At some point, every man has been told to think with his head rather than, well, his dick. Watching a long and not always funny bit by Margaret Cho about her own genitals made me think about this. As she went on and on about parts I neither possess nor have much experience with, I was thinking both how strange it would be for me suddenly to find myself in possession of a vulva and how that would affect at least some of my thoughts. (At this point, I was also thinking about Thomas Nagel and Madonna.)
That is not, of course, to say that it is strange to be a woman, but to say—what is probably obvious—that I have always experienced the world as a male. And, this doesn't mean just being treated as a boy and now a man by others, it also means having a certain sort of body, a body with which I am constantly in contact and in which and through which I experience the world, through which and in which I think. It would be strange for me to have a woman's body.
I'm not going to argue that this means that there is something essentially different in the thoughts of men and women; that gets the scope of my concern wrong. I began thinking about this in terms of sex, but the issue is more fine-grained. It's not that my thinking has always occurred in a particular kind of body; it has always occurred in this body. (Obviously, it has also always occurred in a body.)
For the good old substance dualists, the body had very little to do with thought, at best serving as an ancillary for gathering materials. But, almost no one (at least among philosophers) still holds on to substance dualism. We are all, or mostly, some sort of physicalist now.
But, at least some physicalists seem implicitly to accept something like the old dualism. Consider the way that futurists and transhumanists argue that we will be able to live forever as computer programs or cyborgs or something else yet to be envisioned. Or, even the way in which both Daniel Dennett and Derek Parfit—intending ultimately to undercut our notions of personal identity—among others, place the kernel of our existence in a psychological continuity that is located wholly within the brain.
They ask: Where would I be if my brain were transplanted into the body of my partner and his were transplanted into my body? The assumption is that it is obvious that I would be wherever my brain is, because that is what would have psychological continuity with me. But this assumes that my psyche is divorced from the rest of my body and resides fully within my brain, that the composition of my body matters not at all to my mind or my thought processes.
They ask: What should we say if there were an exact replica of our brains in a computer or if our brains were in a vat but our body was at a distance? Won't we be able to survive bodily death if we only upload before then?
The same assumptions underlie these sorts of question. And, they exhibit a dualism—a lazy brain/body dualism—that is perhaps more problematic than good old Descartes'. He may have thought that the mind was a non-material substance, but at least he thought that (somehow) that mind permeated the entire body. Now we have a view where the mind exists in a throne-room, connected to the body only contingently. This ignores, in a way that one who wants to be naturalistic, the way in which our cognition—not to say all cognition—is embodied.