Zombies

Having read through the first third of the paper or so, here's some thoughts.<p>I'm not convinced by the fact that showing 'possibility' of zombies is enough to eliminate physicalism. The argument they use is too slippery for me to grasp, but it basically sounds to me something like this:<p>Skeptics think that the laws of physics are sufficient to describe the universe. It suffices to show that magic is possible, and then skepticism is false. This is why opponents of skepticism do not have to point to actual cases of magic being performed; it is enough if such things are possible.<p>Second, along the lines of conceivable -&#62; possible, here's an interesting thought experiment.<p>I can conceive of an immovable object. An object such that when it is inserted into our universe, it can never be moved with respect to some frame of reference. Such an object is much easier to conceive of than a zombie.<p>I can conceive of an irresistable object. This object is such that it moves with constant velocity relative to some frame of reference, and its velocity can never be changed.<p>I find it hard to accept that the possibility of such concepts can be used to show anything useful about the universe.<p>Further on, I found that the best counterexample included was that of Daniel Dennett, who compares the idea of consciousness against the idea of health - to quote the quotation:<p>Supposing that by an act of stipulative imagination you can remove consciousness while leaving all cognitive systems intact — a quite standard but entirely bogus feat of imagination — is like supposing that by an act of stipulative imagination, you can remove health while leaving all bodily functions and powers intact. … Health isn’t that sort of thing, and neither is consciousness (1995, 325). &#60;end quotation&#62;<p>Finally, it's nice that they went out and mentioned all the issues with semantics around the concepts of 'conceivable' and 'possible', because that was the part that feels like it wants to give me a migraine.<p>Last thought: One of the ideas was that whatever it is that distinguishes us from zombies does not exist in a physical sense. But we have devices that can read our thoughts - or at least show that our physical state is changing while we think.<p>My MRI shows brain activity, therefore I am.

Eliezer Yudkowsky lays out the Bayesian reductionist argument in his Zombies sequence: <a href="http://wiki.lesswrong.com/wiki/Zombies_(sequence)" rel="nofollow">http://wiki.lesswrong.com/wiki/Zombies_(sequence)</a><p>It's a good accessible read, mentions a few of the interesting questions zombies can shed light on, and has a fair number of reader comments and responses.

The problem with philosophical zombies ("p-zombies") is that, since they're indistinguishable from normal humans, some of them must go around talking about qualia and consciousness and so on; it's mysterious what's causing them to do this, since they don't actually have any qualia or consciousness.<p>This is the strongest argument that mind is matter: mental things like qualia clearly do cause physical events (e.g. discussions about qualia), which seems to suggest that qualia etc are themselves physical, since we expect physical events to have physical causes.<p>(And yet I can't stop wondering how being a collection of atoms feels like anything.)

I've lost count of the number of times Zombies came up in our Philosophy of Mind classes. The classic question was always "if consciousness can be entirely reduced to physical phenomena, then isn't the only difference between a zombie and a person that they have different brain states (or a lack of certain ones)?"<p>That made people very uncomfortable about a lot of things, and really demonstrated the group feeling that consciousness has to be some other substance. A lot of great conversations about verifiability, positivism, philosophy of mind, and naturalism/materialism were started with Zombies.

For some reason these arguments all seem to start with the assumption that <i>we</i> are not all zombies. I have yet to see any good evidence that we aren't and it seems like the simplest explanation.