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Rationally Speaking is a blog maintained by Prof. Massimo Pigliucci, a philosopher at the City University of New York. The blog reflects the Enlightenment figure Marquis de Condorcet's idea of what a public intellectual (yes, we know, that's such a bad word) ought to be: someone who devotes himself to "the tracking down of prejudices in the hiding places where priests, the schools, the government, and all long-established institutions had gathered and protected them." You're welcome. Please notice that the contents of this blog can be reprinted under the standard Creative Commons license.

Tuesday, July 29, 2008

The zombification of philosophy (of mind)

David Chalmers is a famous philosopher of mind. His fame rests in great part on his 1996 book, The Conscious Mind: In Search of a Fundamental Theory. It’s too bad that the crucial idea behind the book, dualism, is hopelessly flawed, and -- more surprising yet -- that Chalmers got away with one of the most idiotic thought experiments ever, which a lot of people inexplicably seem to think is oh so very clever. This all came back to (my) mind because of a recent article in Philosophy Now by Rebecca Hanrahan (an assistant professor of philosophy at Whitman College in Washington state), who’s finally got the chutzpah to point out the obvious, telling it like it is about Chalmers’ famous “zombie argument.”

Let us start by recalling what dualism is: in philosophy the idea traces back at least to Descartes (though some would consider Plato a dualist), and his contention that while everything else in humans and animals is “mechanical” (i.e., made of matter), the mind is an exception, since it’s made of some kind of distinct mind stuff (he was pretty vague about exactly what this mind stuff might be, and so is Chalmers, incidentally). Descartes immediately got into trouble because he couldn’t provide an account of how is it that the non-material mind seems to interact so well with the physical world and have tangible effects (that’s what happens every time, say, you make up your “mind” of wanting a martini, and your body responds by walking you to the bar and starting the shaking of spirits and the piling of olives).

Descartes then famously dug himself even deeper into an intellectual quagmire when he proposed that the place where (somehow) mind stuff and body stuff “meet” is the pineal gland, at the center of the brain. Turns out that we now know that the pineal gland is actually involved in the production of melatonin which, while important in keeping the day/night cycle straight (it helps with jet lag), and likely relevant to normal sexuality (the gland is larger in children, where it inhibits sexual development) is far from the seat of the soul. If it were, most of us would be in trouble because in many adults the gland calcifies, becoming essentially non functional.

Back to Chalmers. He claimed to have revived dualism -- despite the generally bad reputation the word has even among philosophers -- and developed the following argument in support of his startling conclusion (this is Hanrahan’s, I think fair, formalization of if):

premise 1: We can conceive of a world populated by some zombie twins, who act exactly as we do, have our same physiology and internal structure, our brain and our psychology. But they do not have any conscious experience whatsoever.


premise 2: Conceivability provides us with a guide to possibility.

premise 3: It is possible that there is a world populated by our zombie twins.

conclusion 1: If this is possible, then materialism [the idea that everything is made of matter/energy] is false.

conclusion 2: If materialism is false, then dualism is true.

QED (Quod Erat Demonstrandum, as we wished to demonstrate)

I refer you to Hanrahan’s short and eminently digestible article for the details, but you can easily see that even if one of the stated premises is not true, then none of the conclusions will follow. Now, let’s take a look at the three premises, beginning with the last one, p3.

I suppose that it is possible that there may be living beings that are made like us but do not have conscious experiences, although they would be really strange beings. I find that possibility to be extremely unlikely, but I don’t see that it contradicts any known physical or logical law. p1 is also true: we can indeed conceive of the kind of zombies that Chalmers imagines, though it must be noted that these are not the lively flesh-eating chaps we see in the movies.

The real problem, of course, is with p2: conceivability is not a reliable guide to possibility. I can conceive of impossible things, such as the idea of squaring the circle, or of a god that is omnipotent and yet can make a mountain so big that she couldn’t move it, and so on. Chalmers comes up with an (admittedly ingenious) little story, and we are supposed to deduce from it the momentous conclusion that there is more than matter/energy to the universe? When things appear to be too good to be true there is often good reason to think that they in fact are too good to be true.

