Combinatorial Explosion

More blog material culled from Will Wilkinson's comment threads...

MK, who has clearly watched Minority Report one too many times, writes:

I think our term “free will” is a pragmatic way of interacting with humans for whom our best prediction mechanism is at the level of beliefs/desires/etc. If we really could take a supercomputer and predict your actions based on atoms, all hell would break loose. We would be like the remote tribe who you show them a camera and it completely blows their freaking mind.

The supercomputer is not logically impossible and it could happen someday.

The moral perspective is interesting here. If we could predict people’s actions precisely, does it change morality? Well yeah it does. Game-theoretically, uncertainty has just been radically reduced. The optimal “play” now involves locking people up who are about to do something bad. Or, showing them the supercomputer results so they know they are at risk and can take some classes and otherwise “shape up” appropriately.

We already try to do this. If you commit enough crimes, we predict you will commit more so we lock you up for life. If you get a DUI, we predict you will drink more in the future so we mandate AA meetings. With a predictive supercomputer, it’s the same thing except we do it more preemptively.

This is not wrong. Society would be much improved.

Putting aside the questions of justice surrounding prior restraint, I'd like to focus just on the question of the logical impossibility of the Laplace's demon scenario.

In the first chapter of Consciousness Explained, Daniel Dennett tackles the very similar issue of brain-in-the-vat scenarios and argues that while these sorts of technological achievements are not logically impossible, their practically is highly unlikely, given the enormous computing power they would require and the extremely low pay-off for systematically predicting an individual’s actions. The information processing capacity and continual feed-back loops necessary to achieve such a feat would be prohibitively costly and unlikely to ever be as complete or convincing as mere logical possibility would imply. Mathematically, this practical (though not logical) limit is a result of combinatorial explosion. So, if you buy Dennett's argument, there is no need to worry that you are currently a brain in a vat or that Tom Cruise will be arresting you for crimes you have not yet committed.

Incidentally, I don't know if our co-blogger Patri has ever read any Dennett, but Patri seems to have independently developed the same objection as Dennett to Nick Bostrom's Simulation argument, a combined technological/economic "impossibility" argument. Maybe this stuff just comes naturally to those more familiar with computer engineering and combinatorics than to regular old philosophers who focus too much on mere logical possibility.

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Laplace

Micha, I think quantum uncertainty pretty much rules out Laplace's demon conceptually as well.

In any case, I think Michael Polanyi presents an even stronger argument for the irrelevance of that demon to the problems it supposedly 'solves' -- let's say the demon did exist, says MP. The information it would give us would be vast plots of particle positions at all times, or something of the sort, which would be of no help whatsover in answering questions like "Is Gene Callahan about to commit a crime?" It seems to me as being extremely unlikely that we could even identify what makes up 'Gene Callahan' in the particle data!

Philosophy Bashing is Naive

I don't get it. The objection to the brain in the vat scenario is that it would take a lot of computing power? But how do we know that the universe within which the vat sits doesn't have limitless energy, or some even weirder characteristic that allows for easy to make brain vats? I mean, if you're willing to grant the possibility the brain's in a vat, seems to me you should at least be willing to grant the possibility of powerful vat generation technology, or some such.

Or are you just talking about a device that could predict human behaviors? If so, yeah, the argument may go through--may not, I don't know. But it seems to me you're conflating two different things--radical skepticism and the practical limits to prediction. I'm not sure, not having read Dennett's book.

It's not quite philosophy

It's not quite philosophy bashing, since Dennett himself is a respected philosopher. It's bashing some philosophers for not being up to date on the relevant science and math.

The objection to the brain in the vat scenario is not simply that it would take a lot of computing power. It's that the more realistic you want brain in the vat technology to become, the more complex the information processing and the necessary feed-back loops become, exponentially, leading to combinatorial explosion. Moreover, the economic argument suggests that there are cheaper ways to go about simulating reality, and that is generally by incorporating certain parts of reality within the simulation, which is cheating for the purposes of the argument, but there is no reason not to cheat in the real world.

While infinity is understandable as a logically possible proposition, it is not a practically possible one, so there need not be any strong epistemic reason for radical skepticism.

