Monday, April 21, 2008

Zombie Review

Bring out your [un]dead! After all my narrowly focused posts on the topic, it's time for a "big picture" review of the zombie argument against physicalism. Recall: Physicalists think that the physical facts exhaust the base facts: just as the arrangement of particles suffices to settle whether there are tables, so it suffices to settle whether there is conscious experience. So let 'P' denote their complete microphysical description of the world, which makes no explicit reference to phenomenal experience or qualia. Let 'Q' be a statement explicitly about my qualia. The classic argument for dualism thus follows:
1. (P & ~Q) is ideally conceivable [can't be ruled out a priori]
2. If (P & ~Q) is ideally conceivable then (P & ~Q) is possible.
3. If (P & ~Q) is possible then physicalism is false.
Therefore, physicalism is false.

(3) is analytic: if you can have P without Q, then P does not suffice for Q, contrary to the physicalist's claims.

(2) is the premise most philosophers [as "type B materialists"] have traditionally questioned. It raises complicated issues in the metaphysics of modality and philosophy of language which I addressed in depth for my ANU honours thesis: 'Modal Rationalism'. (But you can get the short version here.) The upshot is that denying this step is ad hoc and ultimately commits you to the unmotivated claim that there are coherent scenarios which do not correspond to any possible world. I won't address it further here.

The blogospheric discussion has instead focused on premise (1). I think the intuitive force of the premise is made especially vivid by the zombie thought-experiment, whereby we imagine a world physically like ours but lacking in consciousness. That sure seems conceivable, but type-A materialists are committed to denying this, and claiming instead that there is some implicit contradiction which renders the zombie scenario incoherent. Unfortunately, nobody seems to have any idea what this elusive contradiction might be. (Unless you count Eliezer's suggestion, but that was based on a demonstrably false premise in the philosophy of language.)

Brandon made the reasonable point that we're not in a position to assess (1) with total confidence because we don't yet know what the statement P of completed microphysics says. That's a fair point; I certainly don't think this is a knock-down argument. But we do the best we can from our position of uncertainty, and it seems to me that we have more reason to believe (1) than its negation. So we should lean more towards property dualism, pending further evidence.

Some of the other objections that have been raised are, I think, simply confused. For example, Tanasije worries that epiphenomenalists will have no high-level explanation of our 'consciousness'-related behaviour (e.g. my writing this blog post). But we have no fewer resources than the physicalist, we just use different words to describe them. So while I would deny that zombies have beliefs about consciousness, there is a functionalist analogue (or physical component) of belief, which we may call 'z-belief', which can be cited by third parties and will do all the same scientific/explanatory work. (This raises more interesting worries about whether zombie brains are somehow 'malfunctioning' by z-believing in consciousness, which I address in my post: Zombie Rationality.)

Then there's Richard Brown's attempt at constructing an analogous "non-physical zombie" argument (replacing 'P' with 'NP' above) against dualism. But that won't work for the following reason: (i) Either 'NP' explicitly states the qualia facts Q, or it does not. (ii) If it does, then (NP & ~Q) is straightforwardly contradictory, so the first premise fails. (iii) Otherwise, the third premise fails. The possibility of (NP & ~Q) is compatible with dualism, because the dualist never claimed that those other non-physical facts NP suffice for consciousness. So, either way, it's a terrible argument.

Conclusion

As noted in my original post on the current blogospheric dispute, there are some bullets to bite either way.

The [type-A] materialist must simply have faith that there is an implicit contradiction somewhere in the zombie scenario, even though it shows no sign of such incoherence. They must also trust that third-personal scientific inquiry into non-experiential facts will somehow turn out to imply first-personal experiential facts in the same way that it implies the facts about ordinary macro objects like tables and chairs.

The epiphenomenalist, on the other hand, must explain how we can know that we're conscious if it has no causal effect. This will naturally lead to certain views about belief content and epistemology that others might balk at.

I don't think it's obvious how to weigh these various considerations. Personally, I lean towards epiphenomenalism -- the implications don't strike me as particularly worrisome. But your mileage may vary.

[There are also other views [PDF] on the table, e.g. interactionist dualism and panprotopsychism, but I won't address them here.]

P.S. Don't miss the zombie song - 're: your brains' [ht: Chris].

50 comments:

  1. My position: I'm a skeptic on (1) and (2), in the sense that I don't think I have any idea whether they're true. The notion of "conceivability" bothers me, but I'll work with your definition of "can't be ruled out a priori."

    That can be read as 1', that this is true as a contingent fact about our cognitive capacities, or 1'', that it's true in principle, with any cognitive capacities. On 1', the corresponding 2' is unmotivated, as there's no reason to give such force to contingent facts about psychology. On 1'', we just have no idea, because the fact that we seem to be able to imagine it is no argument that it would be impossible for the most ideal thinker to rule it out a priori.

    On 2'', the question of whether there are necessary truths (restrictions on possibility) that can't be demonstrated a priori is so arcane I simply don't understand how anyone can be confident about it. Neither answer seems to underly any key common-sense belief about the world, so I'm agnostic.

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  2. Thanks, I've updated my post to read "ideally conceivable", to make that clearer.

    N.B. I'd say the persisting inability of anyone to discern any contradiction in a scenario is surely defeasible evidence that there's none there to be found. Otherwise you end up with a kind of radical modal skepticism -- you can't even say whether it's logically possible that I be standing up now rather than sitting, since "the fact that we seem to be able to imagine it is no argument that it would be impossible for the most ideal thinker to rule it out a priori." That just seems kind of silly. Also, it would rule out a lot more philosophy than just these anti-physicalist arguments. Modal arguments are ubiquitous. So we shouldn't be in too much of a rush to throw away all claims to modal knowledge. That is too much like throwing away all inductive knowledge merely because it happens to be defeasible.