Moreover, although this is an unstated implication of the above deduction, possibility in turn is not a particularly good guide to reality. There are plenty of things that are possible but that are not in fact realized in the actual world. Remember that the question that Chalmers wishes to answer is whether human mental experience is compatible with materialism, as is strongly suggested by the fact that nobody has ever seen a mental state occur independently of the presence of a physical brain (what some philosophers call the “no ectoplasm clause”). While I think it is very reasonable to assume that anything that is real must also be possible (either that or our logic is seriously faulty), it is just bizarre to suggest that one can go from possibility to claims about reality, the way Chalmers does. Has he not learned anything from the failure of the rationalist program in philosophy?

Incidentally, I would note that mine (or Hanrahan’s, from what I can tell) is not an argument against thought experiments in general. They can be useful to evaluate our intuitions, and -- contrary to popular belief -- they are not just something that “armchair philosophers” (a redundant phrase if there ever was one) engage in. Scientists from Galileo to Einstein have used thought experiments to sharpen their thinking about the world. But just like any tool, it needs to be used according to reasonable instructions and to solve the appropriate problems, just because all you’ve got is a hammer that doesn’t turn everything into a nail.

As readers of this blog know, I am a scientist with a background in philosophy, and am very sympathetic to the whole philosophical approach to things. But just in the same way I think a lot of scientists do a disservice to themselves and to the public by not taking philosophy seriously, I am also convinced that people like Chalmers don’t help philosophy even a bit, either among scientists or the public. Let’s relegate zombies to B-movies and try to be a little more serious about our philosophy, shall we?

39 comments:


  1. Let’s relegate zombies to B-movies and try to be a little more serious about our philosophy, shall we?


    The fact that the argument concerning p-zombies that you address here is a bad one doesn't mean that p-zombie thought experiments aren't worth exploring. I don't see anything in what you've said that justifies the above conclusion.

    As to the argument itself, I don't know how well it reflects Chalmers position but I see another problem with it that I didn't see you mention:

    The conclusion no. 2:


    If materialism is false, then dualism is true.


    is obviously false. These are not the only options. Panpsychism, for example, could be true if materialism is false.

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  2. Perhaps Chalmers would consider vacationing with St. Anselm at that charming beachfront resort I hear they're building on Gaunilo's island? ;)

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  3. David,

    yes, I meant to point out the problem with conclusion 2 also, but ended up not including it in the post.

    On the other hand, I have a hard time thinking about what one could possibly gain by this sort of experiments if you agree that conceivability is no reliable guide to possibility.

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  4. I believe that Chalmers stated somewhere that the case for pan-psychism was actually a lot stronger than usually thought.

    So it seems that he has envisaged that possibility. Of course this raises problems of its own. It is easy to imagine what the psychic dimension for the brain would be like, since we merely refer to our own experience. But what about chimpanzees, bats, single cells, molecules, etc. IN fact, in the last analysis can one make any real sense of the idea?

    Of course, there is always a difference between the objective and the subjective. Dualism could be true, but trivially true.

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  5. John Searles had a good critique of Chalmers, which was included in his colletion, The Mystery of Consciousness...

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  6. There are also a lot of lousy arguments with the opposite of proposition 2- that inconceivability is a guide to possibility. Many creationists seem to think that the fact that they can't conceive of something makes it impossible.

    On zombies, I think Daniel Dennett makes decent use of the concept, at least in showing that if zombies exist, then they must have all the same internal states as conscious beings. If so, just what is the difference?

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  7. I've always found this argument ridiculous. I can conceive of a 747 that can fly without its XJ389-unit, because I have no idea how a 747 works or what an XJ389-unit is, or even if such a thing exists. Likewise, we don't know how the brain works and we don't know what consciousness is. I can't believe he's gotten away with conflating conception and possibility all these years.

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  8. Let’s relegate zombies to B-movies and try to be a little more serious about our philosophy, shall we?

    Thankfully, serious philosophy certainly doesn't preclude having a sense of humor.

    I find [the possibility of p-zombies] to be extremely unlikely, but I don’t see that it contradicts any known physical or logical law.

    In that case, what's so unlikely about it?

    I think the point of the p-zombie argument is that if we can conceive of p-zombies then what's the subjective experience of consciousness all about? Our brains can orchestrate our bodies' physiological functions, and perform a whole range of cognitive (computational?) functions. But why do we experience any of this? We have built machines that outperform us in certain types of computations. Are they conscious? Why (not)?

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  9. Nick,

    "I think the point of the p-zombie argument is that if we can conceive of p-zombies then what's the subjective experience of consciousness all about?"