You haven't read Dennett's book yet? I can't believe you got all the way through your philosophy of mind phase without reading it.

I Still Don't Get It

Ah, then just bashing of "regular, old philosophers"?

The reason for radical skepticism doesn't have to do with the pragmatic production of it, so far as I'm aware--I doubt Descartes thought someday humanity was going to produce a great Deceiver and that's what worried him. We don't think: "Hey, you know Bob's Brain in a Vat Spa down the street? What if I'm really in one of those vats?" We think: "Hey, it's possible I might be a brain in a vat! None of this is real!"

It's the logical possibility that's needed to make the skepticism scary--nothing else, because once you concede it's possible, you're ready to concede all other kinds of things, like it's not only possible, but that it's possible that in some world it's also practical--and you might be in that world! I'm repeating myself, but I don't see how you've responded to any of what I said (perhaps you didn't intend to--if you're simply summing up another's argument, then that's fine).

I did read Goedel, Escher, Bach and The Mind's I, and quite a few of Dennett's journal publications, but no, not CE. I admit I can't stand the guy, but I should read his book one of these days.

Perhaps you can tell me: in the chapter of CE that you refer to, does Dennett intend his argument dealing with combinatorial explosions, et al, to be a criticism of the radical skeptic's position, or simply of the idea of being able to very accurately predict human behavior? Because if it's the former, it seems trite.

First of all, are you

First of all, are you familiar with Nick Bostrom's Simulation argument? He is not merely arguing that the brain-in-the-vat scenario is logically possible, but that it is practically likely, given certain other conditional assumptions. Here is the abstract:

This paper argues that at least one of the following propositions is true: (1) the human species is very likely to go extinct before reaching a “posthuman” stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation. It follows that the belief that there is a significant chance that we will one day become posthumans who run ancestor-simulations is false, unless we are currently living in a simulation. A number of other consequences of this result are also discussed.

Patri's response was to deny (2): any sufficiently advanced technological civilization capable of running such simulations would have very little interest in doing so.

once you concede it's possible, you're ready to concede all other kinds of things, like it's not only possible, but that it's possible that in some world it's also practical--and you might be in that world!

I think this is what Dennett is denying; that the focus on logical possibility is misguided, because it just isn't the case there there are possible worlds in which this sort of thing is practical, at least given our current understanding of technological capability. Of course, if we let ourselves imagine some completely unimaginable sorts of technology and economic incentives, we can imagine a possible world in which it is practical. But I think Dennett is arguing that imagining this sort of unimaginable thing is not a legitimate step for philosophers to take.

You can read the first few pages of Dennett's combinatorial explosion argument on the Amazon preview pages, but it cuts off before the chapter is finished. Still, what is there might help clarify his argument better than I can do.

I know Bostrom's argument,

I know Bostrom's argument, but I wasn't questioning Patri or anyone's response to that--it's not a very good argument to begin with, and I feel no need to protect it. I was questioning Dennett's presumed attempt to tackle radical skepticism. I'm still not sure if that's what he's trying to do. Please, tell me, is he?

I think this is what Dennett is denying; that the focus on logical possibility is misguided, because it just isn't the case there there are possible worlds in which this sort of thing is practical, at least given our current understanding of technological capability.

Again, I don't get it. It just is the case that there are possible worlds where this is practical. I can imagine such worlds easily--worlds with huge reservoirs of energy, or whatever raw material is needed to make practical the production of brain-in-vat technology. The only way I can see to give this argument any bite is by denying that it is logically possible for a world to have practical brain-in-vat capabilities. But that's quite a high standard to meet. Do you have such an argument?

To repeat, my questions:

1. Is Dennett's argument supposed to defeat radical skepticism? Or just the practical ability to accurately predict human behavior? Or is he simply going after Bolstrom's argument in particular and not the classic "we may just all be brains-in-vats, oh no" arguments?

2. If Dennett is going after the classic brain-in-vat arguments, is he denying the logical possibility of worlds where such vats are practical? If yes, why?

Of course it's perfectly all right to just tell me to shut up and read the book myself, but I thought you might know these things offhand, since you were referencing Dennett's argument in the post.

