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Hand vs. Fingers

25 Post author: Eliezer_Yudkowsky 30 March 2008 12:36AM

Followup toReductionism, Explaining vs. Explaining Away, Fake Reductionism

Back to our original topic:  Reductionism, which (in case you've forgotten) is part of a sequence on the Mind Projection Fallacy.  There can be emotional problems in accepting reductionism, if you think that things have to be fundamental to be fun.  But this position commits us to never taking joy in anything more complicated than a quark, and so I prefer to reject it.

To review, the reductionist thesis is that we use multi-level models for computational reasons, but physical reality has only a single level.  If this doesn't sound familiar, please reread "Reductionism".


Today I'd like to pose the following conundrum:  When you pick up a cup of water, is it your hand that picks it up?

Most people, of course, go with the naive popular answer:  "Yes."

Recently, however, scientists have made a stunning discovery:  It's not your hand that holds the cup, it's actually your fingers, thumb, and palm.

Yes, I know!  I was shocked too.  But it seems that after scientists measured the forces exerted on the cup by each of your fingers, your thumb, and your palm, they found there was no force left over—so the force exerted by your hand must be zero.

The theme here is that, if you can see how (not just know that) a higher level reduces to a lower one, they will not seem like separate things within your map; you will be able to see how silly it is to think that your fingers could be in one place, and your hand somewhere else; you will be able to see how silly it is to argue about whether it is your hand picks up the cup, or your fingers.

The operative word is "see", as in concrete visualization.  Imagining your hand causes you to imagine the fingers and thumb and palm; conversely, imagining fingers and thumb and palm causes you to identify a hand in the mental picture.  Thus the high level of your map and the low level of your map will be tightly bound together in your mind.

In reality, of course, the levels are bound together even tighter than that—bound together by the tightest possible binding: physical identity.  You can see this:  You can see that saying (1) "hand" or (2) "fingers and thumb and palm", does not refer to different things, but different points of view.

But suppose you lack the knowledge to so tightly bind together the levels of your map.  For example, you could have a "hand scanner" that showed a "hand" as a dot on a map (like an old-fashioned radar display), and similar scanners for fingers/thumbs/palms; then you would see a cluster of dots around the hand, but you would be able to imagine the hand-dot moving off from the others.  So, even though the physical reality of the hand (that is, the thing the dot corresponds to) was identical with / strictly composed of the physical realities of the fingers and thumb and palm, you would not be able to see this fact; even if someone told you, or you guessed from the correspondence of the dots, you would only know the fact of reduction, not see it.  You would still be able to imagine the hand dot moving around independently, even though, if the physical makeup of the sensors were held constant, it would be physically impossible for this to actually happen.

Or, at a still lower level of binding, people might just tell you "There's a hand over there, and some fingers over there"—in which case you would know little more than a Good-Old-Fashioned AI representing the situation using suggestively named LISP tokens.  There wouldn't be anything obviously contradictory about asserting:

|—Inside(Room,Hand)
|—~Inside(Room,Fingers)

because you would not possess the knowledge

|—Inside(x, Hand)—> Inside(x,Fingers)

None of this says that a hand can actually detach its existence from your fingers and crawl, ghostlike, across the room; it just says that a Good-Old-Fashioned AI with a propositional representation may not know any better.  The map is not the territory.

In particular, you shouldn't draw too many conclusions from how it seems conceptually possible, in the mind of some specific conceiver, to separate the hand from its constituent elements of fingers, thumb, and palm.  Conceptual possibility is not the same as logical possibility or physical possibility.

It is conceptually possible to you that 235757 is prime, because you don't know any better.  But it isn't logically possible that 235757 is prime; if you were logically omniscient, 235757 would be obviously composite (and you would know the factors).  That that's why we have the notion of impossible possible worlds, so that we can put probability distributions on propositions that may or may not be in fact logically impossible.

And you can imagine philosophers who criticize "eliminative fingerists" who contradict the direct facts of experience—we can feel our hand holding the cup, after all—by suggesting that "hands" don't really exist, in which case, obviously, the cup would fall down.  And philosophers who suggest "appendigital bridging laws" to explain how a particular configuration of fingers, evokes a hand into existence—with the note, of course, that while our world contains those particular appendigital bridging laws, the laws could have been conceivably different, and so are not in any sense necessary facts, etc.

All of these are cases of Mind Projection Fallacy, and what I call "naive philosophical realism"—the confusion of philosophical intuitions for direct, veridical information about reality.  Your inability to imagine something is just a computational fact about what your brain can or can't imagine.  Another brain might work differently.

 

Part of the sequence Reductionism

Next post: "Angry Atoms"

Previous post: "Awww, a Zebra"

Comments (94)

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Comment author: Jay2 30 March 2008 01:10:15AM 0 points [-]

This seems very Spinozist to me

Comment author: PK 30 March 2008 01:51:14AM 9 points [-]

If people can understand the concept of Unions from c/c++ they can understand reductionism. One can use different overlaping data structures to access the same physical locations in memory.

union mix_t { long l; struct { short hi; short lo; } s; char c[4]; } mix;

Unfortunately the blog ate my indentations.

Is mix made up of a long, shorts or chars? Silly questions. mix.l, mix.s and mix.c are accessing the same physical memory location.

This is reductionism in a nutshell, it's talking about the same physical thing using different data types. You can 'go up'(use big data types) or 'go down' use small data types but you are still referring to the same thing.

In conclusion, aspiring rationalists should learn some basic c++.

Comment author: ec429 14 September 2011 01:20:29PM *  8 points [-]

As a C programmer who hangs out in comp.lang.c, I'm strongly tempted to get out a copy of C99 so that I can tell you precisely where you're wrong there. But I'll content myself with pointing out that there is no guarantee that sizeof(long)==2*sizeof(short)==4*sizeof(char), and moreover that even if that did hold, there is still no guarantee that sizeof(struct {short hi; short lo;})==2*sizeof(short) because the struct might have padding - what if 'short' were a 16 bit quantity but stored in 32 bit words (perhaps because the arch can only do 32 bit writes, and has decided that short should be an int_fast16_t rather than an int_least16_t), resulting in alignment requirements?

In conclusion, PK should learn some basic C, and forget about the ++. (Old joke: what does C++ mean? Take C, add to it, then use the old version)

EDIT: thanks, paper-machine, and I approve of Markdown's choice of escape character. Now, if it'll just let me use \033[1;35m to change the colour...

Comment author: [deleted] 14 September 2011 01:25:19PM *  0 points [-]

Upvoted for delicious, delicious C.

EDIT: However, you may want to work on the markdown; * is a reserved character ;_;

Comment author: thomblake 14 September 2011 02:07:20PM 3 points [-]

I don't see anything wrong with grandparent, assuming a particular architecture. And whenever I used to write c, it was almost always for a particular architecture, usually with inlined assembly. Am I missing something, or are you just trying to make some point about portability regarding a metaphor?

Comment author: ec429 14 September 2011 04:41:55PM *  4 points [-]

It is a lesson hard-learned over many programmer-years of coding that portability should be acquired as an innate reflex; that whenever you are about to sacrifice portability, you ask yourself "Why am I doing so, are there alternatives, and have I done at least a rudimentary cost/benefit analysis of this decision?"

What you don't do is throw away portability just because you happen to be using a particular machine right now. This is something quickly learned in comp.lang.c.

Incidentally, a better model than PK's might be:

typedef struct foo {int i} s;

s f;

Now what is 'f'? Is it an 's', is it a struct foo, or is it an int? And what about f.i? Both have the same address, casting either's address to any of the pointer types 's *', 'struct foo *' or 'int *' is valid; writing

*(int *)&f=1;

does just the same as f.i=1; quite possibly the compiler will generate the same code, because after all, the territory is the same. It's just that "f.i=1" is a higher-level map, which conveniently abstracts things out.

This is made more explicit by considering struct bar {int a; long b;} t; *(long *)(((char *)&bar)+offsetof(bar, b))=1; // same as bar.b=1

Of course, you could go to all the trouble of computing the offset pointer every time, since that's what happens on the "quark" (assembly language) level of the territory, but the higher-level 'struct' map is cognitively useful.

Comment author: Dan3 30 March 2008 03:53:35AM 2 points [-]

"Eliminative fingerists" is amusing. I think that particular projection fallacy as pertains to minds is part of a larger tradition, however. Radical behaviorists, for instance, really ought to be included. They feel left out, off on their lonesome, busily declaring that the "mind" is a convenient fiction because it can't be measured.

... and seperately, I might note that I've read through much of your archives and enjoyed it immensely. Keep it up!

Comment author: Phil_Goetz2 30 March 2008 04:08:45AM 6 points [-]

I'm confused as to what your purpose is with this series on reductionism. Is there a particular anti-reductionist position you're combating?

Earlier, you wrote,

Reductionism is not a positive belief, but rather, a disbelief that the higher levels of simplified multilevel models are out there in the territory.

I don't think your typical anti-reductionist is concerned about the existence of different levels of models. I've never heard one ask "How can you model the plane without the wings?"

Anti-reductionists are opposed to models in general. An anti-reductionist believes that a collection of things has properties that are not the results of the combined properties of the things in the collection, let alone of a model. For example, they would say that a human has free will, even though the constituents of the human are deterministic; or that a human has a soul, but if you constructed a human from parts, it wouldn't; or that representations in a human brain have meaning, while representations in a computer cannot; or that a human brain has consciousness, etc.

So I don't think what you're writing addresses what it is that reductionists believe, that non-reductionists don't believe.

Anti-reductionism equals spiritualism, and it is not the opposite of materialism, but of science. Science is not materialistic, since we believe in fields. Also, if you discovered that spirits were composed of magnetic fields, and conducted experiments on them, you would still be a scientist. The spiritualist, by contrast, uses the term "spirit" to name something that can't be explained. Anti-reductionism = spiritualism = the belief that there exist complex phenomena ("spirits") with no explanations.