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  3. By the way, for anyone interested in modal epistemology, I recommend Yablo's paper:

    Yablo, S. (1993) ‘Is Conceivability a Guide to Possibility?’ Philosophy and Phenomenological Research 53: 1-42.

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  4. It's possible to be a modal skeptic about claims far removed from ordinary experience, while accepting common-sense modal claims. Though I don't know a great deal about this debate, Peter van Inwagen has defended roughly that position.

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  5. Has Eliezer surrendered regarding the understanding of language as it relates to this sort of thing?
    If so that is quite a victory.

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  6. I think it would probably be most productive to present the zombie argument (and similar arguments) in a less evangelical manner.

    What happens usually with these debates is that people run off trying to prove that qualia don't have effects or similar.

    so instead you could put up a list of 'bullets' bitten to direct attacks to the right sorts of paces and highlight points of agreement which would be a waste of time to fight over.

    I am thinking something like
    1) you believe qualia have no effect on the universe (sure its said often but it needs repeating)
    2) you are OK with qualia being part of physical law just that they hold the special status of not being reducible to other laws and have the special one way cause/effect relationship above. (an additional law that ascribes a perspective (and therefore value) to a certain pattern. So fundamentally your non reductionist rather than 'dual[world]ist'.
    3) you tend towards believing qualia are points of data rather than 'a soul' in structure (as far as i can tell - souls are a common sort of assumption)
    4) you don't think your argument has causal justification. I.e. it is good because it happens to be true not that it was formed in a truth forming process.

    Of course that sort of debate enabling might be (or maybe not?) a little contrary to the 'selling of an idea' objective but one can evaluate the moral status of those two.

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  7. Eliezer has not surrendered on the language issue. Eliezer does not think Richard understands why Eliezer is talking about "the cause of my talk about 'consciousness'".

    It is not because of a general principle that words can only refer to the causes of their own invention.

    It is because, in this particular case, if "consciousness" does not refer to something that is among other things the cause of David Chalmers's philosophy papers, it is not clear what the hell the word "consciousness" could possibly mean. We are not talking about an artificially constructed concept like "unicorn" here. We're talking about a sense of inner awareness that seems very real to us, and that, in an intuitive sense, would obviously seem to make us write about "a sense of inner awareness".

    If you accept the above statement, it directly falsifies the zombie argument. You do not have to look hard for an unspecified contradiction. It is right there.

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  8. Hi Richard -

    thanks very much for the post. Exactly what I was looking for.

    Two areas then in which I still don't quite get your view:

    a) your above argument seems to rely on there being two positions - qualia exist and are non physical , or qualia don't exist (the Dennett position).

    But that surely leaves out the most plausible position - qualia exist and are a physical phenomenon (that we don't understand yet).

    It seems to me that you need to be making a strong argument that qualia *can't* be physical - is that what the Zombie argument is supposed to provide?

    Because intuitively to me, even if you accept the Zombie argument all it does is show that you could have a world without qualia, not that they are themselves non physical. What's the difference to imagining a world where everyone is colour blind, and thus proposing that colour is non physical?

    It seems to me that the reason most people believe qualia are non physical is just because it seems impossible, incomprehensible to us to come up with some sort of physical explanation for them, and so we assume that it is in fact impossible. Is that instead the argument you favour, rather than the Zombie thought experiment?

    b) The second point is what I was trying to get into in our last conversation on the topic : what is the epiphenomalist picture of how all this works? Qualia exist as non physical properties of our objects - but through what method or chain of causation do they cause our first person experience of them? Is that first person experience itself in my physical mind, or in a non physical soul?

    (I know you hate the soul word, so exchange for non physical mind if you prefer :) )

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  9. I'd say the persisting inability of anyone to discern any contradiction in a scenario is surely defeasible evidence that there's none there to be found.

    I'd say it's stronger evidence in simple everyday scenarios like standing rather than sitting, than in complex far-from-intuition scenarios like zombie world.

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  10. I'm with Eliezer on anti-epiphenomenalism. Also, on conceivability, I think The Princess Bride had a very valuable insight:

    Vizzini: HE DIDN'T FALL? INCONCEIVABLE.
    Inigo Montoya: You keep using that word. I do not think it means what you think it means.

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  11. While I'd made a comment about future physics maybe turning one to property dualism now that I think about it I'm not sure that's right.

    Let's say in some future description of reality a 1st person or quasi-1st person description is necessary. (It needn't be full minds - let's say it's something like Peirce calls a quasi-mind out of which our minds are a reductive emergent property)

    Now are the physicalists arguments open to this possibility? Further, if the physicalists assume something about physics methadology can their physics even accept such a thing?

    Of course the big problem is that scientific methadology is hardly a fixed entity - despite the overly simplified "scientific method" taught to kids. So it's quite reasonable to assume a future physics might accept a 1st person account. However isn't the physicalist position just the rejection of this?

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  12. To add to Richard's point. The strongest argument against physicalism is that given scientific descriptions and laws in the soft sciences there is no way to reduce them to physics.

    Now this is a semi-weak case since in regular biology this used to be the case as well. (Lots of teleological talk) However since the middle of the century a lot of folks have tried to make biological foundations more respectable and at least in theory reducible to physics.

    However there is a strong position in philosophy of science that the softer sciences are not even in principle reducible to physics. This isn't a statement about physicalism but rather a statement about the language used in such disciplines.

    Given this, why should we expect physicalism to be true?

    (The physicalist will obviously say that to be fully respectable biology, neurology, psychology and even economics will one day have to be reducible to physics)

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  13. Richard, I have grave misgivings about this argument. I'd want to know more about what exactly you mean by "ideally conceivable" and its relationship to possibility before I could tell you whether I'm denying premise (1) or premise (2), but when I read the whole thing, I get the unmistakable feeling that someone's trying to play a trick on me. (It's a similar feeling to the one I get when I read ontological proofs for the existence of God.)

