Thursday, November 5, 2009

Michael Tooley on property dualism



Tooley believes that mental properties are not physical properties, but interact with and effect physical things like brains, human bodies, and thus, ultimately, things like the direction in which cars travel.

Conscious experience cannot be "reduced" to physical events in the same way that the behavior of an air conditioner can be completely reduced to and explained by the various events that go on in the machine.

Does this show that the properties are non-physical? Does it in fact follow from the fact that mental properties can "bump around" physical things, that they are really physical properties, despite our temptation to segregate them from those properties like mass, that we have no problem labeling as 'physical'?

More on this in a later post.

Update: More on this in the same post!

The list of properties usually considered physical includes things like mass, weight charge, chemical valence, molecular structure and composition, atomic weight, etc.. All the things that physicists and chemists can measure or observe using standard scientific techniques. Now, aside from these properties, we all would add that physical things have other properties, such as color, or odor, that can be explained by or reduced to some set of these fundamental physical properties. Red colored apples, for instance, are red because they have a molecular composition that absorbs most other wavelengths of visible light, and reflects frequencies that cause beings like ourselves to see them as red. So adding these secondary properties to the first bunch, most of us would have no problem labeling all of them as physical.

But, things are different with mental properties. Think now, not of the molecular structure of that apple, but of your experience of that structure, as mediated via your sense organs and nervous system. You have a peculiar experience, a sensation that you can only describe by demonstrative comparison to others similar to it. The thing you 'know' when you see the red apple is different than the thing that Mary the colorblind neuroscientist knows, when she writes her extremely detailed book concerning color perception. Yet you both can be truthfully described as "knowing" what red is. It just seems that you know more than she does. You know, by acquaintance, that the events she describes using the 3rd person language of science have as another aspect, a 1st person sensory phenomena of a certain type, for normal human beings, when appropriately staring at an apple. To use some terminology, you can see that this sort of experience 'emerges' from the situation I've just described.

Now, a reason that property dualists might say that these emergent 1st person sensory phenomena cannot be physical properties, is that, unlike other emergent properties that seem to be caused by and correlative with certain processes in complex physical things, we cannot break down the parts or stages in the complex process in such a way as to see how the resultant state or event emerges or falls out as an inevitable result, according to known natural laws.

To use the analogy mentioned earlier: An air conditioning system is able to control the temperature of an enclosed room, something that none of the parts of that system can do alone. This is an emergent property in the sense that it is something that comes about thanks to the collective of parts behaving as they normally do, in the particular articulation that they instantiate. One can, by examining the parts, and examining the particular construction, give a complete explanation of how it is that the air conditioner is able to control its environment.

We cannot do something like this with color sensations, or any other mental properties. The Mary case shows this. Unless you are directly acquainted with the first person results of the operations of neural structures you wouldn't have a clue that they result in just these sorts of sensations. (The 'these' here demonstrating to me and you the red sensations we all know I'm talking about)

Moreover, it doesn't look like we will ever be able to do this sort of thing. The best we can do is to note constant conjunctions of certain neural events with certain first person mental states, and that is as close as we can get to something like the air conditioning case.

So, since their is always this explanatory gap, the property dualist might conclude, mental states, or mental properties are not physical properties.

Problems for this view parallel problems that are traditionally held to pester substance dualism: How is it that a property that is not physical can interact with a physical property in such a way as to effect physical change?

Notice; this doesn't seem to be a problem when you consider two physical properties. Two electrically charged atoms can come together, precisely because the charges are physical properties. I can pick up my beer because my hand has physical properties that interact with similar properties in the glass.

How is a similar sort of story to go when you consider my will, intention, or desire to pick up that glass, and how it is that that mental property causes my neurons to fire, muscles to contract, etc..? How, that is, are you supposed to tell that story when you assume that my mental properties are not physical properties?

If, on the other hand, we accept that only physical properties can affect physical things in such ways, it seems we can argue, on that basis, in a straightforward fashion (modus ponens) that mental properties are indeed physical properties.

In fact this seems the more natural position for the property dualist to take given that he already believes that mental states are dependent for their existence on physical objects of certain complex sorts. It seems a borderline truism to assert that physical states of complex things are dependent upon the physical states of the things which constitute them. What is more, we can even admit that some physical properties of complex things are properties that those simples from which they are constructed can only come to have collectively, and might even be novel to that extent. An example is that air conditioner's ability to control. It has the property of controlling temperature only collectively, that's as near as its parts are going to get to being able to do that sort of thing. Similarly with liquidity and individual water molecules, according to an example of Searle's. So too, in conclusion, can it be for mental properties. They are emergent first person, or subjective physical properties that only collectives can have, and they are of a sort that are not reducible, in the way that non-subjective collective emergent properties are. But, that in no way diminishes their physicality.