Comment author: Phil_Goetz2 30 March 2008 04:16:49AM 3 points [-]

If you want to fight the good fight, edit the section "Limits of Reductionism" in the Wikipedia article on Reductionism. It cites many examples of things that are merely complex, as evidence that reductionism is false.

Comment author: poke 30 March 2008 04:36:29AM 3 points [-]

I can't tell from your parody of positions in the philosophy of mind whether you're criticizing eliminative materialists or critics of eliminative materialism.

Comment author: Richard4 30 March 2008 05:16:36AM 0 points [-]

Eliezer - "Your inability to imagine something is just a computational fact about what your brain can or can't imagine."

Who ever suggested otherwise? Again, see the 'epistemology' section of my 'Arguing with Eliezer: Part I'. What I take as evidence is not "I have an intuition that P", but simply P itself. You might undermine my argument from P to Q by showing some flaw in the thought process that led me to the premise P, but I don't see that you've done this yet (as opposed to merely explaining why you might expect me to have such a belief). Merely pointing out that thoughts occur in my head certainly isn't telling me anything I didn't already know!

"And you can imagine philosophers who criticize 'eliminative fingerists'..."

Of course, it's logically impossible to have the fingers and all without a hand. All that we mean by 'hand' is the collection of fingers + palm, etc. There's no sense to be made of the idea of the finger world which lacks the appropriate bridging laws to give rise to hands. Merely understanding the terms suffices to make this clear.

On the other hand, (we have every reason to believe that) it's logically possible to have neurons fire without this being accompanied by any phenomenal consciousness. We certainly don't just mean a certain kind of physical or behavioural/functional role by our term 'consciousness'. And we can easily make sense of how the world would be different if it lacked the natural laws that give rise to consciousness. Conceptually competent philosophers can understand the so-called "zombie world" just fine.

So there's simply no analogy here. Needless to say, the mere fact that you can "imagine" stupid philosophers is not any sort of counterargument to the actual philosophers you pretend to respond to. I mean, I can imagine a world where you actually engage with opposing arguments rather than merely mocking them; alas, my imagining does not make it so...

Comment author: Unknown 30 March 2008 06:43:39AM 0 points [-]

For one thing, Eliezer misunderstands the meaning of "eliminative." An eliminative materialist is someone (by their own definition) who holds that certain things do not exist, say for example beliefs or choices. Eliezer believes that these things are material things, but at least he believes that they exist, as he said about the rainbow. An eliminative materialist says that the word "belief" and "choice" refer to something that does not exist in reality at all, not that they refer to something material. Of course this position implies its own non-existence, since the word "position", taken in this way, would also refer to something that doesn't exist in reality.

As regards the substantial disagreement between Richard and Eliezer, Richard is so obviously right, and Eliezer so obviously wrong, that I am simply speechless.

Comment author: Eliezer_Yudkowsky 30 March 2008 06:52:56AM 4 points [-]

Poke: Criticizing the critics.

Richard: What exactly is the 'P' that you think you're taking as a premise, here?

Also, in "Arguing with Eliezer", you write:

I find this commitment less absurd than denying the manifest reality of first-personal conscious experience (as reductive materialists like Dennett and Eliezer do), or engaging in the metaphysical contortions that non-reductive materialists must (see my 'dualist explanations' post).

If, as you claim, you understood my argument fully and rejected it due to arguments I fail to understand, then why are you writing what I must object to as a major misrepresentation of my views as I see them?

Namely: From my viewpoint, I'm certainly not denying your first-person conscious experience - just saying that it doesn't work the way you think it does.

Comment author: Eliezer_Yudkowsky 30 March 2008 07:10:15AM 15 points [-]

Richard, also, from your "Dualist Explanations":

Once the brain matter is there, they think that's all there is to consciousness -- there's nothing further to explain. Most of us think there is something still to be explained, and dualism can achieve this by positing bridging laws that cause 'mind' to emerge from 'matter'.

Looks like a clear-cut case of Mind Projection Fallacy to me, or, at the very least, a severe misrepresentation of how a mature reductive materialist sees their own viewpoint. A reductive materialist need not pass from "Brain dynamics entirely and strictly constitute consciousness" to "There's nothing further to explain." There is plenty more to explain, namely, the nature of the identity.

Knowing that != knowing why != knowing how != seeing how.

If you merely know that mind=brain you may have a great deal left to explain. You may still need to find the insights needed to dissolve the apparent impossibility of mind=brain.

The map is not the territory, so you can't jump from

mind=brain

to

(mind=brain)->know('mind=brain')

to

know('mind=brain')->know_how('mind'='brain')

to

~know_how('mind'='brain')->~(mind=brain)

You seem to jump from "The identity 'mind=brain' seems unsatisfying" to "I have just cause to believe that mind is not matter". Of course the mere asserted identity seems unsatisfying: If you don't know any of the actual reductions, the mere materialist assertion that some reduction exists won't let you make any new predictions. This does not give you just cause to reject materialism; it gives you just cause to believe that your map is missing some reductions.

Postulating "bridging laws" completely fails to explain the lingering mysteries in any fashion whatsoever. It makes no new predictions even in retrospect; it is anticipation-isomorphic to "magic" or "God did it" or "elan vital" or "some reduction exists, but I won't tell you what". Note that if you actually accepted "The mind equals the brain!" as an answer to consciousness, it would also constitute a mysterious answer to a mysterious question: believing it would not make you any less confused. The answer is when consciousness stops being mysterious - this requires an actual reduction, not just a flat assertion that a reduction exists.

Which, of course, it does.

Comment author: Unknown 30 March 2008 07:32:18AM 0 points [-]

Eliezer: that last response makes some progress, since this is the first time I have seen you concede that "why is mind the same as the brain in a certain condition?" is a sensible question that needs an answer.

Given this, what makes you think it is possible to answer the question at all? Just because a question makes sense doesn't mean we can give an answer to it. And just because all the questions that you have answered in the past had answers, doesn't mean the the ones you haven't answered have answers. It couldn't have been otherwise: of course your answered questions had answers. This says nothing about the remaining ones.

And complaining that postulating "bridging laws" is isomorphic to saying "God did it" does not help. Postulating that energy is conserved is isomorphic to the same thing. Bridging laws or purely physical laws are necessarily both and equally postulates.

Comment author: Dan3 30 March 2008 12:04:49PM 1 point [-]

I can't presume to answer for Eliezer, but I don't think he's yet claimed to know how the brain works. He's also paid considerable attention to the nonsensical nature of some attempts to say that we might "already" know how- IE "emergence", "complexity", and other non-explanations. I'd go so far as to say that it follows directly from the fact that we can't make our own brains from first principles that we don't really understand the ones currently in circulation.

That said, it would be a serious defiance of all precedent if brains somehow had a magical, non-reducible quality by which they refused to comply with empirical observation. It's true that the past success of such study can't reliably predict future trends. By the same logic, however, we can't expect gravity to continue in the future because past trends and consistency are of a different substance than future ones. Until gravity and reductionism actually do give out, we can say reasonably well that gravity is likely to continue and things are likely to be explicable. Following this line of reasoning - that the past may not predict the future at all - could easily kill any plotted course of action relying upon gravity or causality equally well, so why apply it only to cognitive science?

As pertains to brains, we have reasonable inferences that the mind is strictly anchored in a physical substance. Among the oldest I'm aware of is Heraclitis' observation that hitting someone in the head causes stupor, confusion, etc, so the mind probably resides there. More modern versions can include research into brain lesions, neurotransmitters, psychoactive drugs, and the like if you prefer. The only way I can imagine to actually rule out a purely "physical" brain, especially against the weight of current evidence, would be if we could finally map the brain to perfection, watch all the computation it's carrying out, understand it all- and still demonstrate that there's a mysterious magic term in the input or output that definitely comes from nowhere at all. It sounds ridiculous spelled out this way, but that's essentially what postulating "non-reducibility" comes down to- that monitoring an entire brain physically, you could actually watch things come out of nowhere. Certain physicists would find this kind of disturbing, for one.

Additionally, "God did it" and "Energy is conserved" are not isomorphic. One explains nothing; it does not provide any way to plot future events, assuming causality and a fairly stable universe. The other one does provide a way to plot future events, assuming causality and a fairly stable universe. Again, if you want to chuck out causality and a fairly stable universe, I have to wonder why you bother finishing sentences seeing as sound and information propagation are bound to stop working at any time. If we can agree that causality and stability are to remain in play, however, it follows that certain models will correspond to predictable reality and others will not. Going against this doesn't just undermine AI or cognitive science, it actually undermines empiricism in general, which is funny because empiricism has a pretty good track record in spite of it.

Comment author: michael_vassar3 30 March 2008 01:33:05PM 1 point [-]

I'm not convinced that we can have real probability distributions over impossible possible worlds. At the very least, a real probability distribution must sum its exhaustive and exclusive possibilities to 1, but in fact it seems to me that the same type of effort that is needed to show that a set of impossible possibilities sums to 1 also changes the degree to which they have been examined, changing their subjective probabilities. It specifically seems to me that pseudo-probability distribution over impossible possible worlds will generally contain non-correctable biases from framing such as overconfidently narrow probability distributions, or conversely conjunction fallacies and subadditivity. For a concrete example, after estimating the probability that an albino tiger which has previously performed on the Daily Show is sneaking up behind me as I write this in order to deliver a pizza, the probability that I am left with will be sufficiently low that it will be utterly dominated by skeptical hypotheses about either my calculation (even after checking 10 times I may have misplaced a decimal point. I may even be deluding myself about my knowing how to multiply or about the validity of 'multiplication') or my world (which may actually be a short 'joke sim' of an agent existing only to make some extremely low estimate of some event's probability and then be proven wrong). These are specifically the sorts of scenarios in which conjunction fallacies are not actually fallacies, and also where non-additivity is valid, framing effects are valid, etc, as given the skeptical nature of the scenario simply the formation of the frame constitutes evidence. To call this sort of uncertainty, which cannot be mathematically manipulated and processed a "probability distribution" ignores the fact that "Probability distribution" is a mathematical concept with specific properties.

