Sunday, November 25, 2007

Locke on gravity and mental properties

Mechanism, generally, is the view that all of the operations, interactions, and sensible qualities of natural bodies are causally dependent upon the mechanical qualities of those bodies. Laws which govern the behavior of the mechanical parts and properties can be explained by being deduced from the attributes possessed essentially by all bodies qua bodies.

The application of such a model of explanation to the relationship between mental and physical properties of fitly disposed systems of matter is of concern to the magisterial commentator on Locke, Michael Ayers. He motivates the query by comparison with how Locke viewed the phenomenon of gravity.

Locke took there to be something inexplicable to human observers about the relation between two bodies which accounted for gravitation. There are four ways of interpreting what Locke might take the inexplicability to imply:

(a) There is a deeper medium for a mechanism which creates a necessary connection which is not occult. The appearance of action at a distance is only an appearance.

(b) Knowledge of matter qua matter is not yet adequately refined to license perspicacious deductions of laws of nature from the mechanisms of matter. Such deductions are possible, in principle, but not with the present state of physics which is ignorant of the real essence of matter.

(c) There are some laws—viz., gravitation, that are not deducible from the essence of matter. Such laws depend on the direct, continuous, and systematic agency of God—viz., a continual miracle.

(d) Action at a distance turns out, after all, to be part of the real essence of matter—viz., mechanism is false after all.

While Locke’s views on gravity do not make it obvious which of the implications he embraces, Ayers thinks there is a clear case for Locke’s rejection of (d) in Locke’s correspondence with Stillingfleet, the Bishop of Worcester. Ayers ultimately takes Locke to accept either (b) or some combination of (a) and (b). In either case, the hope for a deduction of the laws of gravitation from the essence of matter is preserved, despite the epistemic limitations.

I think there is a similar dialectical structure present in the allegedly inexplicable connections between the mental and physical properties of fitly disposed systems of matter.

(i) There is a deeper medium for a mechanism which creates a necessary, non-occult connection between the fitly disposed physical properties and mental properties. The appearance of sui generis connections is only an appearance.

(ii) Knowledge of matter qua matter is not yet adequately refined to license perspicacious deductions of mental properties from the mechanical, fitly disposed physical properties of matter. Such deductions are possible, in principle, but not with the present state of physics which is ignorant of the real essence of fitly disposed matter.

(iii) There are some laws—viz., psychophysical laws, that are not deducible from the essence of matter. Such psychophysical laws depend on the direct, continuous, and systematic agency of God—viz., a continual miracle.

(iv) Occult, sui generis psychophysical laws turn out, after all, to be part of the real essence of matter—viz., mechanism is false after all.

For Locke to be a materialist, his position on thinking matter needs to reside somewhere between (i) and (ii).

Take M to be a fitly disposed material system.

(1) M thinks.

(2) M’s mental properties are deducible from M’s physical properties.

The challenge for Ayers is to argue that Locke affirms (2). The kind of deduction Ayers has in mind is a very strong sort. Assuming idealized epistemic conditions, where human cognizers know the real essence of matter and the real essence of fitly disposed material systems of kind M (i.e., they possessed wholly adequate concepts of matter), cognizers should be in a position to determine the necessity of mental properties arising from M’s particular arrangement of physical properties. What would be the form of such a deduction?

(3) There is a true description P of M’s real essence qua fitly disposed matter.

(4) Q.

(5) Therefore, M thinks.

The crucial premise is (4), where Q stands for a proposition which must discharge two duties—Q’s content must refer to the physical (primary) qualities of M, and Q must imply, in conjunction with P, the conclusion (5). In short, the deductions must be like geometric inferences.

For various reasons (which may end up in later posts), I'm seriously pessimistic that Locke would go this far.
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