    To illuminate what I think the trick is, let me give a parallel argument, which follows Richard's structure as closely as possible:

    (1) Perpetual motion machines are ideally conceivable.
    (2) If perpetual motion machines are ideally conceivable, then perpetual motion machines are possible.
    (3) If perpetual motion machines are possible, then the laws of thermodynamics are false.
    Therefore, the laws of thermodynamics are false.

    Is this or is this not the same logic? I can't see any problem with it. Surely, perpetual motion machines *are* ideally conceivable. I can't tell you exactly how to build it, but I can readily imagine a wonderful machine which, once it's powered up, begins spinning its flywheels and blinking its lights and ultimately producing vast quantities of free, clean energy from nowhere. Can we rule such a thing out a priori? Certainly not. And by Richard's logic, that must mean it's possible to build one. Look at that - I've just disproved the laws of thermodynamics without getting out of my armchair! Where's my Nobel Prize?

    Actually, I think writing this has helped me clarify my own thoughts, because now I know precisely what I object to about this argument. It's the illicit slide from "conceivable in the imagination" to "possible in reality", which commits equivocation between two very distinct definitions of "possible".

    We don't need to deny all of modal logic to conclude that, though certain things are possible simpliciter, those same things may not be possible in this world. There are, no doubt, possible worlds which contain perpetual motion machines. But this world, as best we can tell, is not one of them. In this world, perpetual motion machines are impossible. The governing principles of this world are arranged so as to exclude that possibility. Similarly, there are possible worlds where zombies can exist - i.e., where dualism is true and physicalism is false. But this world isn't one of them.

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  14. Adam - to clarify, the conclusion of the argument is not that there could be zombies in this world (see here). Rather, the claim is that there is some possible world containing zombies. This suffices to refute physicalism, because physicalism is a modal thesis: it claims that the physical stuff strictly suffices for consciousness -- i.e. it's metaphysically impossible to have (P & ~Q).

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  15. Richard - I'm puzzled what all the fuss is about, then. Of course there are possible worlds where zombies exist. Was that ever a point of contention? Who was seriously claiming that zombies are metaphysically impossible in every conceivable world? Frankly, that seems like a straw man to me.

    From the Stanford Encyclopedia of Philosophy:

    "The general idea is that the nature of the actual world (i.e. the universe and everything in it) conforms to a certain condition, the condition of being physical."

    I've always understood physicalism to be a claim about the properties of this world. I'll cheerfully grant that I can imagine a world where zombies exist. The idea is not self-refuting. But I really don't think that says anything meaningful about the way the world actually is.

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  16. Adam - I can assure you, it's no straw man. This is what the debate is about. Read the rest of your linked article:

    "Physicalism is true at a possible world w iff any world which is a minimal physical duplicate of w is a duplicate of w simpliciter"

    The zombie world is a physical duplicate of ours, but lacks consciousness. That tells you something about our world, namely that the physical stuff in it does not metaphysically suffice for consciousness. Something more is needed (e.g. the psycho-physical bridging laws that happen to hold in our universe).

    More generally, we can see that modal claims have actual import, since the necessity of identity implies that if two things can possibly come apart, they are actually distinct.

    P.S. I'm not sure exactly what you mean by "metaphysically impossible in every conceivable world". A proposition P is metaphysically impossible iff P is false in every metaphysically possible world. So your phrase is equivalent to "[false in every metaphysically possible world] in every conceivable world", which I don't think is what you meant to say. Some people dispute the relation between conceivable and metaphysically possible worlds, but we needn't get into that here. [See the links in my discussion of premise (2).]

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  17. Eliezer - "if "consciousness" does not refer to something that is among other things the cause of David Chalmers's philosophy papers, it is not clear what the hell the word "consciousness" could possibly mean."

    Funny, everyone else understands what I mean just fine. Now, it may be part of the folk theory of consciousness that it is involved in 'mental causation', and specifically causing us to talk about it. But I think this is very obviously not central to the word's meaning. The meaning of 'phenomenal consciousness' is given more directly by our intimate acquaintance with subjective experience itself.

    (Indeed, it's extremely easy to imagine scenarios in which consciousness does not cause Chalmers' philosophy papers. So that's clearly not essential to the meaning. But we should continue this discussion in the specific thread devoted to 'non-causal talk'.)

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  18. Nick - agreed, for more complex and unusual scenarios, our inability to discern any contradiction is weaker (but still) defeasible evidence that there's none to be found.

    Clark - "Let's say in some future description of reality a 1st person or quasi-1st person description is necessary... Now are the physicalists arguments open to this possibility?"

    Good question. I'm assuming that they deny this possibility (which sounds like Chalmers' 'type F' view, or 'panprotopsychism'). I have no objection to that view. But for terminological clarity, let's stipulate that 'physics' is essentially third-personal, as per our current understanding of it.

    "However there is a strong position in philosophy of science that the softer sciences are not even in principle reducible to physics. This isn't a statement about physicalism but rather a statement about the language used in such disciplines."

    I don't think the physicalist should be too worried about this. Forget language; what really matters is metaphysical supervenience (see my response to Adam above). Presumably any physical duplicate of our world will also have all the same economic truths. (There's no "economics-zombie" world!)

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  19. Adam,

    I presume you are proposing that reductionism is true here but not true elsewhere, i.e. it isn't 'necessary' in the same way as we might say 'bridging laws' are not necessary.

    It would probably be related to metaphysical skepticism because reductionism is a classic candidate for 'necessary status'. So it may be close to saying that you can't say anything much about necessary things and I imagine philosophers would be loathe to put themselves out of a job in such a way.

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  20. "The zombie world is a physical duplicate of ours, but lacks consciousness. That tells you something about our world, namely that the physical stuff in it does not metaphysically suffice for consciousness. Something more is needed (e.g. the psycho-physical bridging laws that happen to hold in our universe)."

