Functionalism and property dualism are both physicalist theories of the mind in that they don't admit any substances other than physical substance.
Property dualism holds that mental states are non-reducible properties of physical brains. Functionalism says that mental states should be defined in terms of their functional roles as opposed to being identified with physical brain states.
I can't see any difference between these positions other than they are looking at slightly different aspects of the mind-body problem: Property dualism is looking at it from an ontological point of view, while functionalism is addressing the issue of causal relationships between metal states, brain states and behavior. In fact, it seems to me that functionalism is just a refinement of property dualism: mental states are properties irreducible to brain states, and these properties can be described by their functional relationship to other brain mental states and to behavior.
In both cases, the key point is: mental states can't be reduced to brain states and behavior, they are fundamentally anti-reductionist. Once ones dismisses reductive physicalism (i.e. identity theories of the mind), whether it is a dualist theory, a functionalist theory or some form of emergentism seems a matter of semantics.
Yet in the literature, functionalism and property dualism are frequently described as being in opposition to each other: Daniel Dennett for example is described as functionalist who is opposed to dualism (presumably including property dualism).
- What is the difference between property dualism and functionalism?
- Are there any specific points on which property dualism and functionalism are incompatible?
- More generally, how can we ever differentiate non-reductive physicalist theories and dualist theories?