The Closure Argument from A Great Divide

Yes.
Consciousness is epiphenomenal

Physical properties are not identical to mental properties (including, of course, conscious properties). Physical properties, or, better, a privileged subset of them, the basic ones, form a closed domain. The idea is that "....any physical event that has a cause at time t has a physical cause at time t. This is the assumption that if we trace the causal ancestry of a physical event, we need never go outside the physical domain" (Kim, 1989, p. 280). Predicting the course of a basic physical particle will not involve considering such things as what people in the vicinity are planning to have for dinner. Furthermore, since, given supervenience, all non-basic properties are determined by the basic properties (see left side of poster), those non-basic properties cannot, in turn, affect the basic ones. If they could, then we would have to invoke properties outside the realm of the basic properties to explain the occurrence of the latter. The basic laws of nature would be violable. Physicists do not have to worry about what psychologists are doing (though the converse may well not be true). Since consciousness supervenes on brain states, which themselves supervene (eventually) on states of basic particles, all the "real" work is being done at the level of basic physics. Therefore, consciousness is epiphenomenal.

Response:

What we explain in psychology is not mere bodily movement, but instead action and behaviour. We do not attempt to explain why, e.g., your left arm extended out the window (which is already a description at a far remove from basic physics!) but rather why you signalled to turn left. The laws of basic physics are not violated, of course, but they do not interest us in this context. Events described in the language of psychology require (usually, at least) explanations that appeal to other events described in the language of psychology. Such explanations are not just "rationalisations" of behaviour-they are causal explanations. However, they do not compete with explanations at the level of physics. (See, e.g., Davidson (1963), Marras (1998).)

The first response makes causal relations largely a matter of ascription. We can grant that explanations are interest-relative, but the bifurcated picture sketched deserves more of an answer. After all, we could have a "science" of astrology, provided the "properties" appealed to in such a science supervened on the properties of basic science and none of its "laws" required violating laws of the lower level. Instead, let's look at the consequences of the above austere view: causal claims about non-basic properties would be ruled out-e.g., claims about airfoils and rivers could not be, strictly speaking, causal. But this means that "meandering rivers tend to erode their banks" is false, and that is absurd and has nothing to do with the mental. (See Fodor (1989).)

On to next page, The Argument from Identity

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