    I'm not really up on this stuff, but a question: Does the "complete microphysical description of the world" include facts about laws of nature, and(/or) the dispositional properties of objects, or not?

    I wonder if some of the confusion here is arising over this question. If your definition of "all" the physical facts is more restrictive than some physicalists' definition of the same, then your assertion that the physical facts don't entail qualia might be consistent with their assertion that they do.

    (If this is the right way to frame the issue, then resolution might follow if one could resolve some of the metaphysical disputes over these questions: e.g. Are laws of nature physical? Are any properties non-dispositional? If not, can you specify anything about the physical world without reference to dispositional properties?

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  21. Alex - yeah, that's a helpful way to clarify the issue. I'm using "completed physics" to include physical laws of nature, but not the psycho-physical bridging laws that we posit to hold with the same 'nomic' necessity (and metaphysical contingency). A Type-F panprotopsychist might appeal instead to the categorical properties of things. In either case, we are going beyond 3rd personal physics. (Cf. my response to Clark above.) Of course, if someone wanted to grant me all these substantive points but redefine the term 'physicalist' to be compatible with taking experience as a new addition to the base facts of the world, I'm fine with that :-)

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  22. I'm getting more and more puzzled about this. Again, I can grant that a world which contained the same material objects in the same arrangement as our own, but which had different physical laws governing the way those objects behave, could contain zombies. Again, I can't see this as a point of contention.

    But if I'm understanding the argument correctly, you're saying that it's conceivable there's a world with the same objects and all the same laws of physics as our own, but that contained only zombies whereas our world contains conscious beings? Is that an accurate description of the claim being advanced here?

    If that's the claim, then no. No way, no how. A world which contained the same objects and the same laws of physics as our world would be our world. Whether there are "psycho-physical bridging laws" which do not reduce to the laws of physics is the very claim at issue here. You can't just assert that it's possible to hold everything else about our world constant, but subtract consciousness. That would be assuming what you wish to prove.

    Again, this strikes me as similar to my perpetual motion machine example. Certainly, some misguided philosopher could postulate a possible world which was exactly identical to our own, with all the same laws of physics, but without the "energy-entropy bridging laws" which forbid perpetual motion machines to work. Such a claim would fail to understand that the laws of physics are what prevent perpetual motion machines from functioning. That conclusion is already implicit in the working-out of those laws - it's not an additional, arbitrary principle that can be changed without changing the laws themselves.

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  23. Adam - right, the zombie world is stipulated to be just like ours in all purely physical respects (the physical stuff and the laws governing it).

    "the laws of physics are what prevent perpetual motion machines from functioning. That conclusion is already implicit in the working-out of those laws - it's not an additional, arbitrary principle that can be changed without changing the laws themselves."

    Sure, that's why you don't hear any philosophers arguing that there could be a physical duplicate of our world that allowed perpetual motion. (P & perpetual motion) is straightforwardly inconsistent. The zombie case does not appear to be analogous, however.

    "A world which contained the same objects and the same laws of physics as our world would be our world."

    That is the physicalist thesis. It is not an argument for it. I've offered an argument. Each premise is independently plausible, and indeed accepted by many physicalists. But if you accept all the premises, you won't be a physicalist for much longer. (It sounds like you want to reject premise 1.)

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  24. Adam,
    but if you consider a world with "psycho-physical bridging laws" to be "our world" why can't you also consider a world with a simple "perpetual motion machines can exist law" also as our world?

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  25. oh I suppose you are making the simple assumption that its necessarily impossible - in which case your directly in the headlights of Richards argument where he says somthing like "so why is it impossible? prove it.

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  26. Hi Richard -

    so from the posts and replies you've made your only argument that qualia aren't physical is (incredibly contraversial) Zombie intuition?

    Right?

    One of the normal replies is that the medieval philosopher could use exactly the same argument to argue that life itself must be more than just a physical phenomenon - we can conceive I suppose of a world with all the same physical laws, but with nothing alive. Or we could at any rate till we learned about evolution.

    What's your reply to that?

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  27. I discuss the vitalism analogy here.

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  28. Okay, thanks for the link. Reading it, it seems to your argument is that vitalism is different because it can't be reduced to functional terms. I'm not absolutely convinced that a vitalist needs to argue that, but I'll let it be for now.

    I must admit I found the following quote from you highly amusing:

    "You couldn't have a world physically identical to our own in all respects, but somehow biologically different."

    Exactly right :)

    Anyhow, more seriously you obviously think qualia aren't biological.

    So I return to the same question again - would be grateful if you could just provide a yes or no : is your sole argument or reason for thinking qualia are non physical the Zombie intuition?

    (If you could link to me to a reply about my second long standing question about the chain of causation of qualia in the object to our sensation, souls and the like, that'd be great too, but one point at a time I guess.)

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  29. I'm not sure what you're asking. My reason for thinking that qualia must be included in the base facts (i.e. they are not reducible to anything else -- physical or otherwise) is the argument given in the main post. If you grant that qualia are irreducible, but insist nonetheless that they are properly classified as 'physical', I say this is a mere terminological dispute. (See my responses upthread, e.g. to Clark.)

    Your second "long-standing question" looks to me like a meaningless jumble of words. I don't see any coherent question there.

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  30. On the first point, I agree that qualia exist as a distinct phenomenon (the sensation of blue is more than just the current physical description we currently have the frequency of blue light etc.) and that currently we have no idea how waveforms, particles and so on turn into our sensations. I do not agree that we have any reason to think that there is not a biological explanation for this.

    I think we can close off this area of discussion at any rate - I'm happy now that I understand where you're coming from, even if I reject it. (Which is ironic actually, as I started up this discussion rather fond of the Zombie argument. Oh well.)

    My second point is the same as I asked up thread - please reference my own post up thread ! :) :

    "b) The second point is what I was trying to get into in our last conversation on the topic : what is the epiphenomalist picture of how all this works? Qualia exist as non physical properties of our objects - but through what method or chain of causation do they cause our first person experience of them? Is that first person experience itself in my physical mind, or in a non physical soul?"