    The point of the post is that the fact that we can conceive something tells us precisely nothing about whether that something is true or not (see another comment's example of conceiving of an airplane without a crucial component: we can conceive it, but the airplane isn't gonna fly).

    Hence, Chalmers' zombies have no relevance for our understanding of consciousness, and I'm still baffled by the fact that the guy got away with such spectacular nonsense for this long.

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  10. I don't see how that argument gets past premise 1.

    If zombie twins have the same physiology, internal structure, brain, and psychology as us, they would have the same minds as us, unless dualism is true. Thus, conceiving of zombie twins without minds amounts to simply conceiving that dualism is true.

    In other words, the argument begs the question, does it not?

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  11. Yes, it does seem like premise 1 implicitly begs the question. Is there no end to problems with Chalmers' so called argument??

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  12. Like qetzal (above), I've always seen this argument as dangerously close to an outright vicious circle. When we conceive of a world where there are these creatures who are EXACTLY (molecule for molecule, in every detail) our twins and yet somehow lack conscious experience (or qualia, or whatever nuances one chooses), we are quite simply conceiving of a world in which dualism is true: The zombie twins are physically identical yet experientially non-identical, which is the relevant feature of dualism in this argument.

    In essence, the argument starts with "Imagine my conclusion is true" and miraculously concludes with "My conclusion is true" - which is suspicious, but not actually circular by strict criteria. The real logical problem here is a bit better hidden. Let's look at the form of the argument stripped of the content:

    Premise 1 We can conceive of X. (X need not be zombies: X can simply be dualism, since the zombie case is just a way of stating dualism.)

    Premise 2 Conceivability provides us with a guide to possibility.

    Premise 3 From 1 & 2, X is possible.

    Premise 4 If X is possible, then any position which excludes the possibility of X is false.

    Conclusion 1 Position A (materialism) excludes the possibility of X, and therefore A is false (from 3 & 4).

    Conclusion 2 Since A is false (from Conclusion 1), X must be true.

    As David Ellis pointed out in the first comment, Conclusion 2 isn't warranted because it assumes (falsely, in this case) that the opposing claims are both mutually exclusive and exhaustive (i.e. they comprise all the possible positions). While dualism and materialism are mutually exclusive, they aren't the only possibilities. But frankly, I consider this a minor weakness of the argument - the other options are even less plausible than dualism, and the argument has much bigger problems before that step is even reached.

    Unlike Massimo, I don't think premise 2 is necessarily problematic: The examples of square circles and God paradoxes are actually classic examples of logical impossibilities, and depending on how one interprets "conceivable," I can see someone claiming that such things are not really conceivable. The real problem here is that conceivability can only be a guide to logical possibility, and can't really tell us one way or another anything about actual, concrete physical possibility. Something like dualism may be logically possible - that is, the very definition of dualism doesn't seem to contain any internal paradoxes or necessary contradictions - but that does not mean that it can actually be realized under the constraints of nature.

    Recognizing the difference between logical (or conceptual) possibility and physical possibility - rather than eliding the difference, as Chalmers seems to in every version of the zombie argument I've ever seen - premise 4 is revealed for sneaky fallacy of equivocation. Re-writing it with the properly delimited terms highlighted makes it obvious why the premise is ludicrous:

    4 If [conclusion] is logically possible, then any position which excludes the physical possibility of [conclusion] is false.

    Uhm, no. Many things are logically possible but not physically possible. Everything that is physically possible must also be logically possible, but it doesn't work the other way - as would be required for this premise to be true.

    Massimo made essentially the same criticism when he said "the fact that we can conceive something tells us precisely nothing about whether that something is true or not" and variations thereon. But I think it's worth the effort to work through the details. An analysis which exposes a blatant logical fallacy is a lot harder to wiggle out of than a generally stated conceptual criticism.

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  13. Thinkmonkey, I found your comment very lucid. But I wonder about this:

    The real problem here is that conceivability can only be a guide to logical possibility, and can't really tell us one way or another anything about actual, concrete physical possibility.

    We're talking about subjective conscious experience, so where does physical possibility come in? The trouble is we have no way of physically characterizing (or measuring) consciousness, only its neurological correlates. Consciousness is certainly actual but I find it hard to see it as concrete.

