Physicalism, Property Dualism, and Personal Identity (II)

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Brett has suggested that my critique of property dualism as adequately grounding personal identity fails. Here I will attempt to respond to his criticisms of my argument.

Brett wrote:

Michael introduces this as a critique of type-property dualism, but this seems to be another critique of token-property dualism taken from a different angle. Michael points out that the second tape is a “different tape” from the first one, which seems analogous to the difference between the first token-molecules of the mind being different in token to the second token-molecules of the mind, even though they are the same type throughout. But as Michael himself points out the same image will pop up on the screen, and so he agrees that it is the same “type” and that nothing has changed as far as “type” even though, with the switching of tapes, things have changed with “token.” And since the “type” does show continuity between the exchanging of tapes, this hypothetical situation does correlate to what we experience phenomenological. So, in the instance of property dualism, where aspects of consciousness are the emergent property of brain chemicals, it seems that the changing of brain chemicals will not interfere with the belief, feeling, or image that it emergently creates.

Brett says that I am giving a critique here of token-property dualism. But what I am really arguing is that type-property dualism is counterintuitive. Its correct that I am pointing out that the second tape of the same type is a different token from the first one, analogous to the difference between physical state X token A and token B. And yes, the same type of image will appear on screen. So there is continuity of the type of image even though there’s two different tokens.

But that’s the whole problem. Personal identity, whatever it is, has to involve total continuity and sameness across time. Now think of how property dualism articulates personal identity. If a ship lost its mast and got a new mast, we wouldn’t say that it was exactly the same ship. Whatever we believe about personal identity, we can’t believe that its grounded in switching the ship’s mast every time it falls off; that’s precisely *not* a continuity of identity, but two totally different things. Similarly, two different showings of the same film are *not* the same film. They are two very different things.

Now, the continuity of mental states Brett is imagining that gives us personal identity is like the continuity between two different showings of the same film on a tv screen. Its two very different things, not having any of the exact same parts or properties in common with previous states of the mind. Two different video tapes have successively gone into the VCR, and now the image being projected on the screen is a different one from before. This is not a continuity but precisely a discontinuity of identity between this showing of the film and the previous one. It may be displaying the same image, but we would not say its the *exact same film*.

Its like the replacement mast on the ship: sure, its a mast–but its not the same one as before. And similarly this is not a continuity but precisely a discontinuity of identity between this mental state and the previous one. Thus the continuity that is suggested by this theory of personal identity is like the replacement of one mast on a boat with another mast–hardly adequate for claiming numerical sameness throughout time in the sense necessary for *identity*. At most, this theory of personal identity seems like it can be dubbed a theory of *personal similarity*.

In Brett’s next section he talks about how substance dualism is unparsimonious. This may be true if we have no arguments for it. But of course an argument for dualism from the inadequacy of non-dualist theories of personal identity would qualify to override this appeal to parsimony. For if materialists can’t explain personal identity, and property dualists can’t explain personal identity, then parsimony should be set aside for the explanatory power of substance dualism.

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