    In other words, if that's not clear, give me the physical (or non physical / spiritual) picture of how this all works. Or at least a hypothesis of how it might work.

    For example, I can see a table due to : light given off by the sun bounces off said table into my eye - which is converted into the visual information of a table by my brain.

    How does that work for qualia? How does the sensation get to me? What is the 'me' - physical brain, soul, non physical brain etc. ?

    Descartes had a picture of a soul, pineal gland, and brain - you seem to be rejecting that - but what do you put in its place?

    That's at the heart at what I've been asking for in all these discussions of souls and so on - the term 'property dualism' in response doesn't really tell me anything.

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  31. I do not agree that we have any reason to think that there is not a biological explanation for this.

    That's too strong. There are certainly reasons for doubting a forthcoming biological explanation. For instance, we've never called upon biology to explain subjectivity before. Certainly we can ask how a cell produces proteins and the like, or how organs work, etc. And asking such questions, we've gotten great biological answers. But we've never had an answer to a question for the why of a subjective experience. So skepticism is warranted here. Now these reasons may not control, but they are certainly there, and not insignificant.

    That being said, while there are reasons to doubt a forthcoming biological explanation, it may be that the parsimony of materialism is reason enough to bet on it.

    b) The second point is what I was trying to get into in our last conversation on the topic : what is the epiphenomalist picture of how all this works? Qualia exist as non physical properties of our objects - but through what method or chain of causation do they cause our first person experience of them? Is that first person experience itself in my physical mind, or in a non physical soul?

    I find this question odd. "How do qualia cause first-person experiences of them?" Aren't qualia defined as first-person experiences?

    But I believe I know what you're asking. Chalmers advances what he admits are tentative theories--briding laws--such that certain organizations in nature will produce certain qualia, as a fundamental rule.

    As to epiphenomenalism's response, Chalmers gives two basic responses that I recall:

    1. Qualia simply don't cause things--they are inert. Or perhaps qualia are redundant as causal agents--they cause something that is also caused by physical causes. Neither view seems fatal.

    2. We don't understand causation anyway, so it may well be that qualia are causal--we just need a fuller understanding of causation to see how.

    Richard's defended the first view on the blog before--the post being something like "Why do you think you're conscious?"

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  32. I don't like the jump from ideally conceivable to possible. Anytime you don't fully understand something you can imagine plenty of impossible scearios. How can we tell that that's not the case here? It's certainly fair to say that we don't know whether or not it's possible but that's not enough. What am I missing?

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  33. Ben,

    The argument is that the burden is on the other side to show why the scenario is impossible. Perhaps that's not where you think the burden should be, but it strikes me as the reasonable spot.

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  34. Genius:

    oh I suppose you are making the simple assumption that its necessarily impossible...

    I'm not making the assumption that it's necessarily impossible. I'm pointing out that there's no good reason to believe that it's possible (or at least, I haven't yet seen one).

    As I said in my previous comment, you can't just assert that it's possible to hold everything else about the world constant, but subtract consciousness. If you do that, you're not arguing for dualism, you're assuming dualism! Obfuscating this circular argument with terms like "psycho-physical bridging laws" doesn't make it any less circular.

    I'm not saying that this thought experiment is either necessarily possible or necessarily impossible. I'm saying that we just don't know the answer; and assuming what the answer must be, based on nothing more than our intuitions of what's conceivable, is a foolhardy endeavor. Sure, we can imagine a world that was exactly like our own in all physical respects but lacking qualia, just as we can imagine a perpetual motion machine that you can build out of stuff in your garage. But in both cases, just because we can imagine it doesn't mean that it's actually possible under the physical laws that pertain in our world.

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  35. Scott,

    > And asking such questions, we've gotten great biological answers.... For instance, we've never called upon biology to explain subjectivity before.

    You seem to be asking for a certain type of explanation obviously not the sort that traditional psychology, evolutionary psychology and neuro-psychology, and quantum physics provide.*

    So what sort of explanation is it?
    What form of answer would a physical explanation that satisfied you take? For that matter - what form of non physical explination would satisfy you?

    Do we have that sort of explination of an organ? I think probably not, and to add the other perspective - a physicalist would probably argue its a nonsense question.

    > Aren't qualia defined as first-person experiences?

    the issue this creates for me is 'do qualia communicate with each other?' if so I have a larger argument for you - if not, you are just tiny splinters of a person. do you really want to be a million individual things each with one sense for one instant (and thats it, no ability to self reflect on that), or to be the sort of meaningful thing that a physical human is?

    Adam,
    OK i guess we can term that the 'it's a draw, lets move on' argument? Sounds like what most of philosophy seems to have decided.

    ------
    *for example that we could make a human and control their behavior/subjectivity and know what we are doing we know why it isn't meaningful to talk about a rock having a useful perspective.

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  36. Hi Scott -

    1) I agree with you that qualia seem a different sort of problem than we've had to solve before. But that goes without saying to some extent - if it was the same sort of problem as we'd had before, we'd have solved it by now. Lots of ways of trying to classify it into its own special unsolvable category ("we need a more functional explanation", "science has never had to solve phenemology" etc) are basically just restating the question. Yes, we know the problem is subjectivity. No, we haven't solved anything like it yet, as we haven't solved subjectivity yet.


    But it doesn't seem at first glance (or even a priori) harder to me the problem of life does, or did. With science's track record in eventually coming up with solutions, I think it certainly deserves the benefit of the doubt - especially as we're nowhere near finishing exploring the physical structure of the brain or how it works.

    Evangelical Christians rightly get criticised for resorting to "god of the gaps" sort of arguments. I think its a sad day if philosophy has to resort to the same sort of thing.

