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It's not like anything to be a bat

15 Post author: Yvain 27 March 2010 02:32PM

...at least not if you accept a certain line of anthropic argument.

Thomas Nagel famously challenged the philosophical world to come to terms with qualia in his essay "What is it Like to Be a Bat?". Bats, with sensory systems so completely different from those of humans, must have exotic bat qualia that we could never imagine. Even if we deduce all the physical principles behind echolocation, even if we could specify the movement of every atom in a bat's senses and nervous system that represents its knowledge of where an echolocated insect is, we still have no idea what it's like to feel a subjective echolocation quale.

Anthropic reasoning is the idea that you can reason conditioning on your own existence. For example, the Doomsday Argument says that you would be more likely to exist in the present day if the overall number of future humans was medium-sized instead of humongous, therefore since you exist in the present day, there must be only a medium-sized number of future humans, and the apocalypse must be nigh, for values of nigh equal to "within a few hundred years or so".

The Buddhists have a parable to motivate young seekers after enlightenment. They say - there are zillions upon zillions of insects, trillions upon trillions of lesser animals, and only a relative handful of human beings. For a reincarnating soul to be born as a human being, then, is a rare and precious gift, and an opportunity that should be seized with great enthusiasm, as it will be endless eons before it comes around again.

Whatever one thinks of reincarnation, the parable raises an interesting point. Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal.

The phrase "for me to be an animal" may sound nonsensical, but "why am I me, rather than an animal?" is not obviously sillier than "why am I me, rather than a person from the far future?". If the doomsday argument is sufficient to prove that some catastrophe is preventing me from being one of a trillion spacefaring citizens of the colonized galaxy, this argument hints that something is preventing me from being one of a trillion bats or birds or insects.

And this could be that animals lack subjective experience. This would explain quite nicely why I'm not an animal: because you can't be an animal, any more than you can be a toaster. So Thomas Nagel can stop worrying about what it's like to be a bat, and the rest of us can eat veal and foie gras guilt-free.

But before we break out the dolphin sausages - this is a pretty weird conclusion. It suggests there's a qualitative and discontinuous difference between the nervous system of other beings and our own, not just in what capacities they have but in the way they cause experience. It should make dualists a little bit happier and materialists a little bit more confused (though it's far from knockout proof of either).

The most significant objection I can think of is that it is significant not that we are beings with experiences, but that we know we are beings with experiences and can self-identify as conscious - a distinction that applies only to humans and maybe to some species like apes and dolphins who are rare enough not to throw off the numbers. But why can't we use the reference class of conscious beings if we want to? One might as well consider it significant only that we are beings who make anthropic arguments, and imagine there will be no Doomsday but that anthropic reasoning will fall out of favor in a few decades.

But I still don't fully accept this argument, and I'd be pretty happy if someone could find a more substantial flaw in it.

Comments (189)

Comment author: Psychohistorian 27 March 2010 06:17:38PM 15 points [-]

Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal.

The anthropic principle creeps in again here, and methinks you missed it. The ability to make this argument is contingent upon being an entity capable of a certain level of formal introspection. Since you have enough introspection to make the argument, you can't be an animal. In your next million lives, so to speak, you won't be able to make this argument, though someone else out there will.

Comment author: Jonii 27 March 2010 03:42:09PM 12 points [-]

If you'd be any other animal on Earth, you wouldn't be considering what it would be like to be something else. Doomsday argument and arguments like it are usually formulated in a way "Of all the persons that could reason like me, only this small percentage ever were wrong". When animals are prevented, due to their neurological limitations, from reasoning as necessiated by the argument, they're not part of this consideration.

This doesn't mean that they're not sentient, it just means that by thinking about anthropic problems you're part of much narrower set of beings than just sentient ones.

Comment author: Yvain 27 March 2010 05:23:28PM 7 points [-]

Why not limit the set of people who could reason like me to "people who are using anthropic reasoning" and just assume people will stop using anthropic reasoning in the next hundred years? Is this a reductio ad absurdum, or do you think it's a valid conclusion?

Comment author: Jack 28 March 2010 02:30:00AM *  6 points [-]

Perhaps the fact that we are so confused by anthropic reasoning is a priori evidence that we are a very early anthropic reasoners and thus the Doomsday argument is false. Further, not every human is an anthropic reasoner. If the growth rate of anthropic reasoners is less than the growth rate of humans we should then extend the estimation of the lifespan of a human race with anthropic reasoners (and of course this says nothing about the lifespan of humanity without anthropic reasoners).

A handful of powerful anthropic reasoners could enforce a ban on anthropic reasoning: burning books, prohibiting it's teaching and silencing those who came to be anthropic reasoners on their own. If within two generations we could stabilize the anthropic reasoner population at around 35 (say 10 enforcing, 25 to account for enforcement failure) with life spans averaging 100 years that would put us in the final 95% (I think, anyone have an educated estimate of how many anthropic reasoners there have been up to this point in time?) until a permanent solution was reached or humanity began spreading and we would need at least one enforcer for every colony-- but given optimistic longevity scenarios we could still keep the anthropic reasoner population to a minimum. The permanent solution is probably obvious: A singleton could enforce the ban by itself and make itself the last or at least close to last anthropic reasoner in the galaxy.

The above strikes me as obviously insane so there has to be a mistake somewhere, right?

Comment author: Strange7 14 January 2011 12:56:23PM 1 point [-]

Maybe somebody will just come up with an elegant explanation of the underlying probability theory some time in the next few years, it'll go viral among the sorts of people who would otherwise have attempted anthropic reasoning, and the whole thing will go the way of geocentrism, but with fewer religiously-motivated defenders.

Comment author: JGWeissman 28 March 2010 03:50:41AM 1 point [-]

If within two generations we could stabilize the anthropic reasoner population at around 35 (say 10 enforcing, 25 to account for enforcement failure) with life spans averaging 100 years that would put us in the final 95% ...

That sounds like something Evidential Decision Theory would do, but not Timeless or Updateless Decision Theories. Unless you think that reaching a certain number of anthropic reasoners would cause human extinction.

Comment author: Jack 28 March 2010 05:36:32AM 2 points [-]

Hmmm. Yes thats right, as far as I understand those theories at least. I guess my point is that something seems very wrong with an argument that makes predictions but offers nothing in the way of causal regularities whose variables could in principle be manipulated to alter the result. It isn't even like seen barometer indicate low pressure and then predicting a storm (while not understanding the variable that lead to the correlation of barometers indicating low pressure and storms coming): there isn't even any causal knowledge involved in the Doomsday argument afaict. Note that this isn't the case with all anthropic reasoning, it is peculiar to this argument. The only way we know of predicting the future is by knowing earlier conditions and rules governing those conditions over time: the Doomsday argument is thus an entirely knew way of making predictions. This suggests to me something has to be wrong with it.

Maybe the self-indication assumption is the way out, I can't tell if I would have the same problem with it.

Comment author: Jordan 27 March 2010 06:52:19PM 1 point [-]

You know that you are using anthropic reasoning, so you can limit yourself to the group of people using anthropic reasoning. You likewise know that your name is Yvain... so you can limit yourself to the group of people named Yvain?

Comment author: Jonii 27 March 2010 05:36:20PM *  1 point [-]

"Why not limit the set of people who could reason like me to "people who are using anthropic reasoning" and just assume people will stop using anthropic reasoning in the next hundred years?"

That's known as the Doomsday argument, as far as I can tell.

My point, in a bit simplifying way, is that anthropic reasoning is only applicable to beings are capable of anthropic reasoning. If you know that there are billion agents, of which one thousand are capable of anthropic reasoning, and you know that of anthropic reasoners 950 are on island A and 50 are on the B, and all the non-anthropic reasoners are on island B, you know, based on anthropic reasoning, that you're on the island A 95% certainly. The rest of the agents simply don't matter. You can't conclude anything about those beyond that they're most likely not capable of anthropic reasoning

Comment author: khafra 28 March 2010 02:28:11AM 0 points [-]

What happens if we replace "capable of anthropic reasoning" to "have considered the anthropic doomsday argument"? As far as I can tell, it becomes a tautology.

Comment author: Jonii 28 March 2010 12:25:53PM 0 points [-]

I'm not sure, but it seems that your tautology-way of putting it is simply more accurate, at the cost that using it requires more accurate a priori knowledge.

Comment author: Unknowns 30 March 2010 05:16:22PM 0 points [-]

I argued before -- in the discussion of the Self-Indication Assumption -- that this is exactly the right anthropic reference class, namely people who make the sorts of considerations that I am engaging in. However, that doesn't show that people will just stop using anthropic reasoning. It shows that this is one possibility. On the other hand, it is still possible that people will stop using such reasoning because there will be no more people.

Comment author: PhilGoetz 27 March 2010 09:27:36PM *  11 points [-]

That's an interesting observation.

There's a problem in assuming that consciousness is a 0/1 property; that you're either conscious, or not.

There's another problem in assuming that YOU are a 0/1 property; that there is exactly one atomic "your consciousness".

Reflect on the discussion in the early chapters of Daniel Dennet's "Consciousness Explained", about how consciousness is not really a unitary thing, but the result of the interaction of many different processes.

An ant has fewer of these processes than you do. Instead of asking "What are the odds that 'I' ended up as me?", ask, "For one of these processes, what are the odds that it would end up in me, rather than in an ant?"

According to Wikipedia's entry on biomass, ants have 10-100 times the biomass of humans today.

According to Wikipedia's list of animals by neuron count, ants have 10,000 neurons.

According to that page, and this one, humans have 10^11 neurons.

Information is proportional not to the number of neurons, but to the number of patterns that can be stored in those neurons, which is likely somewhere between N and N^2. I'm gonna call it NlogN.

I weigh as much as 167,000 ants. Each of them has ~ 10,000 log(10,000) bits of info. I have ~ 10^11 log(10^11) bits of info. I contain as much information as 165 times my body-mass worth of ants.

So if we ignore how much longer ants have lived than humans, the odds are better that a random unit of consciousness today would turn up in a human, than in an ant.

(Also note that we can only take into account ants in the past, if reincarnation is false. If reincarnation is true, then you can't ask about the chances of you appearing in a different time. :) )

If you're gonna then say, "But let's not just compare ourselves to ants; let's ask about turning up in a human vs. turning up in any other species", then you have the dice-labelling problem argued below: You're claiming humans are the 1 on the die.

Comment author: wnoise 30 March 2010 06:38:19PM 4 points [-]

Information is proportional not to the number of neurons, but to the number of patterns that can be stored in those neurons,

No, it's proportional to the log of the number of patterns that can be (semi-stably) stored. E.g. n bits can store 2^n patterns.

which is likely somewhere between N and N^2. I'm gonna call it NlogN.

I'd like to see a lot more justification for this. If each connection were binary (it's not), and connections were possible between all N neurons (they're not), than we would have N^2 bits.

Comment author: PhilGoetz 30 March 2010 07:11:55PM *  2 points [-]

No, it's proportional to the log of the number of patterns that can be (semi-stably) stored. E.g. n bits can store 2^n patterns.

Oops! Correct. That's what I was thinking, which is why I said info NlogN for N neurons. N neurons => max N^2 connections, 1 bit per connection, max N^2 bits, simplest model.

The math trying to estimate the number of patterns that can be stored in different neural networks is horrendous. I've seen "proofs" for Hopfield network capacity ranging from, I think, N/logN to NlogN.

Anyway, it's more-than-proportional to N, if for no other reason than that the number of connections per neuron is related to the number of neurons. A human neuron has about 10,000 connections to other neurons. Ant neurons don't.

