Reduction in the Philosophy of Mind

This chapter argues for the relevance of the notion of reduction and the fruitfulness of the explication. The concept of reduction defined in the previous chapter is key to an understanding of the reduction-debate in the philosophy of mind. Reductive identity-theories, type-identity theories as well as token-identity theories, and models of functional reduction conceive of reduction precisely as described above: These theories are supposed to reconcile strong unity with diversity and directionality; according to this conception, a reduces to b only if a = b. Type-identity theories are underdetermined with respect to directionality; the proposal offered here fixes this deficiency in a natural way. Classical versions of type-identity theory can be interpreted in terms of the explication offered here. The idea that reduction is tied to conceptual diversity is pertinent in the writings of early type-identity theorists. The explication of reduction offered here also sheds light on more recent forms of type-identity theory, according to which type-identifications are achieved via contextualized kinds or via “disjunctive” kinds. Notions of token-reduction, type-reduction, and functional reduction can be defined within the present framework, and the doctrine of non-reductive physicalism can be characterized.