It's about how the brain works

The brain in the vat conclusion is not Dennett's main point. In fact Dennett acknowledges that this doesn't defeat the argument that it is possible in principle. Dennett's actual point comes out later in the same section, in which he begins to sketch out a generate-and-test theory of perception.

What do you think about

What do you think about Dennett, Constant? I personally find his arguments persuasive, but then I haven't really read much by his critics.

Dennett is one of my favorites

I find that his positions are close to my own. I think his way of thinking is fruitful. If I disagree with him on anything significant, it doesn't come to mind.

Alas, I'm Guilty, Too

I personally find his arguments persuasive, but then I haven't really read much by his critics.

We are all slave to confirmation bias. I've read many reviews of Chalmers' book, but I'm well aware I go easier on his detractors than his supporters.

(But if you want see popcorn-worthy Dennett fights, check out him and Searle duking it out in the NYRB, or Dennett v. Orr in the Boston Review, all available online.)

Thanks, I'm printing those

Thanks, I'm printing those three articles and will read them when I get a chance. I was really impressed with Orr's review and takedown of William A. Dembski. I've never really been impressed with anything Searle has had to say.

I can imagine such worlds

I can imagine such worlds easily--worlds with huge reservoirs of energy, or whatever raw material is needed to make practical the production of brain-in-vat technology.

But can you imagine such a world given our world's current understanding of physics and our world's current understanding of technological potentials? Sure, it is logically possible to imagine different physical laws and thus different technological potentials, but not given what we know about the world. Of course, what we know about the world is (at least to some extent) a function of our experience of the world, so if our experience was being simulated and manipulated all along, we might have no way of knowing the "givens".

1. Is Dennett's argument supposed to defeat radical skepticism? Or just the practical ability to accurately predict human behavior? Or is he simply going after Bolstrom's argument in particular and not the classic "we may just all be brains-in-vats, oh no" arguments?

No, he is not trying to do any of these things, at least not directly. He is simply shifting our focus away from the methods some philosophers use of outlandish examples within the bounds of logical possibility, and instead toward thinking through the mechanics and engineering of how things like brains, sensory organs and conscious experience actual work if we were to try to reconstruct them using a simulation experiment.

2. If Dennett is going after the classic brain-in-vat arguments, is he denying the logical possibility of worlds where such vats are practical? If yes, why?

He is denying the (practical) possibility of such experiments given what we know about how human sensation and consciousness works and the technological obstacles inherent in trying to simulate interactive experience through mere nerve signals without in the process cheating and creating an actual, physical reality.

Flummox: Today's Word of the Day

But can you imagine such a world given our world's current understanding of physics and our world's current understanding of technological potentials? Sure, it is logically possible to imagine different physical laws and thus different technological potentials, but not given what we know about the world.

"[G]iven what we know about the world" we're not brains-in-vats in the first place! So this all misses the point of the radical skeptic's thought experiment.

If one wants to deny that reality can be so deceptive, one should merely deny it at the step where we imagine we're brains-in-vats, not later on, when we're imagining the production of said brains-in-vats. Otherwise one gets to a point where they're allowing in some imaginable possibilities (we could be brains in vats) but not other imaginable possibilities (brains in vats could be practical to construct), with one's discretion as to which imaginable possibilities are allowed in seeming entirely arbitrary, and thus, unpersuasive.

To be sure, if you ask me to hold certain things as given, it constrains what I can logically conceive. But the point of the classic brain-in-vat example is that there isn't anything to hold as a given (save one's own consciousness, a la Descartes).

[Dennett] is simply shifting our focus away from the methods some philosophers use of outlandish examples within the bounds of logical possibility, and instead toward thinking through the mechanics and engineering of how things like brains, sensory organs and conscious experience actual work if we were to try to reconstruct them using a simulation experiment.

Incidentally, I don't think any of this flows from Dennett's argument, as you've stated it, but that's a different issue.

At any rate, I'm afraid your original post still flummoxes me--i.e., we still have plenty of reason to worry we're brains in vats. We simply don't have to worry about being one if we take as given certain physical constraints in the world that contains the vat--but, as I've hope I made clear, that's not much consolation.