Comment author: Matthew_C.2 30 March 2008 01:39:01PM 0 points [-]

As pertains to brains, we have reasonable inferences that the mind is strictly anchored in a physical substance. Among the oldest I'm aware of is Heraclitis' observation that hitting someone in the head causes stupor, confusion, etc, so the mind probably resides there.

Yes and when I hit my radio with a rock it might stop working, change the station, if I rip out transistors it might make the sound distorted, etc. That really doesn't prove that the song is stored inside the radio, does it?

If you are interested in reality instead of just fitting in with current intellectual fashion, you really need to step outside the echo chamber sometime and engage with the best arguments against your current positions, not simply flail against strawmen.

And a special point for commentor Richard above -- you have an interesting and mostly thoughtful blog and you do a good job pointing out some reasons why eliminative materialism is a problematic belief. But then you stumble badly by claiming that only the only sane non-reductionist position is that mind arises from the brain. Claiming that people with different ideas than you must be insane is a position that has often been expressed in the history of intellectual discussion, but almost never by those on the correct side of a debate. . .

Anyway, I won't debate this point here any further because this blog is not interested in examining its philosophical biases towards materialism. I only wanted to point out an interesting reference book to those readers here not already utterly convinced that their beliefs are correct and their opponents not sane -- I know there are lurkers here that fit that description. . .

Comment author: Ian_Maxwell 30 March 2008 01:48:09PM 0 points [-]

I agree with some others that Eliezer is here arguing against a fairly na誰ve form of anti-reductionism, and indeed is explaining rather than refuting it. However, I assume, Eliezer, that the point of your entry is (in keeping with the theme of the blog) to illustrate a certain sort of bias through its effects, rather than to prove to everyone that reductionism is really truly true. So explanation over refutation is entirely appropriate here.

Comment author: Unknown 30 March 2008 01:52:44PM 0 points [-]

Dan: "Every question I've so far been able to answer, had an answer," is logically necessary. Thus it provides no evidence, not even probable evidence, for any empirical conclusion, such as "every question has an answer." If Eliezer had answered every question he has ever been asked, this would be probable evidence that he would be able to answer future questions. Since this is not the case, he has presented exactly zero evidence that all questions can be answered.

We weren't discussing the question of whether there is some magical input or output from the brain. As Matthew C. correctly points out, we all assumed (and I assume as well) that there is no magical output. The question is "why is the brain conscious," and this question is not answered no matter how many times you may say that consciousness is identical with the physical activity of the brain.

A bridging law such as Richard is proposing would be something like "when a physical system, i.e. like the brain, is in condition XYZ (a physical description), then it will be conscious of redness, and when it is not in condition XYZ, it will not be conscious of redness." This bridging law allows one to predict the future: it allows one to predict when one will see redness and when one will not. It predicts the future just as well as the law of conservation of energy. Either both are isomorphic with "God did it," or neither are. Eliezer simply meant to say that the bridging law still doesn't explain WHY the brain sees redness. And the law of conservation of energy doesn't explain WHY energy is conserved, it just asserts it.

Comment author: bigjeff5 02 February 2011 12:28:11AM *  -1 points [-]

A bridging law such as Richard is proposing would be something like "when a physical system, i.e. like the brain, is in condition XYZ (a physical description), then it will be conscious of redness, and when it is not in condition XYZ, it will not be conscious of redness."

I'm sorry, maybe I'm just not getting it, but such laws seem utterly obvious and completely unnecessary when taken from the position that the mind is determined entirely by physical processes (i.e. atoms, molecules, etc).

By way of analogy, I'll use a computer display. What is seen on a computer display is a culmination of trillions of transistors being in a certain state at a certain time. I may see a picture of a dog on the display, but if I look real close I can see thousands of red, green, and blue lights which make up a pixel. Each pixel has a specific description for the level of light for each sub-pixel needed to create the proper color for that particular portion of the image. This description is held in a specific pattern of positively or negatively magnetized iron molecules. This pattern is used to "switch" certain transistors one way and other transistors the opposite way, creating a specific electrical path through the silicon - like a train lever switches the path a train is on - which culminates in the specific color combination of the pixel in question. This pattern for this pixel is part of a similar, larger pattern which includes thousands of such patterns. The result is a dog on the screen, created by a thousand very specific paths of electricity repeated 60 times per second.

Even in that description, I skipped over a lot of what happens, but you should get the gist. Put a computer scientist and an electrical engineer in the same room and they can explain in perfect detail how everything you see on a computer screen physically happens. I don't see how consciousness in relation to the brain is any different from the computer monitor in relation to the computer hardware in my analogy above. The only reason someone might think the picture of the dog is not determined by a specific path of electrons is because they do not understand how a computer works.

Comment author: Ian_C. 30 March 2008 02:04:21PM 0 points [-]

"To review, the reductionist thesis is that we use multi-level models for computational reasons, but physical reality has only a single level."

But wouldn't an ultimate/complete physical model of reality have to explain why our brains, when hit with certain stimuli, produce a world of solid coloured objects? (To disagree would be to admit the content of our minds is mystical and other worldly.) And if the model does explain it, then aren't our maps part of reality too (i.e. real)? So therefore isn't reality multi-level?

Comment author: Perplexed 01 August 2010 08:24:49PM *  2 points [-]

I don't see how you get to multi-level reality by this thinking. But part of the problem of speculating about the philosophical consequences of reducing mind to brain is that we don't have a complete actual reduction to point to.

There is only one example I know of where a map of the territory has been perfectly embedded within the territory; where the map elements really correspond to territory elements; where every territory element is represented by a map element; and where some particular territory elements correspond to (are the physical substrate for) map elements. That example is the proof of Godel's incompleteness theorem for arithmetic.

The details of the mappings in each direction between map and territory are complicated, but mundane. However, the consequences of this embedding are at least a little bit interesting in this context. Godel finds that the embedding must be disappointing to an Eliezer-like reductionist. I don't think that you can twist his result into support for a multi-level reality (or multi-level territory). But he does show that the territory is rich enough so that no single map can completely cover it; that you may need infinitely many levels of map to completely cover everything that is out there in the territory.

Now Godel's theorem is just an analogy here. There is no particular reason why difficulties in finding a compact and satisfactory first-order logical foundation for mathematics necessarily tell us anything useful about difficulties in finding a foundation for physical reality. But still, since we all admit that we don't really know how deep the true territory lies below our best modern maps, and since the history of physics is that the maps keep getting improved with no end in sight, shouldn't we at least remain open to the possibility that the territory is non-existent (or at least inaccessible) and that all of science is just a series of better and better maps? If it is "maps all the way down" and if our current best map is not the territory, doesn't that kind of turn around our intuitions as to who is committing the Mind Projection Fallacy here? Is it Mind Projection to imagine that the territory actually exists simply because you have a map of the places you are interested in? Or is it Mind Projection to deny that a map exists simply because you don't have a map for your area of interest?

Comment author: bigjeff5 02 February 2011 12:56:28AM 0 points [-]

I'm no mathematician, but Godel's theorems seem to have some heavy constraints placed on them. I also don't see how this maps territory to the map, it still seems like a map of the territory. More like saying "under certain conditions, it's impossible to draw a better map."

I think an important thing to realize is that the map is never the territory. It is merely a description of the territory. Some maps more accurately portray the territory than others, but it doesn't make them any closer to actually being the territory. Even a map that perfectly describes the territory in every possible detail is still just a map, it is not the territory itself. The map is the map, the territory is the territory, the map describes the territory. There can be as many maps as you need, covering as much detail as you need for your given application, but there is still only ever one territory.

The same way, there is a concrete reason that mathematics works the way it does, else it wouldn't work the way it does, and since there is such a reason we should be able to find it. Godel's theorems are no reason to stop looking, though they may be a reason to look somewhere else.

Comment author: RobinHanson 30 March 2008 02:19:25PM 2 points [-]

Richard, I'm always amazed at what philosophers think they can see merely by "understanding the terms." Such analysis may well tell us a lot about what we often assume, but I am skeptical that it can tell us as much as philosophers think about what is actually possible vs. only apparently possible.

Comment author: Caledonian2 30 March 2008 02:23:00PM 1 point [-]

I would love to see Eliezer defend his claim that the physical world has only one level. Precisely how does he know that? We cannot confirm that our various models of phenomena can be reduced to the most basic physics.

Comment author: Dan3 30 March 2008 02:32:41PM 2 points [-]

Yes and when I hit my radio with a rock it might stop working, change the station, if I rip out transistors it might make the sound distorted, etc. That really doesn't prove that the song is stored inside the radio, does it?

Well, no. All else being equal, however, and absent evidence for radio waves, the most parsimonious explanation IS that the song is stored in the radio. Absent evidence of immaterial souls, the same applies to brains. Heraclitis could fairly easily have been wrong, since he was just going on the effects of gross trauma. Fortunately, we have advanced some since Heraclitis, having discovered the neuron, brain areas responsible for different tasks, computing in general, fMRI scans, and other fun stuff. This has gone a certain way towards confirming his hypothesis. I'm not saying it's impossible that there's a soul floating around communing with the brain. Fully material, reducible brains are not, in my estimation, as certain as gravity could be said to be- but the brain is not exactly growing more mysterious and inexplicable as our study goes on, and betting on the side of inexplicability has not had a good record these past few hundred years.

Also, I'm sorry that you didn't want to actually present a reason that I'm wrong, as opposed to asserting that I'm biased, following trends, not worth arguing with, etc. My "bias towards materialism" is only that it's usually proven right in the past and in my experience. I'm afraid that I'm going to have to put off reading any more parapsychology than I've done in the past on the basis that there's probably nothing new in it.

A bridging law such as Richard is proposing would be something like "when a physical system, i.e. like the brain, is in condition XYZ (a physical description), then it will be conscious of redness, and when it is not in condition XYZ, it will not be conscious of redness." This bridging law allows one to predict the future: it allows one to predict when one will see redness and when one will not. It predicts the future just as well as the law of conservation of energy. Either both are isomorphic with "God did it," or neither are. Eliezer simply meant to say that the bridging law still doesn't explain WHY the brain sees redness. And the law of conservation of energy doesn't explain WHY energy is conserved, it just asserts it.