    I sense you agree with me mostly in substance, but differently in emphasis. The incompatibility of relativity and QM is a problem for physics - it is not a reason by itself to deny physicalism. The burden of proof seems to me to hugely be on the side of Richard's team to show why this case is different to other unsolved problems.

    At the moment their argument seems to come down to some sort of gut instinct "it just is different" (or in longer form "I can imagine it not being a consequence of the laws of physic and biology, therefore it could not be, therefore it isn't" etc.) - and I'm very uncomfortable with philosophy proceeding on that basis, rather than argument, logic and empirical data.

    2) On the second point, I still don't see a complete picture of how this works.

    I think some confusion may be coming in my sloppy use of the term 'qualia'. I'm less concerned about what qualia go on to cause, than what is it that causes qualia/the experience in the first place? What is the medium that gets the sensation from the object to the qualia? And what / who is it that experiences the qualia?

    Chalmer's bridging laws seems a bit of an explanation for the medium answer of that at any rate - though rather ad hoc. It doesn't say who the who is.

    Basically if

    Object -> light -> eye-> brain

    What's the equivalent for qualia?

    Object -> 'bridging laws' -> ?

    Richard seems to have rejected

    Object -> 'bridging laws' -> non physical brain (/ soul)

    which would be the classic dualist explanation

    So I can think of 2 possible further explanations:

    Object -> 'bridging laws' -> physical brain

    which doesn't seem to be ephiphenomenalist


    Object -> 'bridging laws' -> qualia

    in which our soul is nothing more than our experience of qualia. They're floating separately and not cause of anything back in the physical world - they just 'experience' as it were, without making decisions, or having any personality or intelligence of their own, or cohesive unity (all that stuff exists back in the physical mind and brain).

    The last seems to best I can do to put together all the strands of Richard's position into some sort of coherent picture.

    Richard, is that what you're saying?

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  37. Here is a hypothetical model of qualia...

    1) qualia are not effected by entropy or any similar laws independent of the physical world (otherwise we might notice the effect). So you can have any number of qualia in any instant and it costs nothing to access them.
    2) qualia are highly atomic - i.e. red could be 10 or 1000 different unique qualia added together (the reason for this is
    A) that there is a theoretical experiment where I start a qualia in a person's brain that would have been red then stop it halfway and still have a result
    B) and the way we construct meaning from words is reducible.

    This implies it is reasonable to think there is no individual qualia that has any sensible meaning, but there may be multiple sets (collections of qualia triggered by a state of mind) with more or less the same meaning.

    3) the way the law picks what pattern to use is extremely complex, because it has to give some apparently different patterns. the same results and similar patterns different results.

    4) the presumably rich nature of human experience means that a yh'person' can experience qualia and yet not know it in the same way they can hear a sound and yet have no record of that even an instant afterwards. This is just a failure to connect the data to the main part of your brain - but the qualia have been created so it shows the qualia can be absorbed by you and yet not be 'felt' by 'you' in a certain sense (hence the quote marks).

    5) Memories of qualia refer to different qualia (the reason for this is that the pattern triggering them has different physical traits so should trigger a different qualia, although it is presumably a similar qualia for similar reasons to why a physicalist would say it seems similar)

    Maybe no qualia is ever reused.

    6) zombie contain no value no matter how organized they might be - so I'll say qualia carry value in and of themselves - so a blinding flash of qualia is a state of value. It is also of course a 'perspective' regardless of if it forms a structure with meaning (like a thought).

    I imagine you could take different position but that's a model.

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  38. Jonathan,

    But it doesn't seem at first glance (or even a priori) harder to me the problem of life does, or did.

    We have a different intuition then. I can imagine a functional analysis of many things--even things we don't yet have explanations for. I have no clue how subjectivity arises.

    At the moment their argument seems to come down to some sort of gut instinct "it just is different"

    I agree that much of it comes down to this, but I don't see that cutting one way or another. Dennett's got a gut instinct for materialism. Many a dualist has a different one. Okey doke. Now what?

    Your description of Richard's position on the causal chain of qualia seems apt.

    Genius,

    So what sort of explanation is it? What form of answer would a physical explanation that satisfied you take?

    If I could tell you the form of the explanation, we wouldn't have a problem. But I can't imagine the form such an explanation could take. Hence, I'm skeptical of a forthcoming physical explanation. If your point is I'm asking for a different explanation than is typical, I readily agree, and the reason is because we're dealing with a different phenomenon than is usually dealt with, which was of course my original point: that consciousness is different.

    For that matter - what form of non physical explination would satisfy you?

    Several dualist theories strike me as promising. Chalmers's dualism, quantum mind hypotheses, et al, all usually involving the postulation of some new fundamental in nature. And I'm not opposed to McGinn's mysterianism.

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  39. Scott :

    Well, first off, if we're just trading gut instincts, then we can stop calling it philosophy I'd have thought :)

    I might add Dennett goes far further than me - he denies qualia altogether, which I agree is a similarly unreasonable position, drawing huge and paradigm changing conclusions from flimsy evidence, rather than just accepting "we don't know yet" (more in common with Chalmers than perhaps he'd like to admit).

    I'm surprised that you so easily seem to have been able to imagine a physical solution to life - it was after all a problem that has (and still does) lead many to feel materialism is inadequate and that a God or some spiritual realm is needed.

    Neither do I see a ready answer in today's science to Why does anything exist rather than nothing? How does causation work? etc and other similar points about fundamental physics, which I have no idea how a 'functional' theory could explain. I guess that's why philosophers love talking about them too...

    Richard seems to think that this weird picture of qualia floating on top of the normal physical universe is more reasonable than saying science just hasn't got there yet. You can disagree on that point, but I don't think you can say each side is equally valid - to be rough the best type of theory should be say simple, elegant, fit the results so far, and make predictions that we can test. A theory that wants to completely redefine our metaphysics should be especially so!