Comment author: SilasBarta 30 March 2010 06:10:43PM *  3 points [-]

Humans are more analogous to an ant colony than to an individual ant, so that's where you should make the comparison: to a number of ant colonies with ant mass equal to your mass. Within each colony, you should treat each ant as a neuron in a large network, meaning you multiply the ant information not by the number of ants Na, but by Na log Na.

Assume 1000 ants/colony. You weight as much as 167 colonies. Letting N be the number of neurons in an ant (and measuring in Hartleys to make the math easier), each colony has

(N log N) (Na log Na)
= (1e4 log 1e4) (1e3 log 1e3) = 1.2e8 H

Multiplying by the number of colonies (since they don't act like a mega-colony) gives

1.2e8 H * 167
=2e10 H

This compares with the value for humans:

1e11 log 1e11
1.1e12 H

So that means you have ~55 times as much information per unit body weight, not that far from your estimate of 165.

I don't know what implications this calculation has for the topic, even assuming it's correct, but there you go.

Comment author: PhilGoetz 30 March 2010 07:15:53PM 0 points [-]

Within each colony, you should treat each ant as a neuron in a large network

Good point!

Comment author: RobinHanson 27 March 2010 11:55:28PM 3 points [-]

This is a very intriguing line of thought. I'm not sure it makes sense, but it seem worth pondering further.

Comment author: Yvain 28 March 2010 01:32:44PM 0 points [-]

I weigh as much as 167,000 ants. Each of them has ~ 10,000 log(10,000) bits of info. I have ~ 10^11 log(10^11) bits of info. I contain as much information as 165 ants.

I'm not following your math here, and I'm especially not following the part where if a person contains as much information as 165 ants and there are 1 quadrillion ants and ~ 10 billion people, a given unit of information is more likely to end up in a human than in an ant. And since we do believe reincarnation is false, it's much worse than that, since ants have been around longer than humans.

Also, I have a philosophical objection with basing it on units consciousness. If we're to weight the chances of being a certain animal with the number of bits information they have, doesn't that imply we're working from a theory where "I" am a single bit of information? I'd much sooner say that I am all the information in my head equally, or an algorithm that processes that information, or at least not just a single bit of it.

Comment author: PhilGoetz 28 March 2010 04:04:12PM *  1 point [-]

Oops; that was supposed to say, "I contain as much information as 165 times my body-mass in ants".

I'm kinda disappointed that your objection was that the math didn't work, and not that I'm smarter than 165 ants. (I admit they are winning the battle over the kitchen counter. But that's gotta be, like, 2000 ants. Don't sell me short.)

If you want to say that you're all the information in your head equally, then you can't ask questions like "What are the odds I would have been an ant?"

Comment author: JohannesDahlstrom 29 March 2010 10:10:24PM *  9 points [-]

The probability of a randomly picked currently-living person having a Finnish nationality is less than 0.001. I observe myself being a Finn. What, if anything, should I deduce based on this piece of evidence?

The results of any line of anthropic reasoning are critically sensitive to which set of observers one chooses to use as the reference class, and it's not at all clear how to select a class that maximizes the accuracy of the results. It seems, then, that the usefulness of anthropic reasoning is limited.

Comment author: Mallah 30 March 2010 04:28:01PM 2 points [-]

That kind of anthropic reasoning is only useful in the context of comparing hypotheses, Bayesian style. Conditional probabilities matter only if they are different given different models.

For most possible models of physics, e.g. X and Y, P(Finn|X) = P(Finn|Y). Thus, that particular piece of info is not very useful for distinguishing models for physics.

OTOH, P(21st century|X) may be >> P(21st century|Y). So anthropic reasoning is useful in that case.

As for the reference class, "people asking these kinds of questions" is probably the best choice. Thus I wouldn't put any stock in the idea that animals aren't conscious.

Comment author: AlephNeil 15 May 2010 04:27:46AM 1 point [-]

Just think: In a universe that contains a countable infinity of conscious observers (but finite up to any given moment of time), people's heads would explode as they tried to cope with the not-even-well-defined probability of being born on or before their birth date.

Comment author: PhilGoetz 28 March 2010 12:29:08AM 7 points [-]

Can't I use the same reasoning to prove that non-Americans aren't conscious?

Comment author: JGWeissman 28 March 2010 12:52:58AM 2 points [-]

The anthropic principal only provides between 4 and 5 bits of evidence for this this theory, not nearly enough to support the complexity of the same brain structures being conscious in Americans but not in non-Americans.

Comment author: PhilGoetz 28 March 2010 12:58:09AM 13 points [-]

All right, then. I got 33 bits that says everyone except me is unconscious!

Comment author: bogus 28 March 2010 03:38:25PM -3 points [-]

This is actually a very good point. If the quantum mind hypothesis is false, then either subjective experience doesn't exist at all (which anyone who's reading this post ought to take as an empirically false statement) or solipsism is true and only a single subjective experience exists. 33 bits of info are just not nearly enough to explain how subjective experience is instantiated in billions of complex human brains each slightly different from all others, as opposed to a single brain.

Comment author: PhilGoetz 28 March 2010 04:02:59PM 2 points [-]

If the quantum mind hypothesis is false, then either subjective experience doesn't exist at all (which anyone who's reading this post ought to take as an empirically false statement) or solipsism is true and only a single subjective experience exists.

Why's that?

Comment author: bogus 28 March 2010 04:16:50PM -2 points [-]

Why's that?

Because "I am my brain" is actually an extremely complex hypothesis; you need to relate all of your inner subjective experience to brain states, action potentials, firing patterns and what not. Since all brains are actually slightly different from one another (at least from a purely physical point of view), the hypothesis that other brains also have subjective experience is untenable due to its sheer complexity.

Comment author: [deleted] 28 March 2010 07:12:55PM 4 points [-]

That's like saying that "there is a prime number greater than 3^^^3" is an extremely complex and therefore untenable hypothesis, because such a number needs to be coprime to all of the natural numbers below it.

Every possible way to realize the hypothesis "I am my brain" is extremely unlikely, but there are extremely many ways to realize it. A disjunction of lots of unlikely things need not be unlikely.

Comment author: bogus 28 March 2010 08:30:12PM *  0 points [-]

Every possible way to realize the hypothesis "I am my brain" is extremely unlikely, but there are extremely many ways to realize it.

No, there aren't. The physical state of your brain is known, and (assuming physicalism/epiphenomenalism/property dualism is true) the physical state must explain everything you might claim about your subjective experience. Either you're a p-zombie and do not actually have subjective experience, or this explanation must be evaluated for simplicity on Occam's razor/Solomonoff induction grounds.

Comment author: [deleted] 29 March 2010 02:31:37AM 1 point [-]

You've managed to confuse me. I suspect, though, that this analogy is relevant:

What is the probability that the text between the quotation marks in this paragraph is "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce id velit urna, ac sollicitudin libero. Phasellus ac rutrum nisl. In volutpat scelerisque justo, non congue diam vestibulum sit amet. Donec."? The prior probability of this being true is minuscule, looking something like 10^-60; therefore, you might as well rule it out now.

On the other hand, I suspect that we don't actually disagree at all. After all, you seem to be arguing for a position I agree with; I'm simply not sure whether you're arguing correctly or not.

Comment author: wedrifid 29 March 2010 11:40:27AM 1 point [-]

What is the probability that the text between the quotation marks in this paragraph is "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce id velit urna, ac sollicitudin libero. Phasellus ac rutrum nisl. In volutpat scelerisque justo, non congue diam vestibulum sit amet. Donec."? The prior probability of this being true is minuscule, looking something like 10^-60; therefore, you might as well rule it out now.

Prior to what exactly? I do have a prior for "a randomly generated ascii string of that particular length being the same as the string given". I wouldn't be able to know to use that as the prior unless I have already been given some information. Then there is all the knowledge of human languages and cultural idiosyncracies I happen to have. Which of those am I allowed to consider? It's hard to tell since, well, you've alreay given me the answer. It's a bit post for any 'prior' except meta-uncertainty. I would need a specific counter-factual state of knowledge to be able to give a reasonable prior.

(All of which I believe supports your point.)

Comment author: bogus 29 March 2010 01:09:35PM 0 points [-]

This seems to be a case of extraordinary claims are extraordinary evidence. It's like saying, "well yes, the fact that I have a brain is pretty extraordinary, but so what? I clearly have one". It doesn't distinguish between a Boltzmann brain and a brain arising normally via natural selection. So is your consciousness a Boltzmann consciousness?

Comment author: PhilGoetz 28 March 2010 04:45:51PM 2 points [-]

Since all brains are actually slightly different from one another (at least from a purely physical point of view), the hypothesis that other brains also have subjective experience is untenable due to its sheer complexity.

I don't see any justification for the connecting "since".

Comment author: bogus 28 March 2010 05:58:36PM -1 points [-]

You believe that a single mapping between physical brains and subjective experiences can apply to all humans? What does this mapping look like? How many bits are needed to fully specify it?

Comment author: Nick_Tarleton 28 March 2010 07:06:54PM *  2 points [-]

Is it reasonable to expect me to necessarily be able to answer that question if materialism is true?

(What does the mapping from entangled quantum states to experiences look like?)

Comment author: bogus 28 March 2010 07:37:26PM -2 points [-]

Is it reasonable to expect me to necessarily be able to answer that question if materialism is true?

It's about as reasonable as demanding an account of how the brain can mantain mesoscopic quantum superpositions long enough to influence neural processes.

(What does the mapping from entangled quantum states to experiences look like?)

We don't know, but it's going to be far simpler than a mapping from classical brains.

(For all we know, it could be trivial; perhaps each quale is a GENSYM which maps directly to a basis of the quantum system.)

Comment author: Morendil 28 March 2010 04:18:03PM 0 points [-]

What does that have to do with the quantum mind hypothesis?

Comment author: bogus 28 March 2010 04:29:44PM -1 points [-]

That allows you to replace "I am my brain" with "I am a complex quantum state which is instantiated by my brain; and my inner experience maps directly to this quantum state." Other brains have evolved to maintain quantum states in the same way, hence they also have subjective experience.

Comment author: PhilGoetz 28 March 2010 04:44:54PM 2 points [-]

That doesn't make a difference wrt your argument.

Comment author: Yvain 28 March 2010 01:37:41PM 0 points [-]

Not unless you have a strong reason to privilege the state of being an American as especially interesting. Otherwise, you're in the position Jordan mentioned of just knowing you're in one unexceptional condition out of many.

One thing you could say based on your being an American is that you have weak evidence that America is likely to be one of the more populous countries, and strong evidence that there's no country thousands or billions of times more populous than America. Both conclusions are correct.

And further, if a Luxembourgian posts a reply here saying "My Luxembourgian citizenship disproves the anthropic principle", that doesn't count, because you're not him and he's self-selected by posting here o_O

Comment author: rwallace 28 March 2010 03:21:56PM 1 point [-]

So we seem to have concluded that my Irish citizenship disproves the anthropic principle, and I can know this, but you cannot know it :-)

Comment author: Yvain 28 March 2010 04:08:48PM *  2 points [-]

As a matter of fact, I live in Ireland (although I'm a US citizen). That coincidence probably disproves some sort of important principle right there.

I think you've mentioned before that you live in Dublin; I live in Cork, so sadly we're a little too far to meet up for a chat one night.

Comment author: rwallace 28 March 2010 06:16:12PM 0 points [-]

It probably does :-)

Yeah, a little too far, but let me know if you're going to be in Dublin at any stage, and I'll do likewise if I'm going to be in Cork.