No, I don't think that's what he means. A "bridging law" is the same as an "emergent property" or a "complex system"- specifically, it asserts that a reduction and explanation exists, and it sounds like it provides one, but it does not actually do so. This makes it fundamentally useless. Conservation of energy states the difference between prior and posterior amounts of energy should be 0. This is a precise prediction. If it were isomorphic to the "bridging law", it would state that there is some transformation that describes the relations between prior and posterior states of energy in a system- which is to say, that they make sense "somehow". It's a functionally meaningless statement, and it doesn't tell you anything about what it's describing any more than asserting an suggest "appendigital bridging law" would tell us about hands.

As for questions having answers, I've already gone on about the empirical validity of a few observations unto preaching. Suggesting that an empirical question, such as how a brain works, might be unanswerable because of the fundamental philosophical unanswerability of questions in general is sophistry at best. The ability to ask and answer questions to some approximation is so fundamental that you can't even assert gravity without it. Trying to undermine this is silly.

Comment author: PK 30 March 2008 02:59:34PM 1 point [-]

Everyone ignored my c++ example. Was I completely off base? If so please tell me. IMHO we should look for technical examples to understand concepts like "reductionism". Otherwise we end up wasting time arguing about definitions and whatnot.

Personally, I find it irritating when a discussion starts with fuzzy terms and people proceed to add complexity making things fuzzier and fuzzier. In the end, you end up with confused philosophers and no practical knowledge whatsoever. This is why I like math or computer science examples. It connects what you are talking about to something real.

Comment author: bigjeff5 02 February 2011 01:03:04AM 0 points [-]

I think it works pretty well if you've coded before.

I also think that's why Eliezer likes to use pseudo-code in his explanations.

Comment author: Patrick2 30 March 2008 03:47:16PM 0 points [-]

Michael:

I'm not convinced that we can have real probability distributions over impossible possible worlds. At the very least, a real probability distribution must sum its exhaustive and exclusive possibilities to 1, but in fact it seems to me that the same type of effort that is needed to show that a set of impossible possibilities sums to 1 also changes the degree to which they have been examined, changing their subjective probabilities. It specifically seems to me that pseudo-probability distribution over impossible possible worlds will generally contain non-correctable biases from framing such as overconfidently narrow probability distributions, or conversely conjunction fallacies and subadditivity.

Well, for a simpler example (with only finitely many cases), it can look a bit better. For example, take the Riemann Hypothesis— please. Mathematicians have informally been saying for years that based on the exact precision of the first trillion cases and on the rich consequences derived from it, that they think it's almost certainly true, pending a proof.

Clearly, two of the three universes "The RH can be proved", "The RH can be disproved", "The RH is undecidable from ZFC" are logically impossible; we just don't know which. Still, it doesn't seem illegitimate to portion probability between these three cases.

This isn't strictly Bayes, it seems, because the theoretical Bayesian reasoner contains all logical consequences; but I don't think it's thereby an invalid process to arrive at subjective probabilities.

Comment author: Frank_Hirsch 30 March 2008 04:17:15PM 1 point [-]

PK: I don't see the ++ in your nice example, it's perfectly valid C... =)

Caledonian, Ian C.: I know of no models of reality that have superior explanatory power than the standard reductionist one-level-to-bind-them-all position (apologies for the pun). So why add more? In a certain way "our maps [are] part of reality too", but not in any fundamental sense. To simulate a microchip doing a FFT, it's quite sufficient to simulate the physical processes in it's logic gates. You need not even know what the chip is actually supposed to do. You just need a very precise description of the chip. If you do know what it's doing, it's of course much more efficient to directly use the same algorithm it is also using. That will also dramatically cut down on the length of it's description. But that does not make the FFT algorithm fundamental in any way. It is just a way to look at what is happening. I mean, really, this shouldn't be so hard to grasp...

Comment author: Caledonian2 30 March 2008 04:23:34PM 1 point [-]

I know of no models of reality that have superior explanatory power than the standard reductionist one-level-to-bind-them-all position (apologies for the pun).

Sure you do. That's why we have biology and chemistry and neuroscience instead of having only one field: physics.

Since we don't currently know whether our models of the most basic known components of the physical world are compatible with our high-level models of phenomena, they are ALL better within their limited domain than more general models are.

This is not a problem for anyone wanting merely to produce a useful model. It is a profound problem for anyone wanting to produce a ur-model that encompasses all known phenomena.

Comment author: bigjeff5 02 February 2011 01:17:36AM *  1 point [-]

Sure you do. That's why we have biology and chemistry and neuroscience instead of having only one field: physics.

Are not these models simply abstractions of physics? That is, simply higher levels of the same systems that physics describes? We know chemistry conforms to physics, and we know biology conforms to chemistry, does biology somehow not conform to physics?

Since we don't currently know whether our models of the most basic known components of the physical world are compatible with our high-level models of phenomena, they are ALL better within their limited domain than more general models are.

Do we not know this? I thought we did.

The high level models are certainly more practical for their given applications than attempting to work the whole thing out from the movement of quarks, but they are certainly not more accurate. It's the difference between using a globe to find Australia (high level map), and a world atlas to find a road in Sydney (lower level map). It's a lot easier to find Australia on a globe than it is in an atlas, but that does not mean you cannot use the atlas to do so, and it certainly doesn't make the globe more accurate than the atlas, for you'll never find that particular road on a globe. Better for the task, perhaps, but only because you do not need the level of detail the lower level map provides.

Comment author: Richard4 30 March 2008 04:23:51PM 0 points [-]

Robin - 'I'm always amazed at what philosophers think they can see merely by "understanding the terms." Such analysis may well tell us a lot about what we often assume, but I am skeptical that it can tell us as much as philosophers think about what is actually possible vs. only apparently possible.'

What kind of possibility are you talking about? Philosophers will grant that reason/understanding alone can't tell us what's physically possible. That's the domain of science. But logical possibility is simply defined as what can be coherently understood, i.e. without implicit self-contradiction, so I'm not sure how your objection could possibly work here. Unless, perhaps, you meant to express skepticism that philosophers really understand the terms they claim to understand? (If it turns out that all our claims are really based on misunderstandings, then they wouldn't even establish logical possibility. But that's precisely because we -- like Eliezer's imagined nutcase philosopher who doesn't understand that hands are logically reducible to fingers etc. -- would be lacking the prerequisite understanding to justify our conclusions.)

Dan - I don't know what "emergent property" or "complex system" are supposed to mean, but Unknown got "bridging law" just right. Granted, it's one thing to assert there's a bridging law, and another to actually provide one. Eliezer grants the same point with regards to reductions. The difference between our views is that he thinks the reduction is logically necessary; that there is no sense to be made of the idea of a 'zombie' world physically identical to ours but lacking consciousness. I think that's plainly false. There's nothing incoherent about the idea of zombies. So the admitted link between the physical and phenomenal facts is merely contingent (taking the form of a natural law, rather than a reductive analysis).

P.S. You've been reading too many straw men. I certainly don't think "there's a soul floating around communing with the brain". Follow the links in my earlier comment.

Comment author: Frank_Hirsch 30 March 2008 04:49:18PM 1 point [-]

Caledonian: Sure you do. That's why we have biology and chemistry and neuroscience instead of having only one field: physics.

That's just a matter of efficiency (as I have tried to illuminate). There is nothing about those high level descriptions that is not compatible with physics. They are often more convenient and practical, but they do not add one iota of explanatory power.

Comment author: Caledonian2 30 March 2008 05:09:33PM 0 points [-]

There is nothing about those high level descriptions that is not compatible with physics.

Since we can't extrapolate our physics that far, we don't know whether they're truly compatible with our understanding of physics or not.

The difference between our views is that he thinks the reduction is logically necessary; that there is no sense to be made of the idea of a 'zombie' world physically identical to ours but lacking consciousness. I think that's plainly false. There's nothing incoherent about the idea of zombies.

Of course there is. If a feature can be removed from a model without affecting any outcome of the model, that feature never applied to the system we're trying to model. It didn't exist.

If you postulate a world that functions precisely as ours does in every way, but a mysterious property called 'consciousness' has been removed, than 'consciousness' does not and cannot exist in our world. It affects nothing. It is affected by nothing. It is not a part of existence.

Saying that something has absolutely no consequences of any kind, while asserting that it exists, is incoherent. The p-zombie concept is incoherent.

Comment author: Chris3 30 March 2008 05:12:31PM -2 points [-]

"Recently, however, scientists have made a stunning discovery: It's not your hand that holds the cup, it's actually your fingers, thumb, and palm."

What, are we in third grade? Are you really dedicating a whole post to the semantics of composition? Is it really that hard to fathom that the hand is composed of the fingers, thumb, and palm?

This just in! Scientists recently discovered that it's not actually people that post pretentious blog articles, but instead a sophisticated arraignment of meat popsicles.

Comment author: Frank_Hirsch 30 March 2008 05:30:44PM 0 points [-]

Caledonian: "Since we can't extrapolate our physics that far, we don't know whether they're truly compatible with our understanding of physics or not." For the sake for argument, I'll let that stand (as a conflict of minor importance). Still, why should we go and assume a non-reductionist model? That's multiplying entities beyond necessity.

Comment author: Richard4 30 March 2008 06:00:54PM 0 points [-]

Caledonian - the addition of p-consciousness has no physical consequences. To infer that it has "absolutely no consequences of any kind" is obviously question-begging against those of us who hold that there are non-physical facts (e.g. what it is like, subjectively, to be in such-and-such a physical state). The zombie world is appreciably different from ours in these other respects.

Incidentally, the principle you depend upon is self-defeating. Consider:

(Scientism): A claim is coherent only if it has scientific implications.

What are the scientific implications of this principle? What empirical test would show whether Scientism is true or false? It is incoherent by its own lights.

