Nonreductive realization physicalism

A view that has been gaining popularity is that we can appeal to the idea of realization to explain how mental events (exemplifications of mental properties) can be causes without being physical events (exemplifications of physical properties). The idea that mental properties are realized by physical properties is not new. ° But Kim s work on the problem of mental causation seems to have played a major role in inspiring the recent spate of attempts to appeal to physical realization to explain how mental causation is possible. Kim (1998b) labels this viewpoint realization physicalism, but it is also sometimes called nonreductive physicalism. For reasons that should be clear in due course, I will call it nonreductive realization physicalism. The core of the view is this ... 

Nonreductive realization physicalism (NRP) No mental event is a physical event, but every mental event is realized by some physical event or other. 

After the initial hype about supervenience being the answer to a form of nonreductive physicalism, it was realized that it delivered no goods, and in the past few years inter-... 

This principle could be taken to mean that every good causal story we can tell has to be couched in physical terms or that all causation is always in virtue of physically definable or reducible properties. Taken this way, however, this principle would just beg the question against nonreductive materialism. Under physical causal closure, it is not that we can never invoke physically irreducible higher-level properties as causes for a physical event. We may very well cite some irreducible mental property as the cause of some physical event. The point is that this mental property, if it is to be causal, must somehow be anchored in the physical world. It must be tied to the physical by some sort of supervenience or realization relation. This close tie to the physical will always make it possible, in principle, for us to tell a causal story in terms of physical properties, even though the best causal story might not always refer only to physical properties. Thus, we will never be forced to go outside the physical domain and refer to physically irreducible properties in order to find a sufficient cause for a physical event. So the principle of physical causal closure requires that if we pick any physical event, it will always be possible, in principle, for us to find a purely physical causal chain for that event. So if we take any physical event P, we should be able to find some property or group of properties P, such that P is physical and P is a sufficient cause for P. ... 

Now how does all of this pose a problem for nonreductive materialism Nonreductive materialism holds that although every mental property supervenes on some physical property (and is possibly also realized by tiiat physical property and token identical with it as event), mental properties are neither type identical with nor reducible to physicjd properties. Now in order to give an adequate account of mental causation, the nonreductive materialist will need to be able to say how it is that mental events can be causally potent - i.e., how can a mental event M cause another mental event M to occur, and how can a mental event M cause a physical event P to occur Now if we are working with a Davidsonian model and we have token identity, where every mental event is token identical with its physical instantiation base, then there is no problem with event causation. Mental events are causal because theyjust are physical events. But the... 

Aecepting nonreductive materialism gets us what we want and need out of a theory of mental causation. We can have sufficient causation at the physical level and causation in virtue of irreducible mental properties, without any sort of problematic overdetermination. We can account for both the multiple realizability and the context dependence of many mental properties. And we can account for why mental explanations often seem to offer us better predictive and explanatory power than lower level physical ones. Mental explanations work because menial properties are causal properties. 

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