Comment author: Jordan 27 March 2010 08:16:06PM 5 points [-]

Let's look at examples where we know the 'right' answer:

Someone flips a coin. If it's heads they copy you a thousand times and put 1 of you in a green room and 999 of you in a red room. If it's tails they do the opposite.

You wake up in a green room and conclude that the coin was likely tails.

Now assume that in addition to copying you 1000 times, 999 of you were randomly selected to have the part of your brain that remembers to apply anthropic reasoning erased. You wake up in a green room and remember to apply the anthropic principle, but, knowing that you conclude that the group of people like you is only you. Nonetheless you should (I intuitively feel) still conclude the coin was likely tails.

Now assume that instead of random memory erasure, if the coin was heads the people in the red room forget about anthropics, and if the coin was tails the people in the green room forget about anthropics. You wake up in a green room and remember to apply the anthropic principle. Now it matters that you know to use the anthropic principle, and you should conclude with 100% certainty that the coin came up heads.

So, sometimes we need to consider the fact that the other people can apply the anthropic principle, and sometimes we don't need to consider it. I think I've confused myself.

Comment author: AlephNeil 17 May 2010 04:34:35PM *  0 points [-]

Nonetheless you should (I intuitively feel) still conclude the coin was likely tails.

I think your intuitions lead you astray at exactly this point.

Suppose that the 1000 of you are randomly 'tagged' with distinct id numbers from the set {1,...,1000}, and that a clone learns its id number upon waking. Suppose you wake in a green room and see id number 707.

If all the clones remember to apply anthropic reasoning (assuming for argument's sake that my current line of reasoning is 'anthropic') then you can easily work out that the probability of the observed event "number 707 is an anthropic reasoner in a green room" is 1/1000 if coin was heads or 999/1000 if coin was tails.

However, if 998 clones have their 'anthropic reasoning' capacity removed then both probabilities are 1/1000, and you should conclude that heads and tails are equally likely.

Comment author: NihilCredo 17 May 2010 04:47:22PM 0 points [-]

However, if 999 clones have their 'anthropic reasoning' capacity removed then both probabilities are 1/1001, and you should conclude that heads and tails are equally likely.

Are you sure? In the earlier model where memory erasure is random, remembering AR will be an independent event from the room placements and won't tell you anything extra about that.

Comment author: AlephNeil 17 May 2010 04:57:28PM 0 points [-]

Are you sure?

(Note: I got the numbers slightly wrong - the 1001s should have been 1000s etc.)

Yes: If the coin was heads then the probability of event "clone #707 is in a green room" is 1/1000. And since, in this case, the clone in the green room is sure to be an anthropic reasoner, the probability of "clone #707 is an anthropic reasoner in a green room" is still 1/1000.

On the other hand, if the coin was tails then the probability of "clone #707 is in a green room" is 999/1000. However, clone #707 also knows that "clone #707 is an AR", and P(#707 is AR | coin was tails and #707 is in a green room) is only 1/999.

Therefore, P(#707 is an AR in a green room | coin was tails) is (999/1000) * (1/999) = 1/1000.

Comment author: NihilCredo 17 May 2010 05:28:42PM *  0 points [-]

If the coin was heads then the probability of event "clone #707 is in a green room" is 1/1000. And since, in this case, the clone in the green room is sure to be an anthropic reasoner, the probability of "clone #707 is an anthropic reasoner in a green room" is still 1/1000.

But you know that you are AR in the exact same way that you know that you are in a green room. If you're taking P(BeingInGreenRoom|CoinIsHead)=1/1000, then you must equally take P(AR)=P(AR|CoinIsHead)=P(AR|BeingInGreenRoom)=1/1000.

and P(#707 is AR | coin was tails and #707 is in a green room) is only 1/999.

Why shouldn't it be 1/1000? The lucky clone who gets to retain AR is picked at random among the entire thousand, not just the ones in the more common type of room.

Comment author: AlephNeil 17 May 2010 06:57:02PM 0 points [-]

Doh! Looks like I was reasoning about something I made up myself rather than Jordan's comment.

Comment author: torekp 03 April 2010 12:27:18AM 0 points [-]

I like this example because it has nice tidy prior probabilities. That's very much lacking in the Doomsday Argument - how do you distribute a prior over a value that has no obvious upper bound? For any finite number of people that will ever live, is there much greater than zero prior probability of that being the number? Even if I can identify something truly special about the reference class "among the first 100 billion people" as opposed to any other mathematically definable group - and thus push down the posterior probabilities of very large numbers of people eventually living - it doesn't seem to push down very far.

Comment author: wedrifid 27 March 2010 04:44:56PM *  11 points [-]

The key point I will remember from reading this post is that the anthropic Doomsday argument can safely be put away in a box labelled 'muddled thinking about consciousness' alongside 'how can you get blue from not-blue?', 'if a tree falls in a forest with nobody there does it make a sound?' and 'why do quantum events collapse when someone observes them?'.

There are situations in which anthropic reasoning can be used but it is a mistake to think that this is because of the ability of a bunch of atoms to perform the class of processing we happen to describe as consciousness.

Comment author: MBlume 28 March 2010 01:08:42AM 4 points [-]

and the rest of us can eat veal and foie gras guilt-free.

I don't think this works.

Obama can use the same argument to decide that, since if he could have been any person, it would be vanishingly likely that he'd be the president of the most powerful nation on earth. Thus, clearly, the rest of us (he would conclude) have no conscious experience, and he had better go ahead and be an egoist, and run the country in whatever way gives him the most personal gain.

I don't want Obama to do this, so I think I had better not do it either.

Comment author: JGWeissman 28 March 2010 01:31:52AM 1 point [-]

Obama can use the same argument to decide that, since if he could have been any person, it would be vanishingly likely that he'd be the president of the most powerful nation on earth. Thus, clearly, the rest of us (he would conclude) have no conscious experience, and he had better go ahead and be an egoist, and run the country in whatever way gives him the most personal gain.

Same argument as here, I don't think 33 bits is enough to support the complexity penalty of the prior.

This is kind of scary though, if I imagine the emperor of a multi-galactic civilization, eventually the population is large enough. It seems unlikely though, even discounting speed of light issues, that a civilization of that size would be united under one single most powerful person.

Comment author: MBlume 28 March 2010 07:36:13AM 4 points [-]

The argument still shouldn't work though. Every one of those bits of evidence that you're the only guy around is counterbalanced by a doubling of the negative consequences if you're wrong.

So yes, maybe Obama should assume he's probably the only guy on earth, but his actions matter so massively much more in the tiny branch where he's really the most powerful man in a world of billions of thinking living people, that he should still be working to optimize for it.

Comment author: ata 27 March 2010 10:14:13PM *  4 points [-]

Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal.

Only in the sense that it's impossible for you to be a rock, or a tree, or an alien, or another person, because you clearly aren't any of those things. All this tells you is that you should be nearly 100% certain that you are you, and that's no great insight.

Comment author: [deleted] 28 March 2010 08:08:19AM 14 points [-]

I'm sorry, but I'm a bit shocked how people on this site can seriously entertain ideas like "why am I me?" or "why do I live in the present?" except as early april's fool jokes. I am of course necessarily me because I call whoever I am me. And I live necessarily in the present because I call the time I live in the present. The question "Why am I not somebody else?" is nonsensical because for almost anybody I am somebody else. I think the confusion stems from treating your own consciousness at the same time as something special and not.

Comment author: Jack 28 March 2010 09:35:55AM 2 points [-]

The question "Why am I not somebody else?" is nonsensical because for almost anybody I am somebody else.

More precisely: "I" refers to some numerically unique entity x. Thus "I is someone else" means x = -x which is an outright contradiction and we shouldn't waste our time asking why contradictions aren't the case.

Comment author: Yvain 28 March 2010 01:21:21PM 13 points [-]

It only sounds nonsensical because of the words in which it's asked. The question raised by anthropic reasoning isn't "why do I live in a time I call the present" (to which, as you say, the answer is linguistic - of course we'd call our time the present) but rather "why do I live in the year 2010?" or, most precisely of all, "Given that I have special access to the subjective experience of one being, why would that be the experience of a being born in the late 20th century, as opposed to some other time?"

That may still sound tautological - after all, if it wasn't the 20th century, it'd be somewhen else and we'd be asking the same question - but in fact it isn't. Consider these two questions:

  • Why am I made out of carbon, as opposed to helium?
  • Why do I live in the 20th century, as opposed to the 30th?

The correct answer to the second is not saying, "Well, if you were made out of helium, you could just ask why you were made out of helium, so it's a dumb question", it's pointing out the special chemical properties of carbon. Anthropic reasoning suggests that we can try doing the same to point out certain special properties of the 20th century.

The big difference is that the first question can be easily rephrased to "why are people made out of carbon and not of helium", but the second can't. But that difference isn't enough to make the second tautological or meaningless.

Comment author: Jack 28 March 2010 02:40:58PM *  8 points [-]

I think maybe some of this was meant for the comment above me.

That said I think the "I" really is the source of some if not all of these confusions and:

The big difference is that the first question can be easily rephrased to "why are people made out of carbon and not of helium", but the second can't. But that difference isn't enough to make the second tautological or meaningless.

I think the difference is exactly enough to make the second one tautological or meaningless. What you have to do is identify some characteristics of "I" and then ask: Why do entities of this type exist in the 20th century, as opposed to the 30th? If you have identified features that distinguish 20th century people from 30th century people you will have asked something interesting and meaningful.

Comment author: Furcas 29 March 2010 04:51:40PM 2 points [-]

If 'you' lived in the 30th century you'd have different memories, at the very least, and thus 'you' would be a different person. That is to say, you wouldn't exist.

On the other hand, if the brain is reasonably substrate-independent, you could be exactly the same person if you were made out of helium.

Comment author: Jack 29 March 2010 07:21:27PM *  1 point [-]

A world different enough from this that you were made out of helium would probably leave you with different memories.

Comment author: Clippy 30 March 2010 05:36:45PM *  3 points [-]

How would you characterise and answer this question:

  • Why do I like to make paperclips, as opposed to other shapes into which I could form matter?
Comment author: Kevin 28 March 2010 09:46:17AM *  1 point [-]

I'm a bit shocked how people on this site can seriously entertain ideas like "why am I me?" or "why do I live in the present?

Out of all of the questions we can ask, "why am I me?" is one of the most interesting, especially if done with the goal of being able to concisely explain it to other people. Your post is confusing to me, because I think "why am I me?" is not a nonsense question but "Why am I not somebody else" is a nonsense question.

Does anyone here think that "why am I me?" is actually a really easy question? What's the answer then, or how do I dissolve the question? I do not claim to understand the mystery of subjective experience. Where I stop understanding is something mysterious connected to the Born probabilities.

Comment author: Jack 28 March 2010 10:18:13AM 3 points [-]

If "Why am I me?" is nonsense it does not follow that all discussions of subjective experience or even anthropic reasoning are nonsense.

Comment author: Kevin 28 March 2010 10:56:17AM *  0 points [-]

Sure. I edited my post to try to make my thoughts on Tordmor's post more clear.

Comment author: [deleted] 28 March 2010 10:12:13PM 5 points [-]

I'm becoming more skeptical of anthropics every day.

Comment author: Oscar_Cunningham 09 April 2010 02:13:01PM 3 points [-]

I think that anthropics is a useless distraction, but until I've worked out why it's a useless distraction it still gets in the way of everything.

Comment author: Strange7 14 January 2011 12:42:19PM 0 points [-]

People don't understand the difference between extreme improbability and actual impossibility. "I observe that I exist, therefore some mysterious 'great filter' will soon wipe out all humanity" is as innumerate a mistake as winning $10^6 with your first-ever lottery ticket and then immediately spending the entire sum on more tickets, because (based on that initial evidence) it's got the biggest, fastest ROI.