Comment author: Frank_Hirsch 30 March 2008 06:15:32PM 0 points [-]

Richard: Yes, there is a reality beyond reality! Sure, it's not real in the sense that it is measurable or measurably interacts with our drab scientific reductionist reality, but it's... real! Really! I can feel it! So speak the Searle-addled...

Comment author: poke 30 March 2008 06:19:04PM 0 points [-]

Caledonian,

Modern chemistry is an extension of physics. The theories that chemists use were literally extrapolated from the physics; they're physically accurate extensions of the physical behavior of the hydrogen atom. (They cut corners but we know how to cut corners; physics is all about simplification.) Modern biology is built on biochemistry (which is just the chemistry of large organic molecules). Neurobiology is biology (and biochemistry and biophysics). Mineralogy is built on chemistry and founds modern geology (along with physics). Astrophysics is obviously physics; cosmology is physics; and so on. Most of the dividing lines are obviously institutional. Which part of all this, exactly, would you object to?

Comment author: Unknown 30 March 2008 06:30:19PM 0 points [-]

Has anyone yet stopped to consider the fact that we came up with physics in order to predict what we would see, hear, and feel next?

If claims about seeing, hearing, and feeling, are literally statements about brains and atoms, why did we have to come up with physics at all? We should have already known what we were talking about.

Comment author: Eliezer_Yudkowsky 30 March 2008 06:30:28PM 1 point [-]

Sez Richard:

The difference between our views is that he thinks the reduction is logically necessary; that there is no sense to be made of the idea of a 'zombie' world physically identical to ours but lacking consciousness. I think that's plainly false. There's nothing incoherent about the idea of zombies. So the admitted link between the physical and phenomenal facts is merely contingent (taking the form of a natural law, rather than a reductive analysis).

"Plainly false?" You mean you can imagine a world identical to ours but lacking 'consciousness', therefore, it is logically possible? But logical possibility does not follow from conceptual possibility. You may simply have not yet proved the tautology

|- Inside(x, Hand) -> Inside(x, Fingers)

which you would need to see that your conceptual imagining is logically impossible.

I don't know whether 577 is prime, so it is conceptually possible to me that it is prime or composite, but only one of these two alternatives is logically possible. I can conceive that 577 is prime, or alternatively, that it is not prime, and yet 577+2 = 579 either way; but this does not imply that the primeness of 577 is a detachable property that floats around independently of its arithmetical behavior. It just means I don't know.

This is the fundamental Mind Projection Fallacy I think you are committing in passing from "I can imagine zombies" to "Zombies are logically possible" to "The 'bridging laws' that imply consciousness are contingent physical facts rather than logical implications."

Indeed, the whole notion of a "bridging law" consists of committing the Mind Projection Fallacy with respect to theorems like

|- Inside(x, Brain) -> Inside(x, Mind)

and supposing that they describe physical causation, something that happens out there in the world, rather than knowledge deductions. The rule that states that a hand is present when fingers+palm+thumb are present, is not a physical cause, or a contingent bridging law, but a consequence of the definitions of the discovered referents of "hand" and "fingers+palm+thumb". You don't know the definition of the undiscovered referent of "consciousness" so you can't see the logical identity, but it is there - this is what a reductionist believes.

Unknown, Dan has described very well the difference between "A bridging law did it!" and Conservation of Energy.

Comment author: Unknown 30 March 2008 06:33:48PM 0 points [-]

Eliezer, Dan did not describe the difference between bridging laws and the conservation of energy. Read Richard's statement about what he meant by a bridging law.

Comment author: poke 30 March 2008 06:39:16PM 0 points [-]

Richard,

I think your refutation of "scientism" is somewhat disingenuous and suffers from what I like to call the "everything is philosophy fallacy." When a scientist says "philosophy is nonsense" they have obvious scientific grounds: philosophical reasoning isn't a part of the scientific world view. There's no difference between saying "philosophy is nonsense" and saying "religion is nonsense." Criticizing them on the grounds that this isn't good philosophy is ridiculous. One doesn't need to philosophize to communicate.

Comment author: Caledonian2 30 March 2008 06:53:29PM 2 points [-]

the addition of p-consciousness has no physical consequences. To infer that it has "absolutely no consequences of any kind" is obviously question-begging

Talking is a physical act. Remembering is a physical act. Thinking is a physical act. If your 'p-consciousness' has no physical consequences, it cannot affect the way people think and remember and talk. None of the philosophers who think and remember and talk about their supposed non-experiential experiences can be causally connected to the thing they're supposedly experiencing.

Again: your position is incoherent. Your conception of 'non-physical facts' is meaningless and without semantic content.

Comment author: Tiiba3 30 March 2008 07:03:02PM 2 points [-]

I'm pretty confused by this discussion. People toss out terms like reductionist or anti-reductionist, and I can't even tell what they disagree about.

Here's what I know:

1) There are quarks and electrons, maybe some strings too. Nobody seems to dispute the quarks and electrons, at least. There are also clusters of particles.

2) Everything above that level is an abstraction that only exists in our heads. Yeah, those atoms really are near each other, but the only thing that makes them a "computer" is that we use them for computing. Same applies to brains and minds.

3) Still, calling a spade a spade is useful, so we do it. Not because it's "really" a spade, but because we can't reason quickly about innumerable swarms of quarks.

And that is all. Call it reductionism, call it anti-reductionism, that's all there is to it. There are no spadetrons, no mindtrons and (so far) no computrons.

So, what is the dispute over?

Comment author: Dan3 30 March 2008 07:29:13PM 0 points [-]

Dan - I don't know what "emergent property" or "complex system" are supposed to mean, but Unknown got "bridging law" just right. Granted, it's one thing to assert there's a bridging law, and another to actually provide one.

To say that their might be a "bridging law" without naming any of its properties is to say nothing at all. It's like saying that there might be a thermodynamic law or a falling law, but you have no idea what it might be. It can't be measured or seen, only imagined. It might as well be voodoo, because it has no explanatory power. "Emergent property" and "complex system" are examples of similar terms purported to describe how consciousness could arise, which ... also mean nothing at all*. They're buzzwords, one and all. Unfamiliar examples may have hindered communication on that point. We don't actually know anything about consciousness and none of these terms help that.

Eliezer grants the same point with regards to reductions. The difference between our views is that he thinks the reduction is logically necessary; that there is no sense to be made of the idea of a 'zombie' world physically identical to ours but lacking consciousness. I think that's plainly false. There's nothing incoherent about the idea of zombies. So the admitted link between the physical and phenomenal facts is merely contingent (taking the form of a natural law, rather than a reductive analysis).

Have you been reading Plato? This feels Platonic. You do realize that by saying you can be a "zombie" without physical changes, you automatically bring in a non-physical "consciousness"? Anchoring it to a physical brain doesn't help much. There is a ghost in your machine, even if it does need the machine. Your machine is haunted. I don't know precisely what's haunting it or how many hit dice it has, because "bridging properties" are a little vague for my taste. I am glad, however, to have been assured that successful philosophers can imagine them with ease. I'm also glad that your ghost is completely attached to your brain exactly like a reductionist consciousness would be, because full-blown dualism is harder to work with.

How does changing brain-based accounts of the mind from "reductive analysis" to "natural law" fix the counterintuitiveness of consciousness? Does "natural law" mean "magic"- and if not, what makes it different? How do we find out about natural laws, and what do they do? What, in essense, is gained by prefixing with "psycho-" onto "physical"?

In keeping with my own neo-Platonic leanings, I'd suggest your ghost and/or bridging law is likely an obscenely complex mathematical - or if you prefer, computational - object. It's some kind of madness to require the world's most powerful supercomputer to have some non-physical and/or dualistic properties for it to do counterintuitive and incredible things. I mean, it's a human brain, and more energy and time has been poured into designing it than is either decent or right. It's arguably more complicated than every artificial thing our species has ever made put together, including tax codes. If you can't coax some odd things out of it without resorting to dualism, you're doing it wrong. Any kind of dualism or "bridging law" is fundamentally unnecessary. That's not to say it's definitely wrong, but it's not necessary to account for the fact that consciousness is odd.

I also happen to think philosophical zombies are logically impossible, but that's me.

P.S. You've been reading too many straw men. I certainly don't think "there's a soul floating around communing with the brain". Follow the links in my earlier comment.

Myeah, sorry. The "floating around communing" was in response to an interjection recommending a parapsychology book a ways back.

*"complex system" occasionally does mean something, but usually not when it's being used to refer to minds.

P.S.: It's about dualism, Tiiba. It's not quite Cartesian, but it's still some sort of semi-dualism.

Comment author: Paul_Gowder 30 March 2008 07:41:58PM 1 point [-]

Although I prefer an even weaker kind of scientism: scientism'': an ontological claim is boring if it has no scientific implications. By boring, I mean, tells us nothing relevant to practical reason. Which is why I'm happy to take Richard's property dualism: I accept scientism'', ergo, it doesn't matter.

Comment author: Meta_And_Meta2 30 March 2008 08:51:49PM 1 point [-]

"Yes and when I hit my radio with a rock it might stop working, change the station, if I rip out transistors it might make the sound distorted, etc. That really doesn't prove that the song is stored inside the radio, does it?"

Pace Dan, above, it would not be "parsimonious" to assume the song is "stored in the radio." Even assuming complete naivete about how radios work, it would be relatively easy to show that the songs are (in some mysterious way) coming from some outside source. (For example, you could compare the performance of two identical radios as one is systematically banged up -- although just the fact that two identical radios set next to one another play the same content in perfect simultaneity in itself would be suggestive.)

What's fatal to the analogy, then, is that while physical abuse to your radio doesn't qualitatively affect the radio transmissions, physical abuse to your head does qualitatively affect your mind.

Comment author: Richard4 30 March 2008 08:59:26PM 0 points [-]

Eliezer - all your last comment says is that if I'm suffering from a misunderstanding, then my conclusions won't follow. Well, duh. (See also my response to Robin above.) This doesn't advance the dialectic one iota, unless you can also support the antecedent claim.