To be sure, if you ask me to

To be sure, if you ask me to hold certain things as given, it constrains what I can logically conceive. But the point of the classic brain-in-vat example is that there isn't anything to hold as a given (save one's own consciousness, a la Descartes).

True, practical possibility (practical given "known" laws of physics) is a looser and weaker standard than logical possibility. But that's sort of the point. If our known laws of physics and levels of technology were more congenial to brain-in-vat experiments, we would have more reason to fear actually being brains in vats. Having to artificially simulate both the content of reality and an alternative set of physical laws is a more daunting task, and thus less likely - or harder to imagine. The "real" set of physical laws in the meta-reality are congenial to brain-in-vat experiments, while the simulated, fake set of physical laws in the sub-pseudo-reality are not congenial to this sort of experiment.

Although, from a designer's perspective, creating a child pseudo-reality with a different set of physical laws would make sense if the designer does not want his children making child realities of their own...

At any rate, I'm afraid your original post still flummoxes me--i.e., we still have plenty of reason to worry we're brains in vats.

Correct, we still have some reason for worry. Since the combinatorial explosion argument is not meant to be a logical possibility argument, it does not presume to remove all doubt. It attempts merely to reduce worry, because Bayesian reasoning/Occum's razor makes us less likely to believe both that the (non-physical law) content of reality is artificially constructed and that the physical laws of reality are constructed as well, relative to the proposition that only the content but not the physical laws are constructed, which itself is close to (but not equivalent to) logical impossibility.

We simply don't have to worry about being one if we take as given certain physical constraints in the world that contains the vat--but, as I've hope I made clear, that's not much consolation.

Well, I think it is some consolation - maybe not as much as you would have liked, but significant nonetheless. When we look at the problem from the perspective of potential reality designers, we see how much more difficult it is to trick test subjects about some things (artificial physical laws that conflict with the "real" physical laws that govern meta-reality; interactive sensory signals such as the pressure feedback involved with touching an object) than it is to trick test subjects about other things (simple hallucinations that build off of real sensory date).

Imagine three possible worlds. One is entirely "real", with no simulation or trickery. One is entirely fake, with everything in it, including physical laws, being artificially constructed from the ground up and entirely divergent with the "real", meta-reality in which it exists as a child. And the third kind of world is somewhere in between, with certain aspects artificially simulated and other aspects borrowed from the real world. It seems that when deciding which sort of world we are most likely to reside in, we should place greater probability on the third kind of world than on the second, since it involves a greater multiplication of assumptions and a greater amount of effort on the part of the "designer."

Don't Think So

Micha,

You haven't answered any of my objections.

If our known laws of physics and levels of technology were more congenial to brain-in-vat experiments, we would have more reason to fear actually being brains in vats.

No, we wouldn't. Because our known laws of physics, etc., are the laws of physics of what you're presuming is a fake. You can't extrapolate without presuming some thing about the meta-reality our vat is in; but since all we know is distortion, there's no way to make that presumption. If you want to presume it, go ahead. But I could just as easily presume I'm not a brain in the vat in the first place.

To be clear, when I said "little consolation" what I meant was "a vanishingly small amount of consolation." I say this because you seem to be accepting all my points, under the impression that the worries I list are tiny. But I want it clear I think all the worries I've listed are huge, and the minor consolation the initial combinatorial explosion argument provides is too tiny to mean anything.

The second general problem plaguing Wilson's book is one of philosophical naiveté. We scientists are, of course, notorious for thinking all philosophical problems straightforward. Scientists tend to swagger into town, confident that a bit of straight shooting will set all aright. Though typically modest, Wilson slips into this cowboy role all too easily. A number of philosophical problems-- mind-body, free will, the failure of logical positivism-- pop up in the course of his book. And Wilson guns them down at a staggering rate. Unfortunately, his solutions are often surprisingly superficial. In the end it's hard to escape the conclusion that Wilson often just doesn't see the problem. He sees half of it, or less than half of it, and sets diligently to whittling away at some corner of it. When he announces his solution--often in a one-liner--he seems mildly astonished that no one previously saw so simple an answer.