We have only what we observe, and what we observe is a green world in a mostly empty universe. Perhaps, in gaining that much, we were very, very lucky; perhaps not. Either way, does it change anything? We have only what we observe. Make the most of it.

Comment author: AllanCrossman 27 March 2010 03:49:41PM 9 points [-]

"why am I me, rather than an animal?" is not obviously sillier than "why am I me, rather than a person from the far future?".

Well, quite. Both are absurd.

Comment author: Mitchell_Porter 28 March 2010 12:51:39AM 4 points [-]

At one time I wondered, why am I not a particle? The anthropic "explanation" is that particles can't be conscious. But that doesn't remove the prior improbability of my existence in this form. Empirically I know I'm conscious, so being a particle (under the usual assumptions) has a posterior probability of zero. But if I think of myself as a random sample from the set of all entities - and why shouldn't I? - then my apriori probability of having been conscious is vanishingly small. (Unless I change my notion of reality rather radically.)

Comment author: komponisto 27 March 2010 03:55:52PM 4 points [-]

Following bogus, I could imagine endorsing a weaker form of the argument: not that it's like nothing to be a bat, but that it's like less to be a bat than to be a human.

In fact, if you've ever wondered why you happen to be the person you are, and not someone else, it may be that the reflectivity you are displaying by asking this question puts you in a more-strongly-anthropically-weighted reference class.

Comment author: Yvain 28 March 2010 01:47:28PM 0 points [-]

Given 10 billion bats , that bats have been around for 50 million years, and bat generations taking let's say 5 years, and assuming that population has been stable for evolutionary history, we have a super rough estimate of something on the order of (10B * (50M/5)) = 100 quadrillion historical bats. I think a lot of anthropic calculations assume there have been 100 billion historical humans, so probability of being a human is 1/1 millionth the probability of being a bat.

I don't see a whole lot of difference between not having subjective experiences and having one one-millionth the subjective experience of a human. Once we expand this to all animals instead of just bats, the animals come out even worse.

Comment author: komponisto 28 March 2010 05:01:26PM 3 points [-]

I'm not sure it follows that a bat has one one-millionth the subjective experience of a human. The problem is that you can't necessarily add a bunch of bat-experiences together to get something equivalent to a human experience; in fact, it seems to me that this sort of additivity only holds when the experiences are coherently connected to each other. (If someone hooked up a million bat-brains into a giant network, then it might make sense to ask "Why am I a human, rather than a million bats"?)

So it may be, for instance, that each bat has 10% the subjective experience of a human, but that that extra 90% makes it millions of times more probable that the experiencer will be pondering this question.

Comment author: Sticky 31 March 2010 02:20:48PM 1 point [-]

Is there a difference between having no subjective experience and having one-millionth the subjective experience of a Tra'bilfin, which are advanced aliens with artificially augmented brains capable of a million times the processing of a current human?

Comment author: Jack 28 March 2010 02:43:22PM 0 points [-]

You don't have any issues quantifying over fractions of subjective experience? I haven't begun to have a clear idea what that even means.

Comment author: UnholySmoke 29 April 2010 02:37:33PM 2 points [-]

The phrase "for me to be an animal" may sound nonsensical, but "why am I me, rather than an animal?" is not obviously sillier than "why am I me, rather than a person from the far future?".

Agreed - they are both equally silly. The only answer I can think of is 'How do you know you are not?" If you had, in fact, been turned into an animal, and an animal into you, what differences would you expect to see in the world?

Comment author: Strange7 14 January 2011 11:59:53AM 3 points [-]

When I looked down, I'd see fur or something instead of my manly abs.

Comment author: DanielLC 09 April 2010 04:42:20AM 2 points [-]

The fact that you are human is evidence that only humans are conscious, but it's far from proof. If you have no a priori reason to believe that only humans are conscious, that means it's just as likely that it's only humans as only bats. If the a priori probability of all animals being conscious is only the same as the probability that it's just a given species (I'd say it's much, much larger), and it's impossible for it to just be two species etc., then a posteriori, there would still be a 50:50 chance that all animals are conscious.

Of course, there is an a priori reason to believe humans are conscious. We are more intelligent than the vast majority of animals. We have bigger brains. That said, I still find it very unlikely that humans are sentient but dolphins aren't. Their brains are bigger, after all.

Comment author: wnoise 09 April 2010 01:48:39PM 1 point [-]

(Psst: almost all animals are sentient (have senses), you might be thinking of sapient (conscious, having thoughts)).

Comment author: DanielLC 14 May 2010 10:53:03PM 5 points [-]

I thought sentient was having qualia and sapient was intelligent thought.

I just checked a few dictionaries (Wikipedia, Dict.org etc.). It looks like my usage is the more common one.

Comment author: Blueberry 14 May 2010 11:01:11PM 0 points [-]

Qualia is a confused concept and doesn't really exist as such, so that may not be the best way to phrase it.

Comment author: Mitchell_Porter 15 May 2010 03:27:14AM 3 points [-]

"Qualia" is effectively a name for all those properties which constitute your experience of the world, but which do not exist in the current ontology of natural science (thus we have the spectacle of people on this site needing to talk about "how it feels" to be a brain or a computer program, an additional property instinctively tacked on to the physical description precisely to make up for this lack).

This is a problem that has been building in scientific culture for centuries, ever since a distinction between primary and secondary properties was introduced. Mathematical physics raised the description and analysis of the "primary" properties - space, quantity, causality - to a high art, while the "secondary" properties - all of sensation, to begin with, apart from the bare geometric form of things - were put to one side. And there have always been a few people so enraptured by the power of physics and related disciplines that they were prepared to simply deny the existence of the ontological remainder (just as there have been "irrationalists" who were really engaged in affirming the reality of what was being denied).

We are now at the stage of figuring out rather detailed correlations between parts and states of the brain, described in material terms, and aspects of conscious experience, as experienced and reported "subjectively" or "in the first person". But a correlation is not yet an identity (and the verifiable correlations are still mostly of the form "X has something to do with Y"). Mostly people are being property dualists without realizing it: they believe their experiences are real, they believe those experiences are identical with brain states, but out of sheer habit they haven't noticed that the two sides of the identity are actually quite different ontologically.

Dennett belongs to that minority of materialists, more logically consistent but also more in denial of reality, who really are trying to deny the existence of the secondary properties, now known as qualia. It's possible to read him otherwise, because he does talk about his own experience; but if you look at his checklist of properties to deny, you can see he's a sort of neo-behaviorist, focused on verbal behavior. Indeed, the only thing neo about his behaviorism is that he has a physical model of how this behavior is caused (connectionist neural networks). But he is careful to say quite explicitly that there is no "Cartesian theater", no phenomenal color, no inner life, just people talking about these things.

I cannot tell if you are truly in Dennett's camp, or if you're just rejecting the view that there's something especially problematic about explaining sensations. A lot of people who talk about qualia are trying to emphasize that a description of human beings in terms of causal interactions between pieces of matter is leaving something out. But the things being left out are not in any way elusive or ineffable.

Science seems to be telling us that your whole life, everything you have ever experienced, is nothing but changes of state occurring in a few trillion neurons which have been sitting inside the same small dark space (your skull) for a few decades. Now if that's the case, I may not be able to write an equation describing the dynamics, but I do know what that is physically. It's a large number of electrons and quarks suspended in space by electromagnetic fields. If we are to unconditionally accept this as a description of what our lives and experiences really are, then we have to be able to identify everything - everything - we have ever thought, known, or done, the whole of our subjective realities, as a process composed of nothing but changes of states of particles all occurring within a few cubic centimeters of space. And I have no hesitation at all in saying that this is impossible, at least if the basic ingredients, those particles and fields, are understood as we currently conceive them to be.

Quite apart from the peculiar difficulty involved in identifying complex subjective states like "going diving in the Caribbean on your 25th birthday" with the electrical state of a captive neuronal porridge, the basic raw ingredients of subjective experience, like color qualia, simply aren't there in an arrangement of pointlike objects in space. This is why materialists who aren't eliminativists like Dennett are instead dualists, whether they realize it or not - because they simultaneously assert the existence of both the world of atoms in space and the world of subjective experience. These two worlds may be correlated, that is being demonstrated every day by neuroscience, but they simply cannot be identified under the physical ontology we have.

In my opinion the future lies with a new monism. But "physics" will have to be reconceptualized, if that world of subjective experience really is going to be found somewhere inside the skull, because as things stand there is nothing like it in there. I would also say that doing this is going to require a leap as big as anything in human intellectual and cultural history. It won't just be a matter of identifying the "neural correlate of consciousness". Someone is going to have to go right back to the epistemic beginning, before the distinction between primary and secondary properties, and rethink the whole of natural science from Galileo through to molecular neuroscience, while keeping the secondary properties in view. You can always reduce science to subjectivity, if you're prepared to let go of your models and remember that everything that has ever happened to you has occurred within your own subjective experience, so that's the easy part. What we're aiming for is far more difficult, namely, an objective world-picture which really does contain subjective experience and is true to its nature while also encompassing everything else. Of course, all those people who are out there trying to "naturalize subjective experience" or "naturalize phenomenology" are trying to do this, but without exception they presuppose the current "naturalistic" ontology, and yet somehow that is where the change and the progress has to occur.

Comment author: pjeby 15 May 2010 04:24:51AM 3 points [-]

Quite apart from the peculiar difficulty involved in identifying complex subjective states like "going diving in the Caribbean on your 25th birthday" with the electrical state of a captive neuronal porridge, the basic raw ingredients of subjective experience, like color qualia, simply aren't there in an arrangement of pointlike objects in space.

Suppose I write a computer program (such as Second Life or World of Warcraft) that simulates the properties of an imaginary reality. Have I now created new "subjective secondary properties"? After all, in the real world, objects do not have owners and copyability, nor levels of mana or hit points. Is this "duality", then?

What about a book that describes an imaginary world? Is it duality because there are only words on the page, and these have no physical correlate to the things described?

The reasoning that you're using is an application of the mind projection fallacy. Human brains have built-in pattern recognition for seeing things as "minds", and having volition -- and this notion is itself an example of an imaginary property projected onto reality. The projection doesn't make the projected quality exist in outside reality, it merely exists in the computational model physically represented in the mind that makes the projection

tl;dr version: imaginary attributions in a model do not create dualtiy, or else computer programs have qualia equal to those of humans. Since no mysterious duality is required to create computer programs, we need not hypothesize that such is to create human subjective experience.

Comment author: Mitchell_Porter 16 May 2010 06:31:38AM 1 point [-]

Human brains have built-in pattern recognition for seeing things as "minds", and having volition -- and this notion is itself an example of an imaginary property projected onto reality. The projection doesn't make the projected quality exist in outside reality, it merely exists in the computational model physically represented in the mind that makes the projection

(My emphases.)

You seem to be contradicting yourself there. The mind only exists in the mind?

Comment author: pjeby 16 May 2010 05:36:43PM 4 points [-]

The mind only exists in the mind?

The intuitive notion of "mind" exists only in the physical manifestation of the mind.

Or to put it (perhaps) more clearly: the only reason we think dualism exists is because our (non-dual) brains tell us so. Like beauty, it's in the eye of the beholder.

Our judgment of whether something is intelligent or sentient is based on an opaque weighing of various sensory criteria, that tell us whether something is likely to have intentions of its own. We start out as children thinking that almost everything has this intentional quality, and gradually learn the things that don't.

It's as if brains have a built-in (at or near birth) "mind detector" circuit that triggers for some things, and not others, and which can be trained to cease seeing certain things as minds.

