consider it in "many worlds" terms, then the wave function over the causal patch contains many different branches, and human observers (indeed our whole Milky Way galaxy) get to exist in lots of those branches. But in only a very few of the branches is our galaxy near the centre of the patch and able to continue to survive for 100s of billions of years; in most of the other branches we are somewhere off-centre, and will be smeared out against the horizon very much sooner. The fact that the Milky Way will continue to exist in some branches does not mean we should expect to survive in our branch. This reminds me somewhat of the discussions on quantum suicide.

Comment author: drnickbone 21 October 2012 04:40:17PM 0 points [-]

Thanks for this, though in a way, Susskind's interpretation seems to be even weirder than that of Bousso et al.

In Susskind's view, we would have to say that every galaxy apart from ours has an end-of-time experience, and gets smeared out on the horizon (or thermalized by de Sitter radiation), still in an average of about 5 billion years. But our own doesn't... so in 100 billion years or so we will be the lucky sole survivors in a universe containing a single remaining galaxy. Yet we are not really "lucky" because every other galaxy is experiencing the same thing from its own galacto-centric viewpoint. And while these individual amazing survivor stories are all consistent, there is no globally consistent story where all the galaxies continue to survive, just moving further and further apart. Strange...

Comment author: drnickbone 20 October 2012 11:17:44PM *  2 points [-]

Well horizons might not behave exactly the same (this is all theoretical physics) but there is quite a long chain of papers arguing that Hawking radiation arises from all sorts of causal horizons, and for the same sorts of reasons that motivate it for black hole horizons. See Gibbons-Hawking effect or look up "de Sitter radiation" on Google scholar. Here's just one paper.

With regard to your edit, the paper by Bousso et al does in fact discuss physical interpretations of the "end of time" effect, and scrambling into radiation appears to be the authors' preferred interpretation. See Section 5.3 on "causal patch measure" and this paragraph:

We now see that there is a different, more satisfying interpretation: the inside observer is thermalized at the horizon. This interpretation invokes a relatively conventional physical process to explain why the inside observer ceases to exist. Time does not stop, but rather, the observer is thermalized. His degrees of freedom are merged with those already existing at the boundary of the causal patch, the horizon.

Comment author: MugaSofer 21 October 2012 02:28:18PM 0 points [-]

Because they're both horizons, of course!

Comment author: abramdemski 13 November 2012 05:59:00PM 0 points [-]

I feel that it would be meaningful to claim that there are actually other universes which don't causally interact with ours, although (like the claim about photons disappearing when they are sufficiently far away from us) it would not be testable. This seems to be a counterexample to the causal connection requirement. [A good scientific theory would posit a common cause for these universes, but that is beside the point: it seems conceivable that they have no common cause.]

As such, I'm tempted to claim that what is real is just what actually is. There isn't an internal criteria for determining that, such as causal connectedness.

(This does not force any particular position about what is meaningful.)