Wednesday, February 08, 2017

Our Zombie Bodies, and Physicalist Epiphenomenalism

Eric Olson has a fascinating paper, 'The Zombies Among Us' (forthcoming in Nous), where he points out that standard constitutional theories of persons imply that our bodies are phenomenal zombies -- physically identical to us but lacking conscious experiences (or indeed any mental properties).

Constitutionalists hold that we are constituted by (but not identical to) the physical matter that makes up our bodies.  If we imagine a brain-transplant case, for example, it seems that we go where our brains go, and so we can come apart from our bodies (and likewise from the biological organism that our bodies also constitute).  But then we must deny that our materially coincident bodies have mental properties (such as the belief that we go with our brains and not with our bodies), on pain of a fairly radical skepticism (if bodies have all the same beliefs and thoughts as us, what confidence could we have that we are not ourselves such thinking bodies, falsely believing that we go with our brains?).

So, in the ordinary run of things, our bodies are physically identical to us but lack mental properties: they are philosophical zombies.

Not in any sense that refutes physicalism, of course; our brains may still metaphysically suffice for (giving rise to) consciousness, even if we do not then attribute the consciousness to every object that has our brains as parts. (Which makes independent sense, after all: we can speak of a gerrymandered object consisting of my brain + the Eiffel Tower, but we should not hold that this object is itself a thinking thing.)

An interesting consequence of this, which Olson flags, is that physicalists should not identify mental states (or properties) with physical states (or properties).  Any token physical state that I am in is shared by my body, after all.  So if mental states were identical to token physical states, we would be committed to holding that my body shares my mental states, contra the view expressed above.

Instead, I think, physicalists should agree with dualists that the brain gives rise to (rather than just is) the mind.  Their view can remain distinctively physicalistic insofar as they insist that there is nothing metaphysically heavyweight about this "generation" -- the mind comes along "for free", in something like the way that computer hardware gives rise to a running software programme.  Your web browser is not identical to any of the circuitry upon which it runs, but nor does it create any deep metaphysical mysteries. (Of course, I think consciousness is different, but I'm playing Devil's advocate for the physicalist here.)

An interesting upshot of this (it seems to me) is that physicalists should be epiphenomenalists too.  These "virtual" or abstractly generated mental properties do not push atoms around, and so lack fundamental causal powers (though we can always invoke them when speaking loosely, as in correlative explanations).  This isn't a problem, since there's nothing wrong with epiphenomenalism, but insofar as many physicalists believe otherwise, it does put them in a funny position.

[See also: the 'Virtual Mind' diagnosis of why Searle's Chinese Room argument is misleading, for related discussion of how mental properties should be attributed to a different 'level' of entity from that which does the underlying information processing.]


  1. "So, in the ordinary run of things, our bodies are physically identical to us but lack mental properties: they are philosophical zombies."

    I thought a philosophical zombie was a creature that wasn't conscious, but acted the same as a physically identical conscious creature? A body with the brain removed would not act the same as an otherwise identical body with the brain still attached. The former would drop dead, the latter would keep on moving.

    Our bodies aren't physically identical to us, but lacking in mental properties. We are the mental properties, a body is just a fleshy robot the mental properties pilot around. A body with the brain removed isn't "you" anymore. It's a hunk of dead meat. That's why it's legal to cremate a corpse, but not to cremate a living person.

    It isn't accurate to say that all bodies have the "same beliefs" unless you count having zero beliefs as having the same beliefs. If that is the case then not only do two people's bodies have the same beliefs as each other, they also have the same beliefs as rocks, trees, and lakes.

    1. Certainly if its brain was removed, a body would cease functioning. But in the ordinary run of things, our bodies have our brains as a part. So the question is whether that whole physical entity (brain actually included, but not essentially so) has beliefs and other mental states.

      I take it your suggestion is that physicalists should not hold a view on which we, as persons, are constituted by our entire bodies, but only by our brains? There are some costs to such a view, in that it seems a bit awkward to say that we do not literally have hands, etc., as parts of us, but only as part of a "fleshy robot" (as you put it) that we control. An advantage of constitutional views is that we get to fully claim our bodies without being counterfactually wedded to them (we could have been differently constituted).

      In any case, the same puzzle may re-emerge with the brain case if you accept a purely psychological ("software, not hardware") criterion of personal identity according to which you are merely constituted by (not identical to) your brain, since you could survive being "uploaded" into a different cognitive vessel. If you believe that you could be transferred to a different brain, does your brain also believe this? It'd better not. So we had better deny that brains have beliefs or mental properties.

    2. "If you believe that you could be transferred to a different brain, does your brain also believe this? It'd better not."

      I am not sure what this means. I don't see anything contradictory about my brain believing I could survive being transferred to another brain.

      Do you mean that if I believe I can survive being uploaded to another brain, that implies that my brain believes it could survive too, and that doesn't make sense since my brain is a physical object that can't be uploaded? In that case I think the problem is that you are treating the referrant of the term "you" as changing from my psychological identity to my brain's physical structure. Sort of like if someone read a diary written in the first person and concluded its contents must be false because books are inanimate objects and cannot do all of the things that the "I" writing the diary describes doing.

    3. Yeah, sorry for the ambiguity, I meant the latter. Given the indexical nature of "I", any entity with a belief of the form "I could survive being uploaded" is attributing the property of uploadability to itself.

      Now, it would indeed be a mistake to attribute beliefs to a diary. Should I take it from your invocation of this analogy that you agree it would be a mistake to attribute beliefs to our brains?

  2. "These 'virtual' or abstractly generated mental properties do not push atoms around, and so lack fundamental causal powers..."

    This is an interesting thing to say when using the computer analogy. It seems to me that the virtual components of a computer can AND DO have some impact on the physical composition of the computer. Perhaps not the way it's structured (in terms of circuitry) but certainly in terms of how information is read from the hard drive (the way electricity runs through the device). That's basically what reformatting a hard drive is all about: you don't change the actual physical object but the way it works is radically altered. There is a physical change, regardless.

    In that sense, why can't we say that the mental properties we have are inputs that can be fed into programs that alter the format of our hard drives (the general electrical patterns of the brain)? Then it's not so much about the way the atoms are placed in the brain but rather the way electricity flows is the key to understanding ourselves on the physicalist's account. That would still impact the atoms, but it's not the atoms that are the real point of interest here.

    This conception is also consistent with the constitutionalist's account. As long as the pattern of electrical flow is the same then you'd still be yourself even if you transferred bodies with your brain: your brain has an electrical flow unique only to you and so in putting it in another body you preserve yourself in that sense. So perhaps the physicalists are barking up the wrong tree by conceiving us as atoms and not as electrical flows? Some food for thought.

    - The School of Stupidology (a new philosophical blogger on the block)


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