What it doesn't do, is ever fire for something whose motions and innards are fully understood as mechanical - so it doesn't matter how sophisticated AI ever gets, there will still be people who will insist it's neither conscious nor intelligent, simply because their built-in "mind detector" doesn't fire when they look at it.

And that's what people are doing when they claim special status for consciousness and qualia: elevating their genetically-biased intuition into the realm of physical law, not unlike people who insist there must be a soul that lives after death... because their "mind detector" refuses to cease firing when someone dies.

In short, this intuitive notion of mind gets in the way of developing actual artificial intelligence, and it leads to enormous wastes of time in discussions of dualism. Without the mind detector -- or if the operation of our mind detectors were fully transparent to the rest of our mental processes -- nobody would waste much time on the idea that there's anything non-physical. We'd only get as far as realizing that if there were non-physical things, we'd have no way to know about them.

However, since we do have an opaque mind-detector, that's capable of firing for the wind and the rain and for memories of dead people as easily as it does for live animals and people in front of us, we can get the feeling that we are having physical experiences of the non-physical... when that's a blatantly obvious contradiction in terms.

It's only by elevating your feelings and intuitions to the level of fact (i.e. abandoning science), that you can continue to insist that non-physical things exist in the physical world. It's pointing to reality and saying, I feel X when I look at it, therefore it is X.

(A bit like the religious fundamentalists who say that they feel icky when they see gays, therefore homosexuality is disgusting.)

Comment author: RobinZ 16 May 2010 05:47:01PM 1 point [-]

(A bit like the religious fundamentalists who say that they feel icky when they see gays, therefore homosexuality is disgusting.)

I would have said, "A bit like philosophers of free will who say that they feel like they could have done something else, and therefore determinism must be false". (:

Comment author: Blueberry 15 May 2010 05:26:26AM 2 points [-]

I upvoted you back to 0 because your comment was thoughtful and well-written, even though I disagree.

Yes, I'm in Dennett's camp. Aside from what other commenters have said, think about it like this:

I have a novel here. It's made of the letters A-Z as well as punctuation, arranged in a complicated pattern. But, somehow, the novel also talks about a plot and characters and a setting and so forth, even though all there is to the novel is letters and punctuation. The plot and characters don't have some magical separate state of existence: they exist because they're built out of the letters.

Same with conscious experience. Right now I'm eating goat cheese and crackers. This experience arises out of the neurons in my brain, and it's intimately tied up with them and the patterns they make. You can't separate it from my past experience and associations and memories (which is Dennett's point about qualia). Of course the experience exists: it's just built out of and associated with a complex pattern of neuron firings in my brain. The experience is not the same as the series of neurons: that would be a category error, just like a character in a book is not the same as the series of letters that make up his description. No property dualism needed. Of course it's difficult to explain this association, because we don't know enough about brain chemistry.

Comment author: AlephNeil 15 May 2010 05:51:35AM 2 points [-]

I upvoted you back to 0 because your comment was thoughtful and well-written, even though I disagree.

Me too.

Yes, I'm in Dennett's camp. Aside from what other commenters have said, think about it like this:

Me too.

I think it's a good illustration, but I can give you 'the standard reply' from the anti-materialist: As a physical object, the novel is just a hunk of matter with funny shaped ink blotches on it. The 'plot' and 'characters' you speak of have a mental character to them: they don't exist outside of some mind apprehending the novel, a mind which actively 'constructs' these things rather than passively 'finding them' somewhere in the matter of the book.

So book --> plot is not after all an analogy that helps us understand how a mind can reduce to a pattern of physical matter, because "plot" already presupposes the mind, so any "reduction" would presuppose that the mind is itself reducible.

Yeah, I know this is all wrong - but I've learned to make myself "flip" between a materialist and anti-materialist view.

Comment author: Blueberry 15 May 2010 06:00:42AM 2 points [-]

Hmm. Maybe a better analogy is three stones in a field making a triangle. The triangle exists and is formed by the stones, but this doesn't require dualism, just an understanding that relationships and structures exist and are built out of smaller parts. (I know, that's not exact either.)

Comment author: Mitchell_Porter 16 May 2010 09:20:19AM 0 points [-]

Earlier you wrote

Of course it's difficult to explain this association, because we don't know enough about brain chemistry.

The ontological ingredients, and the ways of combining them, which physics gives you are quite limited. You can make shapes (like your triangle), you can count objects, you can consider their motions and other changes of state, you can average quantitative properties, you can consider causal dependence and counterfactual situations. There might be a few other things you can do. But if you are going to have a mind-brain identity theory, and not property dualism, then something built solely using methods like the ones I just listed has to be the experience. It can't just be "associated with" the experience - that would be dualism.

Color is usually mentioned at this point, because it is pretty obvious that no amount of piling up particles, averaging their properties, and engaging in causal and counterfactual analysis, is going to give you redness where there was none, in the simple way that putting three stones in a field really does give you a triangle. If someone proposes that the experience of a certain shade of red is some complicated but purely physical predicate, object, or condition, then from the perspective of orthodox physical ontology, they are proposing a form of strong emergence. (Weak emergence is like the triangle.) And strong emergence is property dualism - it introduces new ontological ingredients.

But although color is the standard counterargument - because of its vividness - any sensation, any thought, anything involving a self, anything like the "experience of an object", is just as much unlike anything that can be made from physics in a weakly emergent way. I challenge you to find a single aspect of your experience which you can unproblematically identify with (and not just associate with) some imagined neurochemical correlate. In every case, you will be taking some subjectively manifest reality, and then saying to yourself, "that is really just neurons doing something"; and in every case, physics alone gives you absolutely no reason to think that neurons doing that has any subjective side to it.

If you don't want to be a dualist, you are going to have to take that subjectively manifest reality, admit that it exists somewhere in exactly that form, and somehow rebuild physics around it. But that is really hard to do.

Comment author: Strange7 14 January 2011 12:26:13PM 0 points [-]

Three rocks in a field aren't a triangle until there's a brain with a concept of 'triangle' that identifies them as such. Photons of a particular wavelength aren't red until there's a brain with a concept of 'red' that identifies them as such. A creature isn't conscious until there's a brain with a concept of 'consciousness' that identifies it as such.

Third one's tricky because of the self-reference, but that doesn't make it an exception to the general rule. Concepts are predictive models, a model can't make predictions unless it's running on a computer, brains are the one kind of computer that can be mass produced by unskilled labor. Qualia, to the extent that they can be coherently defined at all, are a matter of software. Software can be translated between hardware platforms, but cannot exist in any useful form in the absence of hardware.

And, for the record, the math necessary to fully define a rock is a hell of a lot more complicated than "1+1." Don't dismiss it until you've properly studied it.

Comment author: AlephNeil 15 May 2010 06:14:54AM 1 point [-]

Or three quarks making a proton.

Comment author: TheOtherDave 07 January 2011 06:09:15PM 3 points [-]

Suppose on Tuesday I perceive object O as red.

For labeling convenience, I'm going to start referring to my subjective experience of that perception as <red>. In other words, on Tuesday I experience O as <red>.

If I've understood you, you claim the <red> is due in part to color qualia in some way associated with O, which are distinct from the set of things happening inside my skull.

So, OK, assuming that, some questions.

I assume we agree that if I suddenly become color-blind, I might suddenly stop experiencing <red>. Do you assert that in that case the <red>-causing qualia continue to exist, I just stop experiencing them? (I would say something analogous about photons and perception, for example, if I suddenly lose my eyes.) Or do you assert that they stop existing? Or something else?

Either way: is that assertion something someone has confirmed in some way, or is it a purely theoretical prediction?

I assume we agree that if I suddenly manifest synesthesia -- say, due to a stroke -- I might also start experiencing a honking car horn as <red>. I assume you would therefore say that there must be <red>-causing qualia present, since my brain is unable to construct <red> on its own. Do you assert that the <red>-causing qualia were always present, and I've only just become able to perceive them? Or that they became present when I had the stroke, but not previously? Or something else?

Again: is that assertion something confirmed or theoretical?

Comment author: Mitchell_Porter 08 January 2011 03:34:45AM 2 points [-]

If I've understood you, you claim the <red> is due in part to color qualia in some way associated with O, which are distinct from the set of things happening inside my skull.

No. I think that in reality, <red> is in the head. But our current physical ontology contains no such entity. That is why I say that if you accept our current physical ontology, you're either an eliminativist or a dualist.

Comment author: TheOtherDave 08 January 2011 07:50:24AM 0 points [-]

I'm not in the least bit interested in the labels. But yes, if we're agreed that <red> is constructed by my brain, rather than being a property of my environment, then I don't understand what grounds you have for believing that <red> isn't explicable by entities in our current physical ontology.

Comment author: Mitchell_Porter 08 January 2011 09:19:29AM 3 points [-]

Just imagine if you were having a discussion with someone who said that the world is made of numbers. And you picked up a rock and said, so, this rock is made of numbers? And they said, sure. And you said, that's absurd. How could a rock be equal to 1+1, for example? They're completely different kinds of things. And they went off on a riff about how science has shown that all is number, and whenever you tried to point out the non-numerical aspects of reality, they'd just subsume that back into the all-is-number reductionism, and they'd stubbornly insist that, even if the rock was not equal to 1+1, it might be equal to some other numbers, and besides, what other sort of things could there be, besides numbers?

For me, the idea that <red> is identical to some arrangement of particles in space is just like saying that 1+1 is a rock. The gulf between the nature of the allegedly identical entities is so great that the problem with the assertion ought to be obvious. In a sprinkling of point objects throughout space, where is the color? It's really that simple. It's just not there. It's not intrinsically there, anyway. You might propose that redness is a property of certain special configurations, but when you say that, you've embarked upon a form of dualism, property dualism. It's a dualism because on the one side, you have properties which are intrinsic to a geometrically defined situation, like distances and angles and shapes; and on the other side, you have properties which are logically independent of the geometric facts and have to be posited separately. For example, the existence of color experiences, or indeed any kind of experiences, in a brain.

In other words, the onus is on you to explain just what you think the connection is between arrangements of particles in space (e.g. a brain), and experiences of color. I have my own answer, but I want to hear yours first.

Comment author: TheOtherDave 08 January 2011 10:24:54AM 2 points [-]

You won't find my answer interesting, but since you asked: I think experiences of color are among the states that particles in space can get into, just as the impulse to blink is a state particles in space can get into, just as a predisposition to generate meaningful English but not German sentences is a state that particles in space can get into, just as an appreciation for 17th-century Romanian literature is a state that particles in space can get into, just as a contagious head cold is a state that particles in space can get into. (Which is not to say that all of those are the same kinds of states.)

We can certainly populate our ontologies with additional entities related to those various things if we wish... color qualia and motor-impulse qualia and English qualia and German qualia and 17th-century Romanian literary qualia and contagious head cold qualia and so forth. I have no problem with that in and of itself, if positing these entities is useful for something.

But before I choose to do so, I want to understand what use those entities have to offer me. Populating my ontology with useless entities is silly.

I understand that this hesitation seems to you absurd, because you believe it ought to seem obvious to me that arrangements of matter simply aren't the kind of thing that can be an experience of color, just like it should seem obvious that numbers aren't the kind of thing that can be a rock, just as it seems obvious to Searle that formal rules aren't the kind of thing that can be an understanding of Chinese, just as it seemed obvious to generations of thinkers that arrangements of matter aren't the kind of thing that can be an infectious living cell.

These things aren't, in fact, obvious to me. If you have reasons for believing any of them other than their obviousness, I might find those reasons compelling, but repeated assertions of their obviousness are not.