Orr

Vat-ophobia

Both of you seem to be suffering from some kind of vatophobia. What's to fear about living in a simulated world? It doesn't make you any less "real". If some heirarchically alien mad scientist is really running some simulation then you in fact are real. You are made of the real stuff of his world.

As far as I can tell your main fear is not your reality but the fact that you cannot ground your beliefs. You want to be foundationalists. You want knowledge to have a ground floor.

Problem is that even the statement "I think therefore I am" does not ground ones knowledge. Implicit in that statement is the concept of "I" and that is something you can be profoundly mistaken about. I'm not sure Dennett gets it but that is part of the importance of the illusions of consciousness that he is fond of pointing out. Not merely in showing the consciousness is manufactured but that it is foundationless.

My apologies to Dennett if I've got him wrong on this as although I've read him deeply I haven't read him recently.

The reason why scientists swagger in to cowboy the problems of philosophy is that they have implicitly accepted the foundationlist nature of knowledge. The essence of Popper is right if even he gets some individual issues wrong. People who think like scientists really don't see many of these "problems".

From the perspective of understanding that all knowledge is ultimately foundationlist there is no need to worry about having absolute proof that we are not brains in vats. Why? Because we never have absolute proof of anything. The fact that there is absolutely no evidence that we are brains living in vats or that our universe is a simulation is all we need to "feel safe" about our beliefs.

Biologists will tell you that bacteria are just as "evolved" as humans from the perspective of how long they have been evolving. From the perspective of "groundedness" the belief in a reality outside the self is just as grounded as a belief in conciousness itself. Why? Because both are "groundless" if you are looking for ultimate foundations.

For me the knowledge that there world outside the self is just as "real" as any inner activity. In fact, my mental model of the world actually percieves it as "more real" than my conscious thoughts. That is as it should be. I certainly am much more contengent than the rest of the world. In fact, some day, hopefully a long way off, I will no longer exist.

If you are truly in fear of the reality of your existence perhaps you should be reading books by Aubrey de Grey, and not Chalmers. Hell, Chalmers isn't even good in noodling out his own area of expertise. Zombies, really?

Quee Nelson

Speaking of brains in vats, I've been reading The Slightest Philosophy, by Quee Nelson. Almost done. I've enjoyed it quite a bit. Some of it is highly reminiscent of, in fact borrows a good bit from, J. L. Austin's Sense and Sensibilia, another highly readable book.

Quee and Austin

Constant, thank you very much for mentioning and complimenting my book. I appreciate your kind words, and welcome any additional feedback for a second edition!

For example, I'm wondering what in my book you perceive as "borrowed from" Austin. I confess I did not read more than a few pages of the Austin before writing The Slightest Philosophy, but I had meant to. (I have an excuse: I had bought the book, and had read only a few pages--which I loved--but then mislaid it somewhere. For several years it drove me nuts that I knew I needed to read that book, but I refused to let myself buy another copy, because I knew I already owned one, if only I could just find it! And the only reason I couldn't find it, was because I had already spent so much of my husband's hard-earned money on books that our large house was bursting at the seams with them. If I allowed myself the policy of buying a second copy of any book I couldn't find, the poor man would finally be driven to beat me. Besides, I knew the book was right under my nose somewhere, and I would find it--any minute. Finally, too late, I found the Austin in a slim compartment in an old suitcase we had stopped using, forgotten in the back of a luggage closet.)

Now I have read most of the Austin, but not quite finished it. Isn't it true that he sort of "gives up" at the end, when faced with skepticism? It is one of the central purposes of my book to take the Vat's bull by the horns and to defeat skepticism to the complete satisfaction of the reader. Most of the heavy lifting for this is in my last chapter, "Doubting Skepticism." So, you might say that my book represents how, in my view, Austin's book should've gone but didn't. However, I'd like to hear your opinion on this.

Of course, now that I've belatedly read the Austin, I'm incorporating some of its helpful pointers (like to crucial Ayer passages for my Appendix) into my second edition.

