Beginning the 1960s Hilary Putnam, Jerry Fodor, and Richard Boyd, among others, developed a type of materialism that denies reductionist claims. In this view, explanations, natural kinds, and properties in psychology do not reduce to counterparts in more basic sciences, such as neurophysiology or physics (Putnam 1967, 1974; Fodor 1974; Boyd 1980a). Nevertheless, all token psychological entities—states, processes, and faculties—are either identical with (Fodor 1974) or just wholly constituted of (Boyd 1980a) physical entities, ultimately out of token entities over which microphysics quantifies. This view was soon widely endorsed and since then has persisted as an attractive alternative to reductionist and eliminativist forms of materialism. Reductionists, notably Jaegwon Kim, have raised a series of serious objections to this position, to which nonreductivists have responded, thereby developing the view more thoroughly.

Irreducibility, Multiple Realizability, and Explanation

In his early argument for nonreductive materialism, Putnam adduces the phenomenon of multiple...