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  14. Hmm. I'm not immediately sure I see your point, Nick. I don't know where physical possibility comes in; I'm not the one who illegitimately smuggled it into the argument via equivocation, Chalmers is. My only claim is that sitting and thinking can only give one insight into logical possibility, not physical possibility.

    Logical possibility is rather clearly and strictly defined: Typically, if there is no outright violation of the law of non-contradiction embedded in claims about the existence of an object or state of affairs, then it is logically possible. Consider the invisible pink unicorn: Because it by definition both has a color (reflects some light) and does not have a color (because it wouldn't be invisible if it reflected light), its existence is impossible. Now consider a very simplified statement of dualism: Consciousness is "more than" brain activity. (Otherwise zombies, which by hypothesis are identical and so must have identical brain activity, could not lack consciousness.) Is there any logical contradiction involved in any reasonable interpretation or definition of those terms? Doesn't seem to be. So, dualism is logically possible.

    I'll warrant that evaluating physical possibility is much more complicated: It requires figuring out what regularities, patterns and limitations are involved in what is physically actual - that is, understanding objects, events and processes in the world around us - and inferring what other objects, events and processes are consistent with those regularities, etc. In other words, evaluating physical possibility at the very least requires some investigation in and engagement with the world, whereas logical possibility can be addressed by imagination and analysis alone.

    Chalmers' zombie thought experiment completely ignores engagement with the world, to a rather radical degree. His proposed "possibility" posits identical causes having different effects: You cannot simply assert the physical possibility of something which contradicts all of our collective and collected experiences of the world and its operations, although it is certainly logically possible. Ergo, Chalmers' use of the term "possible" about zombies really must mean "logically possible." If he meant "physically possible," the claim is wildly implausible on the face of it, and he gives no argument that makes it more plausible in physical terms.

    These claims about dualism and materialism, or even the specific claims about the possibility of zombies identical to us in every way except that they lack qualitative aspects of conscious experience (or whatever), are claims about the world (the realm of physical possibility) and not just claims about the relation of concepts to other concepts (the realm of logical possibility). If someone wants to make claims about the real world, they're gonna have to get out of that armchair eventually.

    Your other point, about consciousness not being concrete, speaks to the very broad and obvious problem with proposing dualism as a solution to the "hard problem" of consciousness. Tell Phineas Gage - or any of the many, many millions of other people whose consciousness was altered in some respect or another by physical injury to the brain - that consciousness isn't concrete and physical.

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  15. I'm confused. Did Chalmers specifically state that his zombies are physically the same as us, or just that they behave as we do?

    In the first case, Data on Star Trek TNG could not be a zombie, in the second , he could. Dr. Pulaski's insistence that Data was not truly conscious, but merely mimics consciousness, reflects her commitment to dualism, as well as an insistence that only organic beings could have an immaterial aspect of their consciousness.

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  16. Thinkmonkey, thanks for your reply. You write:

    You cannot simply assert the physical possibility of something which contradicts all of our collective and collected experiences of the world and its operations, although it is certainly logically possible.

    But ultimately each of us can only really be sure of our own consciousness (this is how I interpret Descartes' "I think therefore I am"). A zombie would behave as if it had an inner life, and thereby seem to corroborate our "collective and collected experiences of the world". I don't believe this—who really does?—but to me it suggests that consciousness is something entirely unique.

    If you're interested, check out my blog posts on issues relating to consciousness.

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  17. Conceivabiliy is not a reliable guide to possibility. Any idea which can be expressed, including impossible ones, has been conceived.
    Lack of logical inconsistencies is one guide to possibility, as is consistency with empirical physical observation.

    Descarte's "I think, therefore I am" convinces me that I experience consciousness, but I cannot apply this test to anyone else. I have not yet thought of any way to confirm consciousness in anyone or anything except myself.

    This problem comes up in Artificial Intelligence. How do we know when we've created a conscious computer? It strikes me as an impossible thing to test.
    Interestingly, it seems to me we are a lot better off if our computers are zombies. If we did succeed in creating a computer that was conscious, we would then be ethically compelled to help it achieve happiness.
    For example, if we simulated every particle in a human being and his or her immediate environment, this human being would show symptoms of all human emotions, including survival instinct. The damn thing would be begging us not to shut the computer off.