    If the idea of a non physical qualia solved more than one metaphysical problem (and the idea of soul, for all you might say against it, at least did that), then it might be an intriguing idea.

    At the moments its no more than an ad hoc add onto our normal picture of the world hurriedly crafted onto to solve one mystery, and that's why I think the burden of proof is massively with Richard.

    Good to know that I think I've finally got a word description of the epiphenomalist picture of qualia. Been dwelling on it all day, and the more I think of it, the less sense this idea of disembodied qualia, experience without an experiencer makes to me, but there you go.

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  40. Jonathan,

    If we were just trading gut instincts, then yes, that's not really philosophy. Thankfully, I never asserted that's all it comes to.

    I might add Dennett goes far further than me - he denies qualia altogether, which I agree is a similarly unreasonable position, drawing huge and paradigm changing conclusions from flimsy evidence, rather than just accepting "we don't know yet" (more in common with Chalmers than perhaps he'd like to admit).

    Chalmers proceeds from the idea that there is something to be explained, whereas Dennett denies the very thing under question (and admits the counterintuitiveness of his conclusions). To me, Chalmers is the more modest of the two.

    I readily accept "we don't know yet" (a principle, by the way, that Chalmers and Dennett both embrace). But the debate here is between you, who seem to believe the answer is "we don't know yet, but the answer will be a materialist one" and me, whose answer is "we don't know yet, and we won't know if the answer will be a materialist one."

    As to which view is weirder, every view is weird, and you seem to agree, as you part ways with Dennett. If that leaves us in the middle, with a wait and see attitude, then I can live with it, but there's no reason to presume materialism while waiting. E.g, Dennett has taken the challenge seriously, and pushed materialism to its limit--the result is an absurdity, as you admit. All the more reason to be skeptical of any who assert that materialism is of course true.

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  41. Scott :

    Again, Dennett is implying more than a materialist viewpoint - he's implying qualia don't exist full stop.

    What does it come down to if not gut instinct then?

    Fine, we don't absolutely know that the answer will be materialist in that it can't be proved a priori.

    But I just made a whole post about why materialism is by far the best bet, which I'm not sure you've replied to any of - except to suggest that "every view is weird".

    That's simply not true.

    Here is my position :

    a) qualia exist
    b) like everything else in our mind, they eminate from our brain
    c) like everything else in the mind, we don't understand how yet

    None of that is weird!

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  42. Cheers Scott,

    It seems to me that the position of not knowing whether it is possible should be the default and anyone claiming to know whether or not it is possible should provide a strong argument. To me a physicalist description would be anything that can be expressed mathematically, so the dualist would be correct if the universe could never be fully described in this way. I find physicalism more convincing because I don't see any strong evidence against it and it has less ingredients than competing theories.

    Although I think we'll probably never really understand how our consciousness arise out of maths, in the same way we will never understand why anything exists, I do think that as we better understand how the brain works we will start to associate the concept of a qualia with a physical property of the brain, because that will be a useful way of talking about it. If we find that certain of our own physical patterns are always associated with certain mental states, and we start to be able to physically measure the connections between sensations, our thoughts, feelings, actions and memories we won't think that some non-physical ingredient is necessary to explain the correspondence. We will simply default to the simplest satisfactory explanation as we typically do and should.

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  43. Jonathan,

    Dennett is working out the implications of the materialist viewpoint. That leads him to the denial of qualia. The denial of qualia is not an independent step--it's an outcome of the materialist view. At least, that's how I understand his argument.

    Perhaps you're one of Chalmers's type-B reductionists instead, a la Searle. But that view doesn't strike me as particularly robust either, so I don't think it much affects what I've said. To wit, I think you'll hit an absurdity either way.

    As to what beyond gut instinct it comes down to, we have reams of literature on philosophy of the mind, we have Kripkean analyses and thought experiments, we have proofs and premises, we have empirical implications and talk of supervenience, modal claims and more. Now, if you want to say that in the end that all comes down to gut instinct, well then, so does everything.

    But I just made a whole post about why materialism is by far the best bet, which I'm not sure you've replied to any of

    If you mean the penultimate comment of yours that I responded to, I'm afraid I don't see anything in it that suggests materialism is by far the best bet. There is the analogy with the elan vital, but that's not persuasive, and, at any rate, has been addressed.

    a) qualia exist
    b) like everything else in our mind, they eminate from our brain
    c) like everything else in the mind, we don't understand how yet

    None of that is weird!


    B is pretty weird, in my view. Subjective experience from objective matter is quite the stretch--and if I didn't have personal experience with the phenomenon, I'd probably say implausible.

    Now it may be that once we find out how it happens, once we crack your "c)", it won't seem so weird. But I could say the same thing about a dualist explanation.

    So this is a wash.


    Cheers Ben,

    Yes, there are some who simply assert an identity between qualia and neural states and leave it at that. I disagree that that will ever be satisfying, because of course it's logically possible that the identity not hold, so there's something that needs to be explained. This differs from other ideas: we can't conceivably vary biological facts, for example, without varying the physical facts upon which they supervene. But we can easily do so with phenomenal facts.

    But this is of course only Chalmers's argument, and there's not much point to me restating it.

    As to the burden of possibility, I'm afraid we just disagree. If one can describe a scenario with no apparent contradictions, then that's enough prima facie evidence--for me--that the scenario is logically possible. YMMV.

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  44. Scott,
    Thanks for fleshing out your position a little.

    I was just about to suggest you might be heading towards McGinn's mysterianism.
    Maybe we could propose "the solution is necessarily unknowable"? I am inclined towards that for this sort of qualia if qualia exist.

    It seems to me that the problem remains where Chalmers's dualism, quantum mind hypotheses, et al add another level but don't 'explain' in the sense we want. I.e. we can still ask similar questions even after any of these solutions are proposed. this reminds me of the 'god did it' explanation which is followed by 'why?'. (That, in itself, doesn't mean that they aren't true of course.)

    it seems a little like the old story of the earth resting on a tortoise

    > Subjective experience from objective matter

    I wonder if this comes down to the 'why am I not you' question.