Note that my fundamental premise is not, "I think the zombie world is coherently conceivable." Nothing of interest follows from the fact that I have an opinion, since the opinion might be baseless (as you've repeatedly pointed out). Instead, my basic premise is that the zombie world is coherently conceivable (i.e. without the sort of finger-hand misunderstanding that might make a scenario seem conceivable when in fact it's incoherent). You haven't said a word that bears on the truth of this premise. All you've said is that ignorance might lead one to believe it even if it were false. But that is no reason to think that it is false.

Poke - there's no "fallacy" involved in inferring that philosophy isn't nonsense from the fact that the denial of this claim is self-defeating. Proof by contradiction is a straightforwardly valid inference. Now, I might grant you that one doesn't need to reason well to communicate. But philosophy = reasoning, so one does need to philosophize to reason well.

Caledonian - I addressed all that in my linked posts (see esp. 'Why do you think you're conscious?'). Please read my arguments before accusing me of incoherence.

Tiiba - the dispute is whether it's logically coherent to have a world physically identical to ours but lacking consciousness, or whether the physical facts strictly entail the phenomenal facts.

Dan - We have different projects; I'm not trying to "fix the counterintuitiveness of consciousness." I'm interested in whether it is in principle susceptible to physical reduction. (We can answer these sorts of questions by understanding alone. I don't need to do science in order to appreciate the conditional that if physical investigation reveals particles that play such-and-such a role, then objects such as hands will be reducible to said arrangements of particles. There is no coherently conceivable 'hand-zombie' world, analogous to the phenomenal-zombie world, that is identical to ours in all matters of fundamental physics, but somehow lacking in hands.)

Incidentally, I agree that the human brain is capable of amazing computational feats. There are many aspects of its physical functioning that I don't yet understand, though I'm confident future science will make further progress here. None of that is relevant to the present discussion.

Paul: Sure, most fundamental questions - in philosophy and physics alike - do not speak to the practical concerns of folk living everyday lives. (I think this says more about the boringness of the folk than of the fundamental questions, but your tastes may differ...)

Comment author: bigjeff5 02 February 2011 01:37:16AM 0 points [-]

Caledonian - I addressed all that in my linked posts (see esp. 'Why do you think you're conscious?'). Please read my arguments before accusing me of incoherence.

I read your arguments, so is I'll go ahead and accuse you of incoherence. :)

Comment author: Eliezer_Yudkowsky 30 March 2008 09:29:27PM 4 points [-]

Richard sez:

Note that my fundamental premise is not, "I think the zombie world is coherently conceivable." Nothing of interest follows from the fact that I have an opinion, since the opinion might be baseless (as you've repeatedly pointed out). Instead, my basic premise is that the zombie world is coherently conceivable (i.e. without the sort of finger-hand misunderstanding that might make a scenario seem conceivable when in fact it's incoherent). You haven't said a word that bears on the truth of this premise. All you've said is that ignorance might lead one to believe it even if it were false. But that is no reason to think that it is false.

...

Please explain what it means for something to be genuinely conceivable, as opposed to just being conceivable to some particular person.

I'm not sure how I'm supposed to react to this paragraph, frankly. I mean, suppose someone came to me and said: "There are Martians in my nose, therefore extraterrestrial life exists" and I said "Why do you believe there are Martians in your nose?" and he said, "No, I'm not reasoning from my belief that there are Martians in my nose - nothing follows from this, as a belief could be mistaken - I'm reasoning from the fact that there are Martians in my nose."

I mean, how is this not 100% pure naive realism?

Comment author: Richard4 30 March 2008 09:53:26PM 0 points [-]

"Please explain what it means for something to be genuinely conceivable, as opposed to just being conceivable to some particular person."

Conceivable on ideal rational reflection, i.e. without logical error, implicit contradiction, or conceptual ignorance (e.g. failing to realize that hand just means fingers etc.)

"I'm not sure how I'm supposed to react to this paragraph, frankly."

You're supposed to show that my premise is false. We have good reasons for thinking that there are no Martians in my nose. But is there any such reason to think that the zombie scenario is incoherent? Show us the contradiction...

Comment author: Paul_Gowder 30 March 2008 09:53:56PM 0 points [-]

Richard: I'm making a slightly stronger claim, which is that ontological claims with no scientific implications aren't even relevant for philosophical issues of practical reason, so, for example, the question of god's existence has no relevance for ethics (contra, e.g., Kant's second critique). (Of course, to make this fly at all, I'm going to have to say that metaethical positions aren't ontological claims, so I'm probably getting all kinds of commitments I don't want here, and I'll probably have to recant this position upon anything but the slightest scrutiny, but it seems like it's worth considering.)

Comment author: Caledonian2 30 March 2008 09:54:56PM 0 points [-]

Caledonian - I addressed all that in my linked posts

That's nice.

The man who came up with the concept you're bandying around has explicitly said that p-zombies behave identically in every way, not just the ways we can easily perceive. He has even granted that p-zombie versions of himself would make precisely the same arguments.

For this, I consider him a fool. You don't haven't even managed to reproduce his errors correctly - what should I consider you?

Comment author: RobinHanson 30 March 2008 10:24:27PM 0 points [-]

failing to realize that hand just means fingers etc.

Richard, hand only "just means" fingers etc. in a situation where we understand hands very well, and have chosen to think of hands that way. Had we not understand hands as well as we do, we might well conceive of fingers not being parts of hands and so on. I think you are way too quick to conclude that it is "logically impossible to have the fingers and all without a hand."

Comment author: Dan3 30 March 2008 10:41:45PM 0 points [-]

Dan - We have different projects; I'm not trying to "fix the counterintuitiveness of consciousness." I'm interested in whether it is in principle susceptible to physical reduction. (We can answer these sorts of questions by understanding alone. I don't need to do science in order to appreciate the conditional that if physical investigation reveals particles that play such-and-such a role, then objects such as hands will be reducible to said arrangements of particles. There is no coherently conceivable 'hand-zombie' world, analogous to the phenomenal-zombie world, that is identical to ours in all matters of fundamental physics, but somehow lacking in hands.)

Incidentally, I agree that the human brain is capable of amazing computational feats. There are many aspects of its physical functioning that I don't yet understand, though I'm confident future science will make further progress here. None of that is relevant to the present discussion.

Yeah, our projects are actually exactly the same. We're just using completely different tools and/or words. For instance, I am still waiting to figure out how "understanding", "natural law" and "phenomenal" things can be given meaningful weight above voodoo, karmic rebirth, or dreamtime. Being better tailored to our collective cultural background than the alternatives would be is about all it seems to have, as is.

I'm also baffled by the statement that a question about whether the mind can be reduced to the brain could not be informed by the science of how the brain works. Really? I need your tools. I would love to know how things work without having to first understand how they work. I'd also like to mention that the zombie thought experiment has its conclusion embedded in its premises. In order to accept that such zombies are logically coherent, you need to already think that "qualia" have some magical nonphysical quality. It's the definition of circular reasoning, and there's nothing to establish its validity over "hand-zombies" except that it's more appealing to the person thinking it.

Comment author: Richard2 31 March 2008 12:09:00AM 0 points [-]

MTraven - They might have a common structural/functional role. It would be plenty interesting if computing a certain algorithm strictly entailed a certain phenomenal quality (or 'feel').

Dan - I assume that science is essentially limited to third-personal investigation of public, measurable phenomena. It follows that we can expect to learn more and more about the public, measurable aspects of neural functioning. But it would be a remarkable surprise if such inquiry sufficed to establish conclusions about first-personal phenomenology. (In this respect, the epistemic gap between 'physics' and 'phenomenology' mirrors the even more famous gap between 'is' and 'ought'.) Who knows, maybe we'll be surprised? Maybe our current thoughts rest upon severe conceptual errors? Maybe logic is an illusion, and I merely believe in the validity of modus ponens because a demon is messing with my head? We can play "maybe"s all day long, but it doesn't seem very helpful unless you can actually show that a mistake has been made.

Robin - I can't tell what you mean. Are you saying there's a logically possible world that's identical to ours with respect to the arrangement of fingers and palms, etc., but that does not contain any hands? I'm pretty sure that's false: fingers etc. entail hands. But if you can describe a world that serves as a counterexample to this claim, I'd be very curious to hear it.

Alternatively, perhaps you're saying that if we weren't thinking clearly, and didn't really understand the term 'hand', then we might be fooled into believing that hand-zombies were logically possible. (This would be most likely if our 'hand' concept did not explicitly invoke fingers, but rather brought them in implicitly, just as 'water' indirectly reduces to H2O, in virtue of being directly analyzable as 'whatever stuff actually fills the water role'.) I agree with all that, but am yet to be convinced that my judgments about p-zombies rest on any analogous error. [I examine the alleged analogy to conventional a posteriori identities, e.g. water = H2O, here.]

Caledonian - I couldn't care less what you consider me. I'd much rather see you consider my arguments. Maybe then you'd have something of substance to contribute to the conversation. (N.B. I'm well aware that p-zombies are physically - and hence behaviourally - identical to their conscious counterparts. The dispute is over what conclusions we can draw from this.)

Paul - that can't be right. If I could somehow learn (contrary to fact) that animals were p-zombies, i.e. they don't really feel pain despite giving every outward appearance of doing so, that would undermine most arguments for ethical vegetarianism, and instead support the most 'efficient' factory farming practices.

Comment author: komponisto2 31 March 2008 01:19:00AM 0 points [-]

We can play "maybe"s all day long, but it doesn't seem very helpful unless you can actually show that a mistake has been made.

Richard, the burden of proof is on you. You are in effect making the claim that a certain problem ("reduce consciousness to physics") is impossible to solve. But why should we believe that? When all is said and done, you appear to be saying, "because it seems that way". This is where Eliezer comes in.

Comment author: Caledonian2 31 March 2008 01:29:00AM 0 points [-]

I'm well aware that p-zombies are physically - and hence behaviourally - identical to their conscious counterparts. The dispute is over what conclusions we can draw from this.

