Saturday, August 21, 2010

David Chalmers: Consciousness is not substrate dependent

A popular argument against uploads and whole brain emulation is that consciousness is somehow rooted in the physical, biological realm. Back in 1995, philosopher David Chalmers addressed this problem in his seminal paper, "Absent Qualia, Fading Qualia, Dancing Qualia." His abstract reads,
It is widely accepted that conscious experience has a physical basis. That is, the properties of experience (phenomenal properties, or qualia) systematically depend on physical properties according to some lawful relation. There are two key questions about this relation. The first concerns the strength of the laws: are they logically or metaphysically necessary, so that consciousness is nothing "over and above" the underlying physical process, or are they merely contingent laws like the law of gravity? This question about the strength of the psychophysical link is the basis for debates over physicalism and property dualism. The second question concerns the shape of the laws: precisely how do phenomenal properties depend on physical properties? What sort of physical properties enter into the laws' antecedents, for instance; consequently, what sort of physical systems can give rise to conscious experience? It is this second question that I address in this paper.
Chalmers sets up a series of arguments and thought experiments which point to the conclusion that functional organization suffices for conscious experience, what he calls nonreductive functionalism. He argues that conscious experience is determined by functional organization without necessarily being reducible to functional organization. This bodes well for the AI and whole brain emulation camp.

Chalmers concludes:
In any case, the conclusion is a strong one. It tells us that systems that duplicate our functional organization will be conscious even if they are made of silicon, constructed out of water-pipes, or instantiated in an entire population. The arguments in this paper can thus be seen as offering support to some of the ambitions of artificial intelligence. The arguments also make progress in constraining the principles in virtue of which consciousness depends on the physical. If successful, they show that biochemical and other non-organizational properties are at best indirectly relevant to the instantiation of experience, relevant only insofar as they play a role in determining functional organization.

Of course, the principle of organizational invariance is not the last word in constructing a theory of conscious experience. There are many unanswered questions: we would like to know just what sort of organization gives rise to experience, and what sort of experience we should expect a given organization to give rise to. Further, the principle is not cast at the right level to be a truly fundamental theory of consciousness; eventually, we would like to construct a fundamental theory that has the principle as a consequence. In the meantime, the principle acts as a strong constraint on an ultimate theory.
Entire paper.

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