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  45. Hey Richard,

    I'm still not sure what your response was to my response on behalf of the physicalist from before. If you get the chance, I'd like to know. I think this issue is interesting, but I'm just not yet convinced by these sorts of zombie arguments.

    You asked what the physicalist can say to explain something like the unreliability of the relevant intuition. It went something like this:

    If what we need to know to grasp concepts of phenomenal properties is in part indexical or demonstrative knowledge and there is no apriori connection between descriptive (non-indexical and non-demonstrative) knowledge and indexical/demonstrative knowledge, the inability to deduce, infer, or whatever the phenomenal from the rest is just no more reason to assert that the phenomenal properties can possibly come apart from the physical. I can't tell if you disagree about the relationship between descriptive knowledge and indexical/demonstrative knowledge or if you think we can have knowledge of the phenomenal and grasp of the relevant concepts without needing such indexical/demonstrative knowledge. So far as I can tell, this _is_ the story the physicalist will tell about the reliability of these modal intuitions. Non-indexical descriptive knowledge does not give us a reliable guide to determining what indexical or demonstrative knowledge there is or could be. The inability to describe the world's phenomenal profile given a complete description of the physical profile is no more surprising than, say, the inability to connect the 'here' and 'now' facts with facts stated in non-indexical terms.

    A friend of mine is working out a view along these lines. It goes something like this. The base facts from which the further facts are supposed to be derived from knowledge by description, so to speak. The physicalist will say that the high level facts are known to us by acquaintance, things we know de re, what have you. There's no real way to draw rational connections that allow us to move from descriptive knowledge to knowledge of Russellian propositions (the objects of knowledge by acquaintance). That's why it's not surprising that we cannot read the qualia facts off of the physical facts. We cannot read any of the 'facts' known to us through acquaintance in this way. But, that does nothing to show that these facts are not necessitated by the lower level physical facts.

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  46. Scott:

    all of these "reams of literature" seem to come down to this single instinct that "subjective experience from objective matter" is weird. I have yet to see any argument which doesn't fundamentally rely on that point, which in itself is always unargued for.

    The point I don't think you responded to was

    "the best type of theory should be say simple, elegant, fit the results so far, and make predictions that we can test. A theory that wants to completely redefine our metaphysics should be especially so!

    If the idea of a non physical qualia solved more than one metaphysical problem (and the idea of soul, for all you might say against it, at least did that), then it might be an intriguing idea.

    At the moments its no more than an ad hoc add onto our normal picture of the world hurriedly crafted onto to solve one mystery, and that's why I think the burden of proof is massively with Richard."

    If I don't understand lighting, sure I can just say Thor did it. Lighting looks like nothing else in the natural world. But I'd do a lot of a better to wait a thousand years for someone to describe electricity, a universal phenomenon which describes many, many other problems and has testable predictions.

    As I've said previously, most arguments come down to "subjectivity is weird, because its subjectivity", or "we've never solved anything like subjectivity before" to which I say duh.

    Life was like nothing we'd never seen before. So was lighting. So is fire for that matter to go a long way back.

    If you want to say that subjectivity is weirder than the above examples, then give me a reason why it is so, don't just state "because it's subjective."

    If you can't, then sure you can hold onto your gut instinct that this time just is different - but I repeat you're not doing philosophy, you're making a statement of faith, and so I suppose there's no real point in us debating any further.

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  47. Clayton - maybe something like that could help the physicalist, though I'm not entirely sure I understand the proposal. I certainly don't think it's generally true that "the high level facts are known to us by acquaintance" only. I think the facts about tables, etc., are a priori entailed by microphysics. And it's not entirely clear to me why qualia should be any different. Perhaps one needs to have experienced redness in order to have the phenomenal concept, but once you have the concept (and note that we assume the idealized agent is granted full grasp of all relevant concepts) you can reason about it in descriptive terms. For example, if we include in the base facts the psycho-physical bridging laws that such-and-such physical arrangement gives rise to such-and-such qualia [insert image of phenomenal redness], then the ideal agent can infer from this base (and the physical facts) what qualia there are in the world. I'm not sure what reason we have to think that the bridging laws are unnecessary here. But maybe I'm just misunderstanding the proposal.

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  48. Richard,

    You wrote:
    I certainly don't think it's generally true that "the high level facts are known to us by acquaintance" only. I think the facts about tables, etc., are a priori entailed by microphysics. And it's not entirely clear to me why qualia should be any different.

    I think that what the materialist will say is that if we have no reason to think that high-level facts in general will be apriori entailed by low-level facts, there's no reason to place much trust in certain kinds of modal intuitions. The proposal is not that it is a general feature of high-level of facts that they are typically known to us by acquaintance. Presumably the only things we'll know by acquaintance are things to which we have privileged access (e.g., beliefs, sensations, etc...).

    I'm not sure what to make of your proposal about how we might still have to run the thought experiment once this wrinkle is introduced. I'll have to think it over.

    There are other cases that I think pose a challenge to the project of cosmic hermeneutics that suggests that apriori connection is no test for necessity. Think about Chisholm's paradox. Don't facts about which persons exist in which worlds count as high-level facts that we cannot recover from descriptions of the low-level facts? It seems we might have two worlds indiscernible with respect to the basic physical facts but discernible with respect to the identity of the objects in that world. (Someone might take this to show that persons are ontologically special, but we can run the relevant thought experiments with ships, sticks of butter, pencils, etc...).

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  49. Right, I'm a reductionist about identity for that reason, i.e. I don't think that duplicate worlds (differing only in their identity facts) are really conceivable. See my posts under the sidebar category 'metaphysics - identity'.

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  50. But if _that_ were the reason for going reductivist, it seems you're essentially moving the goalposts.

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