Comment author: Mass_Driver 08 January 2011 09:27:21AM 0 points [-]

I find this argument irresistably compelling, and would appreciate a post or a private message letting me know what your answer is. I don't have one; it's all I can do here to notice that I am confused.

Comment author: AlephNeil 15 May 2010 04:07:40AM *  3 points [-]

I think you need to be taken outside and shot...

...

...j/k.

It's just that over recent years I've spent quite a long time arguing with people educated principally in philosophy, who hate Dennett and think his version of materialism is absurd (or at least that it's manifestly wrong), and think it's absolutely essential to go around saying things like 'all we know about are correlations between body and mind'.

It's sort-of interesting/refreshing for me to arrive here, with a bunch of people who are (I assume) educated principally in computer science (with perhaps a few mathies and physicists), who are almost unanimously Dennett fans, think that functionalism is just blindingly obvious, that 'zombies' are blindingly obviously impossible, that it's blindingly obvious that the 'Systems Reply' is correct, that anything we build capable of passing the (full) Turing Test would have to be conscious etc.

The ones who don't 'get it' - that at the core of Dennett's view there's the difficult-to-swallow idea that there isn't a 'fact of the matter' as to whether a being is conscious and if so what it's conscious of - can at least fall back on a Greg Egan-style view of consciousness which is identical insofar as it agrees that the issues above are 'blindingly obvious'. (That's the other thing: the people here have actually read Greg Egan - woohoo.)

I can see you have a more in common with the philosopher-types than the locals. And actually, in your interpretation of Dennett I think there's a mistake - one I've seen elsewhere:

You think that in abolishing the 'Cartesian theater' he is ipso facto abolishing phenomenal awareness, but this simply doesn't follow. What he's abolishing is the idea that all of the 'bits' of a person's awareness are present 'together' in a single sharply-defined 'moment', such that there are well-defined answers to questions like "am I seeing a moving dot or a static one?" which would resolve the "Orwellian/Stalinesque" dilemma.

Even after the Cartesian theater is abolished, you can still be a dualist as long as you're prepared to give ground on things like 'the unity of consciousness', and admit that the various parts of the mindscape are slightly removed from each other - not as far removed as the mind of a different person altogether, or even as far as the two hemiminds of a split-brain patient, but certainly not bundled together in a brilliant 'point' of 'inner light'.

Comment author: Mitchell_Porter 16 May 2010 09:41:39AM 2 points [-]

I think you need to be taken outside and shot...

I'd just come back as a zombie.

the difficult-to-swallow idea that there isn't a 'fact of the matter' as to whether a being is conscious and if so what it's conscious of

That sums it up well. Next up, let's consider other startling possibilities, such as: there isn't a fact of the matter as to whether you're reading this sentence, there isn't a fact of the matter as to whether this planet exists, there isn't a fact of the matter as to whether there is a fact of the matter as to whether a being is conscious...

Comment author: AlephNeil 16 May 2010 10:38:14AM *  4 points [-]

Yeah but come on... you always-a-fact-of-the-matter-ists have some startling things to think about too, like The Exact Moment When You First Became Conscious, and the Infinitely Precise Line one can draw across the phylogenetic tree demarcating species whose members are (or may be) conscious and those which never are.

(Afterthought: Or are you some kind of panpsychist? Then your startling possibilities incude the minds of rocks...)

Comment author: Mitchell_Porter 16 May 2010 11:10:12AM 0 points [-]

you always-a-fact-of-the-matter-ists have some startling things to think about too, like The Exact Moment When You First Became Conscious, and the Infinitely Precise Line one can draw across the phylogenetic tree demarcating species whose members are (or may be) conscious and those which never are

See, it's not so hard! You just have to take the idea seriously, and stick with it. You might even have a talent for this. And here I was thinking that my labor here was in vain.

Comment author: Blueberry 15 May 2010 05:36:21AM 0 points [-]

that anything we build capable of passing the (full) Turing Test would have to be conscious

I believe Eliezer doesn't agree with that last one, and has talked about building an AI who isn't conscious.

Also, consider the following hypothetical: I get really drunk and/or take Ambien and black out at 2 am. I have no conscious experience or memory of the time between 2 am and 3 am, but during that time you have a (loud and drunken) conversation with me. Or maybe in my drunken state I sit at my computer and manage to instant message without being conscious of it, and the person at the other end is convinced I'm human and not a computer program. Counterexample?

Comment author: AlephNeil 15 May 2010 06:31:41AM 1 point [-]

Well, I think we can all agree that it's possible for a non-conscious person (or program or whatever) to be mistaken for a conscious being.

However, there are several objections I can make to this scenario being considered a counterexample:

(1) How do you know you're not conscious? Just because you don't remember it the next day doesn't mean you don't have any awareness at the time.

(2) In the Turing test the judge is supposed to be 'on the look-out' for which of its two subjects seems less able to respond adequately to their questions. And one of the subjects is presumed to be a healthy, sober human. So unless you think the judge would be unable to distinguish a drunken, unconscious conversation from a normal, sober one, you would presumably fail the Turing test.

Comment author: Jack 15 May 2010 11:09:17AM 0 points [-]

These two worlds may be correlated, that is being demonstrated every day by neuroscience, but they simply cannot be identified under the physical ontology we have.

What exactly do you take the purpose of an ontology to be? If you have a scientific theory whose predictions hit the limit of accuracy for predicted experience why do you need anything in your ontology beyond the bound variables of the theory?

Comment author: Mitchell_Porter 16 May 2010 09:32:10AM 1 point [-]

An ontology is a theory about what's there. The attributes of experience itself, like color, meaning, and even time, have been swept under a carpet variously labeled "mind", "consciousness", or "appearance", while the interior decorators from Hard Science Inc. (formerly trading as the Natural Philosophy Company) did their work. We have lots of streamlined futuristic fittings now, some of them very elegant. But they didn't get rid of the big lump under the carpet. The most they can do is hide it from view.

Comment author: Jack 16 May 2010 12:15:47PM 0 points [-]

An ontology is a theory about what's there.

We don't have access to "what is there". What we have are sensory experiences. Lots of them! Something is generating those experiences and we would like to know what we will experience in the future. So we guess at the interior structure of the experience generator and build models that predict for us what our future experiences will be. When our experiences differ from expected we revise the model (i.e. our ontology). This includes modeling the thing that we are which improves our predictions of our own experiences and our experiences of what other humans say are their experiences. One thing humans report is the experience is seeing color. So we need to explain that. One thing humans report is the experience is self-awareness so we have to explain that etc. You seem to want to reify the sensory experiences themselves just because they look different in our model than in our experience. But the model isn't supposed to look like our experience it is supposed to predict it. You're making a category error. Presumably you know this and think the problem is the categories. But you need to motivate your rejection of the categories. All I want are predictions and I've been getting them, so why should I reject this model?

The attributes of experience itself, like color, meaning, and even time, have been swept under a carpet variously labeled "mind", "consciousness", or "appearance",

But lots of scientists study these things! Last semester I learned all about auditory and visual perception. There is a lot we don't know which is why they're still working on it.

Comment author: Mitchell_Porter 16 May 2010 12:35:27PM 0 points [-]

We don't have access to "what is there". What we have are sensory experiences.

So we know that whatever is there must include those sensory experiences. They themselves are part of reality.

But the model isn't supposed to look like our experience it is supposed to predict it.

Most models of reality are partial models that implicitly presuppose some untheorized notion of experience in the model-user. Medicine and engineering aren't especially focused on the fact that doctors and engineers encounter the world, like everyone else, through the medium of conscious experience.

But there are two types of explanatory enterprise where conscious experience does become explicitly relevant. One is any theory of everything. The other is any science which does take experience as its subject matter. In the latter case, scientists will explicitly theorize about the nature of experience and its relationship to other things. In the former case, a theory of everything must take a stand on everything, including consciousness, even if only to say "it's made of atoms, like everything else".

So some part of these models is supposed to look like experience. However, as I have been saying elsewhere, nothing in physical ontology looks like an experience; and the sciences of consciousness so far just construct correlations between "physics" (i.e. matter) and experience. But they must eventually address the question of what an experience is.

Comment author: PhilGoetz 15 May 2010 03:46:37AM 0 points [-]

Nice essay! I'm not yet won over by the suggestion in your final paragraph, but it's intriguing.

Comment author: rhollerith_dot_com 15 May 2010 06:31:47AM 3 points [-]

Phil writes, "Nice essay!"

Is there something in Mitchell's essay (comment) that Mitchell has not already said on this site 30 times or did you just like the way he phrased it this time?

Comment author: DaveInNYC 27 March 2010 08:06:57PM *  4 points [-]

Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be.

I do not really think you need an anthropic argument to prove that "you" couldn't be an animal; it is more a matter of definition, i.e. by definition you are not an animal. For example, there is no anthropic reason that "I" couldn't have been raised in Alabama, but what would it even mean to say that I could have been raised in Alabama? That somebody with the same exact genes and parents was raised in Alabama? In that case, it is the same as saying I have an identical twin that was raised there. The fact of the matter is that when I say "I", I am referring to someone with all of the same genes and experiences I have. To say that "I" could have been some other human is nonsensical; to say that "I" could have been a bat is even more so.

Comment author: Peterdjones 16 April 2011 07:27:58PM 2 points [-]

You can't be a toaster, because toasters don't have any awareness at all. As a philosophical ponderer, you likewise can't be an animal lower than H. Sap. If you were, you wouldn't be able to reflect on it.

Comment author: JGWeissman 27 March 2010 08:19:35PM 2 points [-]

The anthropic principle seems to imply that our subjective experiences take place in amazingly common ancestor simulations that don't simulate animals in sufficient detail to give them subjective experience. That I find myself experiencing being a human rather than being a bat, even though bats are in principle capable of subjective experience, is because there are vastly more detailed simulations of humans than of bats.

Comment author: PhilGoetz 27 March 2010 09:26:17PM -1 points [-]

You mean, you believe the anthropic principle is justified only if you assume that most people exist in simulations?

Comment author: Kutta 27 March 2010 06:49:30PM *  2 points [-]

Bats, with sensory systems so completely different from those of humans, must have exotic bat qualia that we could never imagine. (...) ...we still have no idea what it's like to feel a subjective echolocation quale.

(Excuse me for being off topic)

Reductionism is true; if we really know everything about a bat brain, bat quale would be included in the package. Imagine a posthuman that is able to model a bat's brain and sensory modalities on a neural level, in its own mind. There is no way it'd find anything missing about the bat; there is no way it'd complain about persistently mysterious bat quale. It's a fact that current humans are very bad at modeling any minds, including their own. Thus, human-level neuroscientists researching the bat's brain are a bit like the human operator in Searle's Chinese Room; they have access to a lot of abstract information but they're unable to actually hold a neural model of the bat in their minds and simulate firings.

In short, I think that in this case it's more reasonable to point to insufficiencies in brainpower before we start considering fundamental epistemological problems.

Comment author: wedrifid 27 March 2010 07:18:27PM *  3 points [-]

It's a fact that current humans are very bad at modeling any minds, including their own.

"Very bad" compared to what? We are brilliant at modelling minds relative to our ability for abstract reasoning, mathematics and, say, repeating a list of 8 items we were just told in reverse order.

Comment author: Kutta 27 March 2010 09:32:59PM *  3 points [-]

Trying to imagine neurons and simulating firings by doing mental arithmetic still seems to be far-fetched, which is the kind of modeling I meant.

Comment author: bogus 27 March 2010 03:06:57PM 1 point [-]

Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal.