    Conversely, if zombies do exist and some accurate test were determined that could identify them as such, they could be very useful to us in the we could exploit of enslave them without any moral qualms, or use them in medical experiments.

    I've read that psychologists think that at least 5% of males (I have no data for females) are psychopaths. Perhaps they are people who think the rest of the human race are zombies.

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  18. I wonder if Chalmers is familiar with Hume's Dictum? If a person is stating that because something can be conceived it must be possible to exist, that is one thing. However, that doesn't mean it exists until the evidence of such is put forth. As Hume would say, a relation of idea is only supported by that exact entity within its realm, and if one did put forth concrete - material - evidence to support it, the concept would change realms.

    Thus unicorns and zombies exist by whatever abstract line of thinking you want to use to present them. If, however, concrete evidence came forth for the existence of such creatures, they would become concrete concepts, no longer abstract.

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  19. "I've read that psychologists think that at least 5% of males are psychopaths. Perhaps they are people who think the rest of the human race are zombies"

    Or THEY are the soulless zombies. :)

    I strongly believe in dualism for this reason: it feels true to me. That isn't scientific, I admit, but almost every culture in the world has a history of beilief in a world beyond the physical.

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  20. "Uhm, no. Many things are logically possible but not physically possible. Everything that is physically possible must also be logically possible, but it doesn't work the other way - as would be required for this premise to be true."

    Is that really true, though? Not only is it physically possible to have a subatomic particle create an interference pattern by interfering with itself, but also on the smallest scales possible, we see tons of contradictions and ridiculous conclusions. Maybe I'm missing something important though - does using "logic" here imply situations where we know it applies, i.e. the relatively large physical world?

    In unrelated news, there is a great argument over at Stephen Law's blog. I think everyone here would love it, and he'd love to have help, I'm sure.

    http://stephenlaw.blogspot.com

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  21. Kosmo,


    "That isn't scientific, I admit, but almost every culture in the world has a history of beilief in a world beyond the physical."

    I am curious, why you believe in something that has not a rational support, in your statement apparently you are completely aware of that. Just for deference to public opinion? (...every culture in the world has a history of beilief in...)

    cheers.
    ICARO

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  22. That isn't scientific, I admit, but almost every culture in the world has a history of beilief in a world beyond the physical.


    And, of course, we know of no beliefs most of humanity has held that turned out to be false.....

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  23. A book recommendation for anyone interested in p-zombies (and philosophy of mind in general):

    BLINDSIGHT by Peter Watts.

    Its a science fiction novel (and nominee for the 2007 Hugo award) about humanity's first contact with an alien intelligence---a species which turns out, despite being vastly smarter than us, to be nonconscious.

    Terrific book, if you like philosophically inclined science fiction.

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  24. Unfortunately it seems to me that your criticism of Chalmer’s arguments are nonsensical from start to finish.

    I guess by “mind stuff” you mean mental substance. But Chalmer’s does not believe in the existence of mental substance. So the first 3 paragraphs are simply an irrelevance.

    Reading further on, and in regards to premise 1 you state:

    “I suppose that it is possible that there may be living beings that are made like us but do not have conscious experiences, although they would be really strange beings. I find that possibility to be extremely unlikely, but I don’t see that it contradicts any known physical or logical law”.


    If it is logically possible that there are beings who exactly physically resemble us except they have no inner mental life, then this is a straightforward denial of materialism. Materialism stipulates that physical facts *entail* mental facts. So if materialism is true then it is *logically impossible* for there to be beings who are made of the same type of stuff as us, and who are constructed identically to us, but yet lack any conscious experiences.

    Of course presumably such beings are physically impossible. But logically impossible?? But no need to pursue this point at this juncture since you seem to agree with this.

    You state:

    “The real problem, of course, is with p2: conceivability is not a reliable guide to possibility. I can conceive of impossible things, such as the idea of squaring the circle, or of a god that is omnipotent and yet can make a mountain so big that she couldn’t move it, and so on”.

    Here you are asserting that you can conceive of something being true, but which, by the very meaning of the words, is false!. If someone states they can conceive of a married bachelor, then they are simply failing to understand what the word bachelor means. The same goes for a square circle, or an omnipotent God which is not omnipotent. These are false by the very meaning of the words we are employing.

    The above examples are entirely different from saying it is conceivable there are beings who exactly resemble us apart from an inner mental life. This is at least conceivable unlike a married bachelor or a square circle.