The obvious conclusion is that 'consciousness' as defined in the thought experiment is meaningless. If the consequences of the presence of consciousness are identical in every way to the consequences of the absence of consciousness, the two states are equivalent, and the word 'consciousness' refers only to the null state.

Comment author: Benquo 31 March 2008 02:45:00AM 0 points [-]

The main difference in my own mind between positing zombies and conscious persons is:
1) the greater sympathy I feel with "real" people, imagining the feelings that correspond to their actions, and
2) the fact that I say that they are, rather than are not, conscious.
Does anyone arguing for the possibility or meaningfulness of a p-zombie materially disagree with what goes on in the mind of someone who supposes a p-zombie or a conscious person? Since if there's no disagreement about that, I don't see how there can be any disagreement on what "p-zombie" means, unless people are arguing about what the word "means" means.
On the other hand, if there is disagreement about what the actual mental content of belief in p-zombies is, maybe we should work that out before talking about whether such a belief is coherent or not.

Comment author: Paul_Gowder 31 March 2008 05:48:00AM 0 points [-]

Richard: the claim I'm trying out depends on us not being able to learn that information, for if we could learn it, the claim would have some observable content, and thereby have scientific implications.

Comment author: Unknown3 31 March 2008 06:24:00AM 0 points [-]

Paul: "we are morally obliged to kill everyone we meet" has no scientific implications, but it definitely has moral implications. To speak plainly, your position is false, and obviously so.

Some children (2-4 years of age) assume that other human beings are zombies, because they do not meet their model of a conscious observer, e.g. adults don't go and eat the ice cream in the freezer, even though no one can stop them, and even though any conscious being would of course eat that ice cream, if it were in its power.

This fact actually is one proof that Caledonian and others are talking nonsense in saying that the zombie world is incoherent; everyone involved in this discussion, including Caledonian, knows exactly what the world would be like if it were a zombie world, and none of us think that the world is actually that way (except maybe poke-- he may actually believe the zombie world is real.)

Comment author: Paul_Gowder 31 March 2008 07:18:00AM 0 points [-]

Unknown: that's not an ontological claim (at least for the dangerous metaethical commitments I mentioned in the caveat above).

Comment author: Caledonian2 31 March 2008 01:02:00PM 1 point [-]

This fact actually is one proof that Caledonian and others are talking nonsense in saying that the zombie world is incoherent; everyone involved in this discussion, including Caledonian, knows exactly what the world would be like if it were a zombie world,

Yes, it would be exactly the same thing it would be if it weren't a zombie world. And that's why the concept of 'zombies' is incoherent.

The mental gymnastics people will go through to avoid confronting this simple and obvious fact are quite extraordinary.

I suspect it's the same reason why people continue to believe in various gods, despite their religions being nonsense, and sometimes will insist that everyone knows that the gods in question exist and are denying their existence out of hate / spite / denial.

Comment author: Ben_Jones 31 March 2008 01:13:00PM 0 points [-]

Unknown - I think we need to clear up our definitions of 'incoherent'. Saying that a zombie world is incoherent doesn't mean that one can't visualise that world. It means that a world isomorphic to our own but 'without consciousness' is not different from our own in any measurable way. Hence the assertion that the the zombie world is interesting/useful is incoherent. Saying that the posulated 'difference' is beyond the realm of science is the religionist stance.

From Richard's blog:

There's no denying that the [zombie] world itself is possible, physically identical to our own, and yet lacking something of a mentalistic sort, however we end up describing it. And that's enough to refute physicalism[.]

Again, please don't base an argument, philosophical or no, on a 'something'. Or at least say what you mean and call it a soul. We don't understand consciousness, that is granted. But 'something' is a mysterious answer to a mysterious question. This sort of thing doesn't have many successful precedents in history.

If you can remove 'consciousness' and nothing changes, what have you done? Maybe the difficult answer to this mysterious question involves facing up to the fact that the mind is just a very complex, naturally arising system made up of physical parts. No magic, no special place in the grand scheme of the universe. Just a high-level, complex system composed of many low-level, simple, physical parts. Imagine what the world would be like if consciousness had already been erased, and we're actually nothing but pretty smart survival machines made out of flesh and bone!

Comment author: Unknown3 31 March 2008 01:44:00PM 0 points [-]

Ben, what do you mean by "measurable"? In the zombie world, Ben Jones posts a comment on this blog, but he never notices what he is posting. In the real world, he knows what he is posting. So the difference is certainly noticeable, even if it isn't measurable. Why isn't "noticeable" enough for the situation to be a useful consideration?

Comment author: michael_vassar 31 March 2008 07:17:00PM 0 points [-]

Poke: Are you sure about mineralogy and physics as foundations of modern geology?

Patrick:

I agree that something roughly along the lines of what you are discussing can be done and is unavoidable. I am primarily attempting to refute the proposal that it is or can be corrected to become Bayesian, and hence the proposal that the process that we use to do things like this stands with the same sort of logical foundations as Bayesian reasoning does. It definitely seems to me that strictly speaking, once you remove logical omniscience, unless you replace it with some very specific abstraction (most of which have their own problems) you need to assign probabilities to "The RH can be proved", "The RH can be disproved", "The RH is undecidable from ZFC", "The RH can be proved AND the RH can be disproved", "The RH can be proved AND the RH can be disproved AND The RH is undecidable from ZFC" "The RH can be disproved AND The RH is undecidable from ZFC" etc. In practice we can apportion zero probability to the latter cases, but only conditional upon the quality of our reflection being perfect, which we know to be false, and only after SOME reflection. It seems to me that as we assign probabilities we have to do reflection that moves our estimates continually.

Comment author: Caledonian2 31 March 2008 08:39:00PM 0 points [-]

I was a bit of an ass earlier. I apologize, I'll try to actually address arguments rather than flinging snide remarks at people.

[EDIT - This does not appear to be Caledonian, but someone else posing as him, namely "varkanut@hotmail.com" which is not Caledonian's usual email address. - Eliezer.]

Comment author: Caledonian2 01 April 2008 12:30:00AM 1 point [-]

In the zombie world, Ben Jones posts a comment on this blog, but he never notices what he is posting.

Um, no, this is wrong.

I wouldn't expect you to take my word for this, but Chalmers himself has said that's not the case. P-zombies behave exactly the same way as people with consciousness do in all ways, so zombie-Ben-Jones' eyes pick up visual data, his brain contains a representation of what he has done and what he is seeing, and he could provide just as much of a reasoned and intelligent discussion of his positions as you'd otherwise expect.

You are not defending Chalmers' actual hypothesis. You are defending a much more intuitively-appealing and defensible position (which as it happens is still wrong, but that's another argument and will be had another day).

P-zombies will reason. P-zombies will claim to have 'experiences' (at least some of them will, anyway), and (some) will discuss how those experiences are not communicable and indescribable, etc. etc. They will not merely be identical to our crude human perceptions. They will not only be identical to the limits of our ability to measure. They will act precisely the same in all ways.

Chalmers argues that it is meaningful to postulate a property such entities would lack that does not affect causality in any way. Don't call it 'conscious experience' if you're hung up on that term - replace it with 'fitzgoanth' if you wish.

P-zombies behave identically in every way to people with fitzgoanth, except that they lack fitzgoanth, and no possible observation of how they act or how they are composed can lead someone to conclude that someone possesses or lacks fitzgoanth. Saying that someone has fitzgoanth does not lead to different conclusions than denying that someone has fitzgoath.

Comment author: GeniusNZ2 01 April 2008 06:19:00AM 0 points [-]

A non reductionist might talk about X where X is specifically defined as 'stuff that cannot be reduced'. The reductionist hears the term X and starts to argue how it can be reduced. Point is that the non-reductionist is fundamentally talking about something different.

the solution is that one can use a on reductionist framework to consider the issue (with an associated shift in definitions of words etc) and one can use a reductionist framework or one can take a position somwhere in the middle. In my opinion the reductionist one is more useful - but if the objective is to "understand the non reducible nature of the soul" (trying to be extreme) or anything along those lines then I guess non reduction might be a way to go.

Similarly, to a non-reductionist a world which is identical but with no qualia is an interesting topic and is conceivable - to a reductionist it may be 'inconceivable'. Just a different definition of the fairly flexible thing 'conceivability'.

mtraven creates a good example,
it would seem mt doesn't seem to care about reductionism. Effectively saying it achieves nothing. On the other side a reductionist would wonder what he was going to achieve via analysis of mind without any sort of reduction.

Similarly we have a semantic debate about if hands without fingers are possible - well to some people it is and some it isn't depending on how they define hands - and whether that should or should not be the case is a pragmatic matter.

So in a fairly pure form you could have a person who denies that 2 is reducible to 1+1 and that 2 can exist without 1 - because he understands the concept in that way. Another person may say thats 2 is only 1+1 and that there is nothing theoretically interesting in the change entailed by having (1+1) appear everywhere that 2 is now.

Comment author: omigod_i've_forgotten_my_name 01 April 2008 09:13:00PM 0 points [-]

Richard: Conceivable on ideal rational reflection, i.e. without logical error, implicit contradiction, or conceptual ignorance (e.g. failing to realize that hand just means fingers etc.)

Conceptual ignorance? Do you have to show such freedom from contradiction, or do your opponents have to show such a contradiction? Either would require you to state the concepts involved in a perfectly logical and complete form. So, what is the physical, precisely? (If it includes QM and GR then there is probably a contradiction.)

Comment author: bigjeff5 02 February 2011 02:54:30AM 2 points [-]

People interested in the discussion between Eliezer and Richard might find this Wikipedia article interesting: Depersonalization Disorder

Essentially, people behave as they otherwise would, except they don't have a sense of "self-awareness". That is, they did something, and they know they did something, but it doesn't feel as though it was them who did the thing. Often people feel as though they are automata, pre-programmed to respond to certain stimuli, but that there is no "self" driving them.