Because I'm so ignorant

I haven't read many books along the lines of Austin's book, so that's a bit of a solitary reference for anything remotely resembling his line of argument. Anyway, to give an example of what I mean, on pages 29-30 of my copy of the book Austin discusses a bent stick in the water, and he says, among other things,

Well, we are told, in this case you are seeing something; and what is this something 'if it is not part of any material thing'? But this question is, really, completely mad. The straight part of the stick, the bit not under water, is presumably part of a material thing; don't we see that? And what about the bit under water? - we can see that too. We can see, come to that, the water itself. In fact what we see is a stick partly immersed in water; and it is particularly extraordinary that this should appear to be called in question - that a question should be raised about what we are seeing - since this, after all, is simply the description of the situation with which we started.

And here's a bit from your book:

PROFESSOR: "No good. Look, it's very simple. The oar you see is bent. But the real oar in itself is straight. Therefore, the oar you see, is not the same oar, as the real oar in itself."

STUDENT: "Poppycock. 'The oar I see' is the real oar in itself, the straight oar."

This popped out at me because I remembered it from Austin's book, but what I really have in mind is not any list of similar examples (this is the only one that popped out) but a similarity of approach, which is being illustrated here. The student says, "Poppycock. 'The oar I see' is the real oar in itself.", and Austin writes, "But this question is, really, completely mad. [...] In fact what we see is a stick partly immersed in water.' You both attack the argument from illusion right at root, right at the beginning of the sleight of hand.

I'm on page 201, so I haven't gotten all the way through yet and can't comment on the end. Life intervenes and I work my way through books very, very slowly.

I can't thank you enough for presenting the argument as a dialog.

The Bent Oar

Actually, the Bent Oar case is a famous one from the ancient Greco-Roman philosopher Sextus Empiricus, a guy who might be my candidate for the title of founder of postmodernism, if you can stand the anachronism. Sextus Empiricus is at least as important and influential in the history of Western thought as anybody who ever lived. He's a must-read. Also see Richard Popkin's superb History of Scepticism, another must. Interestingly, I think Sextus got his ideas from some "Hindu philosophers," if I remember rightly, while traveling with Alexander the Great?

Make that Pyrrho

Sorry, the Greek philosopher who picked up skepticism from Eastern philosophers while traveling with Alexander the Great wasn't Sextus but Pyrrho, of course. (I knew that!) Sextus then made these ideas famous with his work on the subject, titled "Outlines of Pyrrhonism."

Bend Sticks

"The Evidence of the Senses" by David Kelly also covers the issue of bent sticks. So this is a common theme. I thought he did a good job of clubbing skeptics with nonexistent sticks.

David Kelley

I like Kelley too. But my strategy is very different. I don't want to try to put a special, unequal "burden of proof" upon the skeptic. Of course, no skeptic could overcome such a burden. It's like taking candy from a baby. But I think I ought to beat the skeptic fair and square, on a level playing field. I also think it's important for me to be able to uphold my claim that nowhere do I need to take anything for granted.

I believe Kelley once had Rorty as professor. I envy him that.

That Reminds Me

This seems as good a time as any to thank Micha for his lucid argumentation--while I disagree with it, at least it's comprehensible. Things could, apparently, be different.

Too Bad

Too bad you didn't understand. I solved your problem right there.

Not much of a debater

Don't know how he is offline, but online Scott doesn't like to debate - at least, with certain unsavory types (like you and me). He has an unfortunate habit of not just failing to reply, but replying and, in his reply, blaming the other party for his own refusal to debate. Thus, for example, you are supposedly unclear. Of course, any unclarity could be cleared up with a little back and forth between you and him, so it's not a very significant point. It was, frankly, pointlessly rude for him to go out of his way to say it. Elsewhere, rather than just remaining silent in reaction to comments, he writes an addendum to his post claiming that David Chalmers has already dealt with everything and it would be boring to rehash everything. Again, this is not a very significant point, because even a brief back and forth would quickly take the discussion to a point beyond Chalmers's latest reply. Moreover, philosophy is at least ninety percent, probably ninety nine percent, rehashing what has already been said. It's just the nature of the thing.

You also failed to mention

You also failed to mention that Scott is the anti-christ.

I was saving that for later

That was going to be my knock down argument for when I really needed something big.

Me: ... and since 7x7=48, my argument is complete and without flaw.

Scott: But 7x7=49.

Me: You're the Antichrist!

