Holding to non-Reductive physicalism has some benefits….
First, it takes seriously the dualist’s intuition—and the biblical data—that we cannot be reduced to the material; that is, we are more than merely matter. Second, it might avoid the reductionist pitfall of eliminating moral responsibility. Some people, like Nancey Murphy, have argued that can provide an account of moral responsibility by appealing to evaluative action loops. Maybe she’s right, maybe she’s wrong. Third, the nonreductive physicalist takes very seriously the deliverances of contemporary neuroscience. Whereas some versions of dualism can be accused of failing to account for why our conscious and mental life is so intimately tied to our brain and neural states, the non-reductive physicalist does not face this accusation. Finally, because the nonreductive physicalist takes a physicalist position, she is in a better position to dialogue with scientists and philosophers. This is because the majority of scientists and philosophers hold to some kind of physicalism and reject dualism. Despite the benefits of this view, however, the nonreductive physicalist position faces some challenges.
One challenge that nonreductive physicalism faces has been articulated by Jaegwon Kim. According to Kim, nonreductive physicalism leads to an incoherence. Kim’s argument goes as follows:
- According to nonreductive physicalists, a mental event M leads to some physical action P*.
- M under traditional accounts of causation is the cause of P*.
- M supervenes on some material base, P.
- P under traditional accounts of causation is the cause of P*.
- Therefore, M is the cause of P* and P is the cause of P*.
- Overdetermination of causes is incoherent.
- Given 5 and 6, the nonreductive physicalist view is incoherent.
A nonreductive physicalist might respond to Kim’s argument in several ways. She might deny the traditional account of causation. This seems like a steep price to pay. She might deny that overdetermination of causes is incoherent. Yet this is precisely what physicalists say is the problem of dualism. (E.g. My body and my mind cause my left arm to raise. This is incoherent because it is an overdetermination of causes.) Finally, she might say that neither M nor P is the cause of P* but that the entire system which is constituted by M and P is actually the cause of P*. Such a response would need to be further fleshed out to be convincing. In light of these possible responses, Kim’s point still stands, the nonreductive physicalist will need to develop their account of causation to make nonreductive physicalism plausible.
There are a few more problems that I see with the non-reductive physicalist view. I’ll point them out in another post.