You assume that you have equal probability of being any conscious being. The internal subjective experience of humans stands out in its complexity; perhaps more complex subjective experiences have higher weight for some reason.

Comment author: neq1 17 May 2010 05:48:31PM 1 point [-]

Anthropic reasoning is what leads people to believe in miracles. Rare events have a high probability of occurring if the number of observations is large enough. But whoever that rare event happens to will feel like it couldn't have just happened by chance, because the odds of it happening to them was so large.

If you wait until the event occurs, and then start treating it as a random event from a single trial, forming your hypothesis after seeing the data, you'll make inferential errors.

Imagine that there are balls in an urn, labeled with numbers 1, 2,...,n. Suppose we don't know n. A ball is selected. We look at it. We see that it's number x.

non-anthropic reasoning: all numbers between 1 and n were equally likely. I was guaranteed to observe some number, and the probability that it was close to n was the same as the probability that it was far from n. So all I know is that n is greater than or equal to x.

anthropic reasoning: A number as small as x is much less likely if n is large. Therefore, hypotheses with n close to x are more likely than hypotheses where n is much larger than x.

Comment author: Cyan 17 May 2010 09:13:25PM 3 points [-]

What you have labeled anthropic reasoning is actually straight-up Bayesian reasoning. Wikipedia has an article on the problem, but only discusses the Bayesian approach briefly and with no depth. Jaynes also talks about it early in PT:LOS. In any event, to see the logic of the math, just write down the likelihood function and any reasonable prior.

Comment author: CarlShulman 17 May 2010 06:37:27PM 0 points [-]

I suggest reading Radford Neal.

Comment author: neq1 17 May 2010 06:49:15PM 0 points [-]

Yes, I've read that paper, and disagree with much of it. Perhaps I'll take the time to explain my reasoning sometime soon

Comment author: timtyler 16 May 2010 07:46:44AM 0 points [-]

Yvain, you are an animal.

Comment author: bgrah449 27 March 2010 02:55:26PM 0 points [-]

This argument would have to apply to people who were born completely blind, or completely deaf. Just imagine that all humans are echolocation-deaf/blind.

Comment author: PhilGoetz 28 March 2010 12:46:27AM *  1 point [-]

[Edited, because it was wrong.]

The doomsday argument is,

O(X) = random human me observes some condition already satisfied for X humans

pt(X) = P(there will be X humans total over the course of time)

pt(2X | O(X|2)) / pt(2X) < pt(X | O(X/2)) / pt(X)

This is true if your observation O(X) is, "X people lived before I was born", or, "There are X other people alive in my lifetime".

But if your observation O(X) is "I am the Xth human", then you get

pt(2X | O(X|2)) / pt(2X) = pt(X | O(X/2)) / pt(X)

and the Doomsday argument fails.

So which definition of O(X) is the right observation to use?

Comment author: Psychohistorian 27 March 2010 06:20:57PM *  1 point [-]

The anthropic principle is contingent on no additional information. For example, if sentient life exists elsewhere in the universe, your odds of being a human are vanishingly small. This would suggest sentient life does not exist elsewhere in the universe. However, given that there appears to be nothing so special about earth that it wouldn't reoccur many times among trillions and trillions of stars, we can still conclude that sentient life does likely exist elsewhere in the universe.

Similarly, in this context, the fact that animals have brains that are relatively similar to ours itself gives you evidence with which to refine the anthropic argument. As you said, that hard line between experience-having and not-experience having would be weird. Thus, evidence from the observed universe trumps, or at least significantly adjusts, the anthropic argument.

It seems to take very tiny pieces of evidence to destroy a lot of anthropic reasoning, which is why, as much as I'd enjoy me some fillet-'o-chimp, I don't generally trust anthropic reasoning as a stopping point; we can often improve on it with available information.

Comment author: PhilGoetz 27 March 2010 09:29:48PM *  4 points [-]

For example, if sentient life exists elsewhere in the universe, your odds of being a human are vanishingly small. This would suggest sentient life does not exist elsewhere in the universe.

That's not how the anthropic principle works.

The anthropic principle lets you compute the posterior probability of some value V of the world, given an observable W. The observable can be the number of humans who have lived so far, and the value V can be the number of humans who will ever live. The probability of a V where 100W < V is smaller than the probability of a V only a few times larger than W.

It's unclear if you get to count transhumans and AIs in V, which is the same problem Yvain is raising here about whether to include bats and ants in the distribution.

You can't conclude that there aren't other planets with life because you ended up here, because the probability of different values of V doesn't depend on the observable W. There's no obvious reason why P(there are 9999 other planets with life | I'm on this planet here with life) / P(there are 9999 other planets with life) would be different than P(there are 0 other planets with life | I'm on this planet with life) / P(there are 0 other planets with life).

(I divided by the priors to show that the anthropic principle takes effect only in the conditional probability; having a different prior probability is not an anthropic effect.)

Disclaimer: I'm a little drunk.

I'm troubled now that this formulation doesn't seem to work, because it relies on saying "P(fraction of all humans who have lived so far is < X)". It doesn't work if you replace the "<" with an "=". But the observable has an "=".

BTW, outside transhumanist circles, the anthropic principle is usually used to justify having a universe fine-tuned for life, not to figure out where you stand in time, or whether life will go extinct.

Comment author: PlatypusNinja 31 March 2010 06:49:09PM 3 points [-]

The anthropic principle lets you compute the posterior probability of some value V of the world, given an observable W. The observable can be the number of humans who have lived so far, and the value V can be the number of humans who will ever live. The probability of a V where 100W < V is smaller than the probability of a V only a few times larger than W.

This argument could have been made by any intelligent being, at any point in history, and up to 1500AD or so we have strong evidence that it was wrong every time. If this is the main use of the anthropic argument, then I think we have to conclude that the anthropic argument is wrong and useless.

I would be interested in hearing examples of applications of the anthropic argument which are not vulnerable to the "depending on your reference class you get results that are either completely bogus or, in the best case, unverifiable" counterargument.

(I don't mean to pick on you specifically; lots of commentors seem to have made the above claim, and yours was simply the most well-explained.)

Comment author: PhilGoetz 01 April 2010 09:21:17PM 0 points [-]

This argument could have been made by any intelligent being, at any point in history, and up to 1500AD or so we have strong evidence that it was wrong every time. If this is the main use of the anthropic argument, then I think we have to conclude that the anthropic argument is wrong and useless.

First, "the anthropic argument" usually refers to the argument that the universe has physical constants and other initial conditions favorable to life, because if it didn't, we wouldn't be here arguing about it.

Second, what you say is true, but someone making the argument already knows this. The anthropic argument says that "people before 1500AD" is clearly not a random sample, but "you, the person now conscious" is a random sample drawn from all of history, although a sample of very small size.

You can dismiss anthropic reasoning along those lines for having too small a sample size, without dismissing the anthropic argument.

Comment author: SilasBarta 31 March 2010 08:14:40PM 0 points [-]

Thank you for saying this. I agree. Since at least the time I made this comment, I have tentatively concluded that anthropic reasoning is useless (i.e. necessarily uninformative), and am looking for a counterexample.

Comment author: wedrifid 01 April 2010 01:40:37AM 0 points [-]

Disclaimer: I'm a little drunk.

Best time to do anthropic reasoning. Save the sane reasoning for when you're sober! ;)

Comment author: Jordan 27 March 2010 07:05:31PM *  3 points [-]

The anthropic principle is contingent on no additional information. For example, if sentient life exists elsewhere in the universe, your odds of being a human are vanishingly small.

True, assuming sentient life is common enough.

This would suggest sentient life does not exist elsewhere in the universe.

Not true. This is like saying that if you roll a million sided die and get 362,853 then the die must have been fixed because the chance of getting 362,853 is 1-in-a-million!

Comment author: Psychohistorian 27 March 2010 09:14:54PM -1 points [-]

if you roll a million sided die and get 362,853 then the die must have been fixed because the chance of getting 362,853 is 1-in-a-million!

Were that appropriate, the same mechanism would also defeat the reasoning in this post. While I agree with your ultimate conclusion, using solely the anthropic principle and no additional information, I believe you are compelled to conclude extraterrestrial life does not exist.

Comment author: Nick_Tarleton 27 March 2010 09:26:30PM *  1 point [-]

Were that appropriate, the same mechanism would also defeat the reasoning in this post.

I disagree. There is a natural category (sentience, reflectivity, etc.) that picks out humans over other Earthly animals and leads to a more-than-max-entropy prior for humans being more anthropically special*; this is not the case for either 362,853 or Earth.

* If you accept anthropic reasoning at all, that is. I'm sort of playing devil's advocate in this comment; this post mostly just pushes me further towards biting the bullet of UDT/collapsing epistemology to decision theory.

Comment author: wedrifid 27 March 2010 07:05:29PM 0 points [-]

The anthropic principle is contingent on no additional information. For example, if sentient life exists elsewhere in the universe, your odds of being a human are vanishingly small. This would suggest sentient life does not exist elsewhere in the universe. However, given that there appears to be nothing so special about earth that it wouldn't reoccur many times among trillions and trillions of stars, we can still conclude that sentient life does likely exist elsewhere in the universe.

With an acknowledgement that on topics of this difficulty I don't expect to be right a supermajority of the time I have to disagree both on what "I am human" tells me about other beings and on what extra information tells me.

Given no additional information, noticing that I am a human increases the probability that there is sentient life elsewhere in the universe (it at least shows that sentient life is possible). It is a mistake to draw any conclusions from p(a randomly chosen sentient being is a human | there are sentient beings elsewhere in the universe). If both you and aliens exist then you and aliens exist. Knowing that you happen to be you instead of an alien isn't particularly significant.

As for extra information... well, the fact that we can't see any evidence of interstellar civilisations eating stars or otherwise messing up the place does provide weak-to-moderate evidence that intelligent life is hard to come by depending on how likely it is for intelligent life to progress that far. In that case anthropic reasoning would help explain how we could come to exist given that life was improbable. We would be an unimaginably improbable freak and all other similarly improbable freaks would be off in other Everett branches.

Comment author: Psychohistorian 27 March 2010 09:23:15PM *  0 points [-]

Assume three possible worlds, for simplicity:

A: 1 billion humans. No ETs.

B: 1 billion humans, 1 million ETs

C: 1 billion humans, 1 billion billion billion ETs.

If I am using the anthropic principle and the observation that I am human, these together provide very strong evidence that we are in either world one or world two, with a slightly stronger nudge towards world one. Where we end up after this observation depends on our priors. I agree fully that making additional inferences, such as the probability of other sentient beings increasing due to our own existence, or when we look at the size of the universe, the odds of being alone decrease, affects the end probability.

The inference I described may be unduly restricted, but that is my exact point. The original post made an anthropic inference in isolation - it simply used the fact that there are more animals than humans, and the author is a human, to infer that animals do not have experiences. The form of the argument would not have changed significantly were it used to argue that rocks lack experience. Thus, while the argument is legitimate, it is easily overwhelmed by additional evidence, such as the fact that humans and animals have somewhat similar brains. That was my point: the anthropic principle is easily swamped by additional evidence (as in the ET issue) and so is being overextended here.

Comment author: PhilGoetz 27 March 2010 10:19:03PM *  10 points [-]

You're saying, "I rolled a die. The die came up 1. Therefore, this die probably has a small number of sides."

But "human" is just "what we are". Humans are not "species number 1". So your logic is really like saying, "I rolled a die. The die landed with some symbol on top. Therefore, it probably has a small number of sides."

Comment author: Strange7 27 March 2010 11:14:46PM -3 points [-]

If the die is small enough for you to hold in one hand, and the symbol covers only side yet is large enough to easily read with typical human visual acuity, based on the laws of geometry it would be safe to assume that the die has fewer than about 100 sides, yeah.