Thank You

I saw the comment title and figured this was aimed at me. Give that the Freudian reading you will.

So a few things:

1. I think you, perhaps greatly, overestimate the clarification possible by "a little back and forth."

2. I do find Brian unclear and confused, even compared to those on his own side on many issues--say Micha. Or you. If it's rude to say so, so be it, but I thought it clear that the other party's bringing in an unrelated point in an attempt to pick a fight--"Zombies, really?"--made my move not terribly unfair. Reasonable people can disagree on my justification. In retrospect, I probably should have simply been silent.

Perhaps other people find Macker more comprehensible than I do. I doubt it, personally, but it's perfectly possible the failure is my own. And sometimes people are just speaking at different wavelengths. Some people, for instance, hate Magnolia, while I love it. Some people seem to find the zombie argument laughably bad--I do not.

3. I never said Chalmers had dealt with everything. At least, not to my knowledge--give me one moment to recheck the addendum on my prior post. On second reading, there may be some ambiguity in what I wrote, so let me make clear now I think it's definitively not the case that Chalmers has "dealt with everything," and I apologize if my response could be read otherwise. There are giant chunks of the philosophy of mind he's only grazed. I don't even think he's dealt with everything relevant to the zombie argument.

4. I agree that much philosophy is repetition. Much of everything is, as I see it, repetition. But I see no reason to add to that repetition needlessly, especially in an age where primary materials are a click away, where arguments that have been made by more eloquent and learned authorities than me can be viewed by those truly interested in the relevant discussion.

5. You say I don't like to debate. I would think, given my participation in threads here and elsewhere, that that's obviously untrue. Indeed, I like to debate too much, and have an irrational habit to devote time with far worthier uses to arguing trivial points on esoteric subjects on comment threads no one will read with minimal hope of furthering my knowledge or the other party's--and this is largely a function of pride (I do not think I'm the only one with this foible).

It is this habit I try to curb by bailing out of discussions when they become tiresome, or devoted to nitpicks, or a sense of deja vu sets in, or the whole thing is markedly similar to debates others have already had many times, or it threatens to devolve into silliness, or it's clear the winner of the "debate" will only be he who has the most free time. Sometimes I leave when people seem so obviously wrong or uninformed I doubt their devotion to the truth and thus, the utility of further or any discussion. Sometimes the points being made are good and require thought and I set about to think on them. I certainly disown any obligation to defend views I've not adopted, or views I hold very weakly.

And, sometimes somebody is making the points I would make were I in the debate (often better than I could), so my entrance can only be superfluous. And sometimes, I bail out because I have something else to do--perhaps I'm busy debating somebody on some other thread somewhere else, or perhaps I'm debating someone in real life. Maybe I'm writing to some well-known philosopher to see if he has a response to what I think is a good argument against his position (incidentally, what led to my zombie post). Maybe I'm in the bathroom.

In short, I try to debate to learn something or teach something--I do not care--or at least, I strive to approximate the behavior of one not caring, however imperfectly--about winning the debate. In weaker moments, I debate for want of anything better to do, but these weaknesses are becoming rarer. If this gives off the impression of me not liking debate qua debate, I think I must be doing something right.

And, since you seem curious, offline I try to embrace a similar policy, when I'm not raining down fiery death upon my enemies or watching reruns of Friends. (I actually don't do either of the latter, but Micha has accused me of being the Antichrist, and those sound like things the Antichrist would be into.)

Quitting a debate is fine

I wasn't criticizing you for declining to debate or for quitting a debate. I was criticizing you for blaming the other guy. If you don't want to deal with Brian, that's not his fault. Your response to him seemed gratuitously unkind. The indirectness of it (praising Micha, implying the criticism of Brian) suggests that you yourself realized that it was unkind.

Beat the Vat

Scott, since you've here taken up the role of Attorney for the Skeptic (even if you aren't actually a skeptic), I'm addressing this reply to you. My book, mentioned by Constant, below, undertakes to address and answer your arguments. (Note: you don't have to buy the book to read a lot of it for free at Google books.) For example, in a nutshell, I insist that:

1) Neither side can be saddled with a special, unequal "burden of proof."