    Now the crucial question here is whether conceivability implies logical possibility. It seems to me it does, and that therefore materialism is necessarily false. But even if you disagree with me that such beings are logically possible, the onus is upon you to explain what is logically incoherent about such beings? Unless you can provide any hint of an answer, then our default position must surely be that materialism is false.

    You state:
    “Moreover, although this is an unstated implication of the above deduction, possibility in turn is not a particularly good guide to reality. There are plenty of things that are possible but that are not in fact realized in the actual world”.

    This is completely irrelevant. We are not talking about physical possibility.

    You state:

    “Remember that the question that Chalmers wishes to answer is whether human mental experience is compatible with materialism, as is strongly suggested by the fact that nobody has ever seen a mental state occur independently of the presence of a physical brain”.

    This is question begging of the worst kind. If we could see, or at least physically detect, a mental state occur independently of the presence of a physical brain, then by definition that mental state would be physical. But those who reject materialism do not believe that mental states are physical. Thus dualism entails that we will not be able to physically detect a mental state occur independently of the presence of a physical brain!

    But this is all by the by since Chalmer’s holds that mental states are ontologically dependent on brain states. Thus since Chalmer’s position is that brains *create* mental states, it cannot be a criticism of his position when you state that mental states cannot be detected in absence from a brain.

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  25. Ian,

    I'm afraid you are engaging in the same sort of sophistry that Chalmers likes so much, and which I maintain gives a bad reputation to philosophy:

    "But Chalmer’s does not believe in the existence of mental substance."

    Yes, that's what he says, but in what sense there can be dualism if there isn't some other stuff outside of physical stuff?

    "Materialism stipulates that physical facts *entail* mental facts."

    Says who? Materialism simply says that whatever exists must be made of matter/energy, so if mental phenomena are real, then they have to be grounded in matter/energy. You are conveniently reversing the logical order.

    "These are false by the very meaning of the words we are employing. ... it is conceivable there are beings who exactly resemble us apart from an inner mental life."

    I realize the distinction between a logical and a physical impossibility, but his example really blurs the distinction here: how does he know that his zombies are not logically impossible? Because he assumes dualism, as one of the other commenters pointed out, thereby begging the question.

    "the onus is upon you to explain what is logically incoherent about such beings."

    No the onus is on you and people like Chalmers, who are making extraordinary claims supported only by a bit of fuzzy language.

    "We are not talking about physical possibility."

    Maybe you are not, but to me that is the crucial question, since logical possibility isn't going to settle the matter.

    "those who reject materialism do not believe that mental states are physical. Thus dualism entails that we will not be able to physically detect a mental state occur independently of the presence of a physical brain!"

    Do you even realize how silly this position is? Can't be defeated in principle, can it? And you call this good philosophy? A incredible castle built on thin air is what I call it.

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  26. Ian said,

    "those who reject materialism do not believe that mental states are physical. Thus dualism entails that we will not be able to physically detect a mental state occur independently of the presence of a physical brain!"

    Massimo replied,

    "Do you even realize how silly this position is? Can't be defeated in principle, can it? And you call this good philosophy? A incredible castle built on thin air is what I call it."


    Massimo, if Ian's statement is so silly, it should have been no problem to point out why. Or is Ian, in fact, correct and your series of rhetorical questions are just an expression of frustration?

    If mental states are not physical, why would we expect to be able to use physical detection as a means of knowing about them?

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  27. Thus dualism entails that we will not be able to physically detect a mental state occur independently of the presence of a physical brain!

    But you should be able to report a mental state that occurs independently of the brain.

    That is getting increasingly difficult to do.

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  28. Dave,

    perhaps silly is not the best word, but we are presented with a notion that is a) empirically impossible to verify; b) logically inconsistent; c) based on the obviously dubious assertion that conceivability is a reliable guide to possibility and in turn reality.

    If it ain't silly, it certainly makes for very bad philosophy, methinks.

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  29. Is empirical verification a necessary requirement of a philosophical argument? It may be necessary for a scientific theory but I thought we talking philosophy here?

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  30. Dave,

    no, empirical verification is not necessary for a philosophical argument (though philosophy is at its best, I think, when it takes empirical evidence seriously, which I don't think Chalmers does).