Comment author: Rain 28 March 2010 01:27:09PM 1 point [-]

I think this part of the analogy equates to our ability to observe the rest of the universe over billion-year time frames and its apparent lack of alien life forms.

The Doomsday argument is part observational, after all.

Comment author: AllanCrossman 27 March 2010 10:32:37PM *  3 points [-]

If the various species of ET are such that no particular species makes up the bulk of sentient life, then there's no reason to be surprised at belonging to one species rather than another. You had to be some species, and human is just as likely as klingon or wookie.

Comment author: wedrifid 28 March 2010 01:01:48PM 0 points [-]

If I am using the anthropic principle and the observation that I am human, these together provide very strong evidence that we are in either world one or world two, with a slightly stronger nudge towards world one.

And here is where we are in simple disagreement. I say that knowing that I am human tells me very little about the configuration of matter in a different galaxy. Things that it does not tell me include, but are not limited to, "is the matter arranged in the form of a childlike humanoid, maybe green or grey. Probably with a big head and that can do complex thinking?"

I claim (and, again, it is a complex topic so I wouldn't bet on myself at odds of more than one gives you, say, 20) that this argument isn't weak evidence that is easily overwhelmed. It is not evidence at all.

Comment author: timtyler 16 May 2010 07:51:33AM 0 points [-]

Re: "If the doomsday argument is sufficient to prove that some catastrophe is preventing me from being one of a trillion spacefaring citizens of the colonized galaxy, this argument hints that something is preventing me from being one of a trillion bats or birds or insects."

The doomsday argument? It seems like a dubious premise.

Comment author: PeerInfinity 30 March 2010 06:49:12PM *  0 points [-]

The following is copypasted from some stream-of-consciousness-style writing from my own experimental wave/blog/journal, so it may be kinda messy. If this gets upvoted, I might take the time to clean it up some more. The first part of this is entirely skippable.

(skippable part starts here)

I just read this LW post. I think the whole argument is silly. But I still haven't figured out how to explain the reasons clearly enough to post a comment about it. I'll try to write about it here.

Some people have posted objections to it in the comments, but so far none that clearly show the problem.

This is basically the same problem as with the doomsday argument, and anthropics in general. Generalizing from one example. Or, more accurately, trying to do statistics with a sample size of 1. Improbable events happen. If people experiencing this improbable event try to do anthropic reasoning about it, then they will conclude that "we just happened to be in this improbable category" is improbable, and therefore they are probably in some other, more probable category that gives the same results. And they would be right. They probably are in the more probable category. But some observers really are in that improbable category. And if they take actions assuming that they are in the more probable category, and not the improbable category, then they will be worse off as a result. But that won't be because they made a mistake in the math, it will be because they just happened to be in the more improbable category, and therefore any actions they take assuming that they are in the more probable category will be suboptimal.

Sorry, the above was confusing. I should rewrite it using specific examples, not general descriptions.

(skippable part ends here)

One standard example is the Doomsday Argument: It would be improbable for us to find ourselves in a low-population, pre-Singularity past, if there will be a future containing many orders of magnitude more observers. The conclusion of the doomsday argument is that there probably is no post-Singularity future, and that humanity will probably soon go extinct. And yes, that is what "the math" says. But it would be an extremely bad idea to assume that doomsday will inevitably come soon, and therefore there's no point in trying to do anything to prevent it. The math says that it's improbable to find yourself as one of the few people before the Singularity. The math doesn't say that it's impossible. There are still some people who will just happen to find themselves alive before the Singularity, and it would be a tragedy of epic proportions if these people, upon recognizing that their current situation is improbable, decide that there's no point trying to help make sure the Singularity happens, and turns out okay for everyone involved.

The same applies to the Simulation Argument: If there is a post-Singularity future that contains lots of ancestor simulations, then it would be improbable for us to find ourselves in the real pre-Singularity universe, rather than one of these ancestor simulations. And yes, that is what "the math" says. But it would be a tragedy of epic proportions to assume that you must inevitably be in one of these simulations, and therefore there's no point in trying to help make sure the Singularity happens, and turns out okay for everyone involved. Oh, and it would also be a good idea to try to prevent any ancestor simulations from being created in the future. Or at least that's my opinion, as someone who doesn't want to be in an ancestor simulation.

So, now how does all this apply to that LW post? Oh, right, assuming that animals are probably not conscious. The math is less clear in this case, but even if the math turns out to be correct, it would still be a bad idea to forget about that word "probably". It would still be tragic to guess wrong about whether animals are conscious, and treat them cruelly for your own benefit as a result. And, as some commenters pointed out, the probability of guessing wrong is quite high. And so:

(probability that animals are conscious) x (suffering caused by treating animals cruelly) > (probability that animals are not conscious) x (minor inconveniences to yourself caused by not treating animals cruelly)

Or at least that's my guess. I could be wrong.

Comment author: Rain 01 April 2010 05:26:03PM 0 points [-]

Peter Thiel uses similar arguments about investing for the future: if it all goes bust, then your investments don't matter either way, but if it turns out okay, then you win big. No down side vs. huge up side: invest.

Comment author: Mallah 30 March 2010 05:15:31PM 0 points [-]

Another reason I wouldn't put any stock in the idea that animals aren't conscious is that the complexity cost of a model in we are and they (other animals with complex brains) are not is many bits of information. 20 bits gives a prior probability factor of 10^-6 (2^-20). I'd say that would outweigh the larger # of animals, even if you were to include the animals in the reference class.

Comment author: bogus 30 March 2010 09:00:39PM *  -1 points [-]

The complexity cost of a model in which any brain is conscious is enormous. Keep in mind that a model with consciousness has to 'output' qualia, concepts, thoughts... which (as far as we can tell) correspond to complex brain patterns which are physically unique to each single brain.

That is, unless the physical implementation of subjective experience is much simpler than we think it is.

Comment author: grobstein 30 March 2010 04:20:08PM 0 points [-]

If there is an infinite number of conscious minds, how do the anthropic probability arguments work out?

In a big universe, there are infinitely many beings like us.

Comment author: Wei_Dai 30 March 2010 06:37:41AM 0 points [-]

An (insufficiently well designed) AI might use this kind of reasoning to conclude that it's not like anything to be a human. (I mentioned this as an AI risk at the bottom of this SL4 post.)

Comment author: timtyler 27 March 2010 04:14:03PM *  0 points [-]

Re: "Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal."

Your priors say that you are a human. It is evidence that is hard to ignore, no matter how unlikely may seem. Concrete evidence that you are part of a minority trumps the idea that being part of a minority is statistically unlikely.

Since this is true regardless of whether or not it "feels like something" to be a bat, the mere evidence of your existence as a human doesn't allow you to draw conclusions about Nagel's bat speculations.

Comment author: Pablo_Stafforini 03 April 2010 01:27:36PM *  -3 points [-]

Instead of showing that non-human animals are unconscious, anthropic reasoning may show that such animals are conscious if we are not ourselves soon doomed to extinction. Expanding the class of observers to include such animals makes it less surprising that we find ourselves living at this comparatively early stage of human evolution, since "we" refers to conscious rather than to merely human beings.

This argument assumes that most non-human animals will soon go extinct. But this assumption makes sense under many of the possible scenarios involving human survival.

Comment author: Desrtopa 07 January 2011 04:13:57PM 0 points [-]

If you randomly selected from the set of all sentient beings throughout time and space, the odds are vanishingly low that you would get the Little Prince as well.

Suppose that he ponders his situation, and concludes that if there were places in the universe where many, many humans can coexist, then it would be unlikely that he would find himself living alone on an asteroid.

If we accept for the sake of an argument that he exists, then someone must be the Little Prince, and be doomed to make incorrect inferences about the representativeness of their situation.

It makes no difference to the Little Prince's observations whether he is the only being in the universe, or in a heavily populated universe where he simply happens to find himself completely isolated.

Similarly, it makes no difference to our observations whether our future contains a mass extinction event or a population explosion. A universe where our future contained a population explosion would contain a vantage point equivalent to our own just as one where our near future contained an extinction event would.

For any individual, the answer to the question "is my situation typical?" is more likely to be yes than no, at least for sufficiently broad definitions of "typical." But that doesn't mean that the answer can't be "no," and unless you define "typical" so broadly as to be meaningless, sometimes it has to be. If you see a possible future event that would render all present and past existences atypical, you can't use anthropic reasoning to determine whether it's likely to happen, because the universes in which the event doesn't happen and the ones where it does still contain the same vantage points prior to it.

Comment author: Will_Sawin 10 January 2011 01:03:23AM 1 point [-]

The logical conclusion of that version of the anthropic principle is that the universe contains infinitely many copies of us.

Comment author: CannibalSmith 30 March 2010 11:35:03AM -1 points [-]

Can we dismiss all anthropic reasoning by saying that probability is meaningless for singular events? That is, the only way to obtain probability is from statistics, and I cannot run repeated experiments of when, where, and as what I exist.

Comment author: wnoise 30 March 2010 04:35:01PM 4 points [-]

That's entirely contrary to the Bayesian program that this site broadly endorses: throwing out the subjective probability baby with the anthropic bath water, as it were.

Comment author: CannibalSmith 31 March 2010 01:33:00PM *  0 points [-]

What, really? Wait, what!? Uh.

  1. Could you please answer my question directly in the form of "yes/no, because"?
  2. Do you mean by subjective probability the fact(?) that probability is about the map and not the territory?
  3. If yes, what does it have to do with anthropics?
  4. If yes, what! Contrary?? I learned about it here!
  5. If no, I'm completely confused.

Also, dear reader, vote parent up or down to tell me whether he's correct about you.

Comment author: Morendil 31 March 2010 01:46:12PM 3 points [-]

No, probability is not "meaningless for singular events". We can meaningfully discuss, in Bayesian terms, the probability of drawing a red ball from a jar, even if that jar will be destroyed after the single draw. The probabilities are assessments about our state of knowledge.

Therefore no, we cannot dismiss all anthropic reasoning for the reasons you suggested.

If you got "probability is meaningless for singular events" from what you learned here, either you are confused, or I am. (Possibly both.)

Comment author: wedrifid 31 March 2010 02:21:15PM 2 points [-]

Can we dismiss all anthropic reasoning by saying that probability is meaningless for singular events?

No, because it isn't isn't meaningless.

That is, the only way to obtain probability is from statistics

No, you can get it from mathematics. Even basic arithmetic. Infinite series of events, on the other hand, those are hard to come by.

, and I cannot run repeated experiments of when, where, and as what I exist.

I dismiss many examples of (bad) anthropic reasoning because they assume that that the probability of their subjective experience is what you get if you draw a random head out of a jar of all things that meet some criteria of self awareness.

Do you mean by subjective probability the fact(?) that probability is about the map and not the territory?

Kind of. Read Probability is subjectively objective

If yes, what! Contrary?? I learned about it here!

The frequentist dogma was the 'contrary' part, not the 'maps/territory' stuff. Probability doesn't come from statistics and definitely applies to single events.

Comment author: wnoise 31 March 2010 03:30:49PM 0 points [-]

Statistics is, of course, one source of knowledge we can usefully apply in calculating probabilities.

Comment author: thomblake 31 March 2010 01:54:54PM 0 points [-]

It seems to me that the disagreement here is because you're looking at different parts of the problem. It might well be said that you can't have a well-calibrated prior for an event that never happened before, if that entails that you actually don't know anything about it (and that might be what you're thinking of). On the other hand, you should be able to assign a probability for any event, even if the number mostly represents your ignorance.