2) Infallible certainty is not required in order to know things; rather, it's a comparative-plausibility contest between rival explanations, with a coherent fit to the data as the criterion, justified by the fact that's pretty much the definition of truth.

3) The Vat story must (really and truly) be an actual possibility, and this means it must be more than a merely logical possibility. It must ALSO be a physical possibility.

4) However chancy the Mundane Story (you're not in a vat) may be, therefore, the Vat Story can only be relatively even more chancy. The Vat Story depends upon the real existence, for example, of vats, since any argument that the Vat Story really could--physically--work, will rest upon the plausibility of our mundane beliefs about what can, as a matter of fact, physically work.

If you doubt this last claim (4), then ask yourself, for example, why did skeptics replace the Cartesian Demon with the Vat? Why did the Demon go out of style? Either I'm right about (4), or the Demon argument should be just as good as the Vat argument. Right?

(Sorry, the book is a lot easier to understand than this post! That's why it's longer.)

Quee, Sorry for not

Quee,

Sorry for not answering earlier. Thanks for your response. I don't think you want a response from me, since I'm in a position of ignorance regarding what are obviously much more detailed arguments in your book.

For the record, no, I'm not actually a skeptic.

Zombie Lawyer

Quee,

He's just trying to prove that lawyers don't have consciousness, um, err, consciences.

Philosophy Bashing

Philosophy Bashing, isn't that what philosophers are paid to do all day long?

Just stumbled on this post...

Just stopped by and saw the post.

Short answer: you may be right that it could never practically happen, though predicting the very remote future is quite hard as we know.

Nevertheless, rest assured we will get better at cracking our heads open (metaphorically speaking) and using the observations of the neurons in a person's head to predict their actions.

We may never really "solve" the prediction problem in a snazzy complete way, but we will erode free will gradually the more we successfully see the brain as a predictable machine rather than a mystery.

My own sense is that "chaos" and butterfly effects explain a lot of human behavior. Our decisions are not regular like billiard-ball collisions; the causes of our decisions/thoughts/actions are disparate and depend on what someone said to me yesterday, whether a girl just smiled at me, whether the restaurant is more expensive than I thought, whether it is warm in here, whether the table is round or rectangular, etc.

So prediction may always remain difficult merely because most decisions are "random-seeming" in the way that tornado formation is random-seeming. Not uncaused, but disparately and complicatedly caused in a way tough to fully unravel.

lung is not made out of

lung is not made out of atoms. so lung could never be predicted.

lung will eat your supercomputer! supercomputers are crunchy.

lung

The Dartmouth Flap

Have you heard about the flap at Dartmouth?:

Often it seems as though American higher education exists only to provide gag material for the outside world. The latest spectacle is an Ivy League professor threatening to sue her students...Priya Venkatesan taught English at Dartmouth College. She maintains that some of her students were so unreceptive of “French narrative theory” that it amounted to a hostile working environment. ...Ms. Venkatesan’s scholarly specialty is "science studies," which, as she wrote in a journal article last year, "teaches that scientific knowledge has suspect access to truth." She continues: "Scientific facts do not correspond to a natural reality but conform to a social construct."

After a winter of discontent, the snapping point came while Ms. Venkatesan was lecturing on "ecofeminism," which holds, in part, that scientific advancements benefit the patriarchy but leave women out. One student took issue, and reasonably so – actually, empirically so.... Following what she calls the student’s "diatribe," several of his classmates applauded. Ms. Venkatesan informed her pupils that their behavior was "fascist demagoguery."

When I first read this story I felt a little pang of guilt, since anybody familiar with my book The Slightest Philosophy knows that its stated purpose is to encourage and facilitate precisely this kind of student rebellion against precisely this kind of postmodern philosophy, and professors like Venkatesan are obviously targeted. I was almost afraid it would turn out one of the students had read it. I feel bad for the distress of the professor; I read an interview with her that led me to believe she's probably not born in the US, and so understandably may be having trouble dealing with our culture of insubordination.

But that doesn't change the fact that the postmodern philosophy she promotes is far more akin to fascism, both historically and logically, than the realism of her students is. In other words, I'm squarely on the side of the students, and have been in their place myself.

She grew up in upstate New