    However, when an argument lacks both empirical verification and logical coherence, and/or is based on arbitrary and highly questionable assumptions, one begins to wander what sort of activity one is engaging in. Not good philosophy, I should think.

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  31. Ivan wrote: "I am curious, why you believe in something that has not a rational support."

    It is nothing so blind as faith. Dualism feels true to me for the same reason that Zen Buddhism feels true: it matches up nicely with the scientific evidence in a way that rises above mere logic and rationality—without ever contradicting them—and is itself beautiful. Everywhere you look, the world is circles within circles, the same processes and patterns repeated again and again—a beauty and symetry that is found in the natural world and mirrored in mathematics and physics. Mathematicians talk about formulas that are elegant. Truth often has an aesthetic beauty you can recognize without understanding why.

    Feynman' two-slit experiment requires an observer to collapse the probability wave-function. Is that observer found in the retinal rod-rhodospin molecules of the retina? No, it is in the mind of the observer. The consciousness. Why would this be? Point a dead man’s eyes at the double-slit experiment, and what will you get?

    David wrote: And, of course, we know of no beliefs most of humanity has held that turned out to be false.....

    David, I get the sarcasm and agree with you. Many of the beliefs humanity has held have turned out to be false. But the more universal something is, the more seriously, I think, it needs to be looked at. The question becomes, why does every culture believe this? Even that wouldn’t convince me though, I admit. It was the study of physics that finally made me believe. Quantum mechanics and Buddhism are like different translations of the same parent text. If there is a Truth with a capitol letter, there should be more than one path to reaching it. At least that's how I feel.

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  32. For me, the best thing out of this discussion is actually the Zombie Food Pyramid. I'll do my best to follow it, but won't promise anything. Not very disciplined when it comes to edible stuff, y'know.

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  33. I'll sound like a panpsycic - but I think the question of why we have consciousness is arse backwards. the question is if there is a situation where more or less the same processes occur as in our mind, except outside of it, why is it that that process would NOT have a subjective experience?
    the obvious answer is that there is no reason. and the conclusion is that subjective experiences are not unique to humans even if complex (and interesting) subjective experiences are.

    I.e. that having the equations that are a thought and having a thought are completely inseparable. And to say that you could have the equations that are a thought without actually having that thought is like saying you could have an arm without having an arm. Completely inconceivable if you aren't confused.

    > Feynman' two-slit experiment requires an observer to collapse the probability wave-function. Is that observer found in the retinal rod-rhodospin molecules of the retina?

    BTW, you've made a empirical mistake it IS in the rods. the rods will collapse the wave function before it reaches the brain. That could be demonstrated experimentally.

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  34. What do you make of the philosopher, Ken Wilber? Would love to read a blog post from you about his ideas, debunking them or supporting them or anything in between.

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  35. I'm a phenomenological anthropologist and not a philosopher. But even reading this post and skimming Hanrahan's article makes me wonder how did David Chalmers ever get to become so famous with his flawed thinking?

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  36. I think that the idea for the zombie problem comes from Kripke's "Naming and Necessity," where he suggests that conceivabilitly tells us something. Here is how I interpret the zombie problem:

    Let's say that you have two statements:

    (1) Mental processes and consciousness are the same thing.
    (2) I can imagine a zombie.

    Conceivability is a test to see if something is internally contradictory. I can conceive of a ball that accelerates without being acted upon, because it breaks the rules of the universe without being a contradiction itself. However, I cannot conceive of a cup that has water but not H2O, because that is internally contradictory (it can be formulated by the statement P & not P).
    If mental processes are the same as consciousness, then the zombie having mental processes without consciousness should be formulated as P and not P, a contradiction, and therefore be difficult to conceive of like a cup with water but without H2O. Instead, I find zombies easy to imagine, like a ball that accelerates without being acted upon. Therefore, mental processes and consciousness are not the same thing.

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    1. I forgot to mention, the end result is that the two statements I gave are inconsistent with one another.

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  37. Chalmers himself addresses this in a paper (published six years before this post) entitled 'Does Concievability Imply Possibility?' It's available for free on his website here, http://consc.net/papers/conceivability.html

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    1. Todd,

      yes, but there is a difference between having "addressed" the issue and having given a plausible answer. I don't think Chalmers did. And I'm far from being the only philosopher who thinks so. (Note also that the paper in question was not published in a peer reviewed journal, but only in an edited collection of essays.)

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