The disorder also tends to cause its inverse, which is derealization. That is, the individual perceives himself to be real, but nothing external is real.

This effect can be generated with drugs, and it can also be treated with drugs. This suggests to me that the entire "sense of self" is caused by a chemical interaction within the brain.

Comment author: TheOtherDave 02 February 2011 03:29:47AM 1 point [-]

Ayup. I experienced a limited form of this a couple of years ago... it was creepy.

Comment author: anon895 02 February 2011 04:36:11AM *  0 points [-]

Not wanting to open a possibly long article: is that the same thing as dissociation? Is dissociation the symptom and depersonalization a cluster of symptoms that includes it?

Comment author: bigjeff5 02 February 2011 05:13:07PM *  2 points [-]

Depersonalization is a type of dissociation disorder, yes. It's in the same class of disorder as multiple personalities - or Dissociative Identity Disorder.

And I think the discussions between Richard, Eliezer, and Robin, among others, are worth reading. Richard argues, in a nutshell, that the mind is more than just the brain, that there is something else that creates the mind. Eliezer and Robin argue that he his making the same mistakes that he has been describing in the Mysterious Answers to Mysterious Questions sequence. That's what the "zombie world" is all about - if a world consists of humans who are in every way exactly the same as ours minus whatever ephemeral thing it is that Richard says completes "consciousness", Richard argues these zombies will not be conscious, and Eliezer argues that they will be, because they are made of all the same things that we are.

Comment author: RogerS 06 April 2013 07:53:29PM 0 points [-]

...much later... The thing that puzzles me about this post is that no attention is paid to context.

I had an operation last year to my right index finger. It was carried out by a hand surgeon. I used those terms because it was rather important which finger was operated on, and because the medical specialism relates to any part of the hand indifferently.

A trivial example, of course, but it illustrates the point, which applies also to much more complex issues, that the appropriate choice of "model level" (or other meta-model feature) to best represent the aspect of reality that matters depends on the context (and especially on the purpose). The difficulty begins, IMHO, when people insist on using the same model or meta-model whatever the context.

Most commenters on this post seem entirely wrapped up in the mind/brain question. That isn't the only question for rationalists to have a view about! They don't seem to be aware that arguments about the usefulness and limits of reductionism also continue in many other fields. The problem is probably that concepts like emergence are used in the mind-brain debate as an excuse for vitalism. But that is really a special case, just because minds are the things that are conducting this debate. In other fields emergence can be a useful concept. In other words I can claim that emergence is useful (in some senses anyway) without believing this has anything to do with consciousness.

Comment author: Black_Lemon 22 July 2015 04:50:04PM *  1 point [-]

EDIT: Typos.

I have been reading some of the sequences, and this entry shocked me a lot.

If the reductionist thesis is "we use multi-level models for computational reasons, but physical reality has only a single level", then what kind of evidence could support it against the thesis "we use multi-level models for computational reasons AND physical reality has multiple levels?" (let me call it 'anti-reductionist thesis' regardless of what actual anti-reductionists defend). I just can't think of how the world would be different if physical reality had multiple levels than if it had only one level.

In other words, the reductionist thesis, as it is presented here, does not lead me to anticipate differently than the anti-reductionst thesis. Accepting it just generates a floating belief, and as a result, I reject the reductionist thesis, and you should do the same.

Am I wrong? And why?

Comment author: hyporational 22 July 2015 11:20:15PM *  1 point [-]

EDIT: this is now pretty much retracted, see the following thread.

If the reductionist thesis is "we use multi-level models for computational reasons, but physical reality has only a single level", then what kind of evidence could support it against the thesis "we use multi-level models for computational reasons AND physical reality has multiple levels?"

Lower level models are more accurate than abstract models, and you can observe the consequences of this on multiple levels of abstraction. Therefore if physical reality has multiple levels then they must be incompatible and parallel in a very peculiar way. This makes the idea more complex and therefore less probable than the reductionist thesis.

Tabooing reality might make things a bit clearer.

Comment author: EHeller 23 July 2015 12:09:12AM 1 point [-]

The whole point of the renormalization group is that lower level models aren't more accurate, the lower level effects average out.

The multiple levels of reality are "parallel in a peculiar way" governed by RG. It might be "more complex" but it's also the backbone of modern physics.

Comment author: hyporational 23 July 2015 07:00:15AM *  0 points [-]

The whole point of the renormalization group is that lower level models aren't more accurate, the lower level effects average out.

I tried to read about RG but it went way over my head. Is the universe in principle inexplicable by lower level theories alone according to modern physics? Doesn't "averaging out" lose information? Are different levels of abstraction considered equally real by RG? Does this question even matter or is it in the realm of unobservables in the vein of Copenhagen vs MW interpretation?

Comment author: EHeller 23 July 2015 07:34:05AM 4 points [-]

The point of RG is that "higher level" physics is independent of most "lower level" physics. There are infinitely many low level theories that could lead to a plane flying.

There are infinitely many lower level theories that could lead to quarks behaving as they do,etc. So 1. you can't deduce low level physics from high level physics (i.e. you could never figure out quarks by making careful measurements of tennis balls), and you can never know if you have truly found the lowest level theory (there might be a totally different theory if you only had the ability to probe higher energies).

This is super convenient for us- we don't need to know the mass of the top quark to figure out the hydrogen atom,etc. Also, it's a nice explanation for why the laws of physics look so simple- the laws of physics are the fixed points of renormalization group flow.

Comment author: hyporational 23 July 2015 08:01:35AM *  0 points [-]

Thanks, my reality got just a bit weirder. It's almost as if someone set up a convenient playground for us, but that must be my apophenia speaking. If there are infinite possibilities of lower level theories, are successful predictions in particle physics just a matter of parsimony? Is there profuse survival bias when it comes to hyping successful predictions?

Comment author: EHeller 23 July 2015 03:57:24PM *  2 points [-]

I think I'm communicating a little poorly. So start with atomic level physics- it's characterized by energy scales of 13.6 eV or so. Making measurements at that scale will tell you a lot about atomic level physics, but it won't tell you anything about lower level physics- there is an infinite number of of lower level physics theories that will be compatible with your atomic theory (which is why you don't need the mass of the top quark to calculate the hydrogen energy levels- conversely you can't find the mass of the top quark by measuring those levels).

So you build a more powerful microscope, now you can get to 200*10^6 eV. Now you'll start creating all sorts of subatomic particles and you can build QCD up as a theory (which is one of the infinitely many theories compatible with atomic theory). But you can't infer anything about the physics that might live at even lower levels.

So you build a yet more powerful microscope, now you can get 10^14 eV, and you start to see the second generation of quarks,etc.

At every new level you get to, there might be yet more physics below that length scale. The fundamental length scale is maybe the planck scale, and we are still 13 orders of magnitude above that.

Edit: this author is sort of a dick overall, but this was a good piece on the renormalization group- http://su3su2u1.tumblr.com/post/123586152663/renormalization-group-and-deep-learning-part-1

Comment author: hyporational 23 July 2015 07:43:18PM 1 point [-]

I think I'm the one communicating poorly since it seems I understood your first explanation, thanks for making it sure anyways and thanks for the link!

When I was wondering about successful predictions in particle physics, I was in particular thinking about Higgs boson. We needed to build a massive "microscope" to detect it, yet could predict its existence four decades ago with much lower energy scale equipment, right?

Comment author: EHeller 24 July 2015 04:10:34AM 3 points [-]

The existence of the Higg's is one of the rare bits of physics that doesn't average out under renormalization.

The reason is that the Higgs is deeply related to the overall symmetry of the whole standard model- you start with a symmetry group SU(2)xU(1) and then the Higgs messes with the symmetry so you end up with just U(1) symmetry. What the theory predicts is relationships between the Higgs, the W and Z boson, but not the absolute scale. The general rule is RG flow respects symmetries, but other stuff gets washed out.

This is why the prediction was actually "at least 1 scalar particle that interacts with W and Z bosons". But there are lots of models consistent with this- it could have been a composite particle made of new quark-like-things (technicolor models), there could be multiple Higgs (2 in SUSY, dozens in some grand unified models),etc. So it's sort of an existence proof with no details.

Comment author: Black_Lemon 23 July 2015 01:42:31PM *  0 points [-]

Even if the argument "Occam's Razor says that since reality having only one level is simpler than reality having multiple levels, then the first option is more likely to be true." was valid, there is a problem.

Contrarily to other contexts where Occam's Razor is actually useful, none of these options lead us to anticipate differently under any circumstance, so the rational thing to do here is not to apply Occam's Razor, but to reject the question "Does physical reality have one level or multiple levels?"

Edit: Note that I did not mean to say that you should not apply Occam's Razor at all in this scenario. Perhaps, given the hypothesis that reality has multiple levels, Occam's Razor makes certain phenomena more likely, and observations regarding these phenomena could be used to argue for or against the reductionist thesis. The point is that I cannot find examples of such phenomena, specially if the kind of multiple levels that we are talking about are purely physical.

Comment author: Black_Lemon 23 July 2015 02:28:48PM *  0 points [-]

Wait. Perhaps one of such predictions would be that we should find universal laws involving higher-level entities, while it seems that at that level, we only find ceteris paribus laws. By contrast, at the lower level, we do find universal laws. This should be evidence in favour of the reductionist thesis.

Which would indicate that I was wrong in my initial claim.

Comment author: hyporational 24 July 2015 03:13:20AM *  1 point [-]

Actually when I first responded to you I was thinking about biology, psychology and such as the higher level. In this case the claim seems to make sense. However, if I understood EHeller correctly, this doesn't hold water inside the realm of modern physics. Besides, we can in principle never know if we're at the lowest level.

Comment author: Chriswaterguy 11 May 2016 10:45:11AM *  0 points [-]

When you pick up a cup of water... the force exerted by your hand must be zero.

Unless you are holding the cup up, supporting it against the force of gravity.

Comment author: Good_Burning_Plastic 11 May 2016 12:03:00PM 0 points [-]

You're missing the point of that example.