 Beyond this apparent tension between ideals of reduction and the reality of scientific diversification, pluralist philosophers emphasized the difficulties of applying reductionist frameworks. For example, consider the assumption that psychological theories reduce to biological theories or the related metaphysical claim that cognitive processes are ultimately nothing but brain processes. How can such a reductionism accommodate the development of artificial intelligence and the idea that cognitive processes could also be realized in systems that are not constituted by organic compounds at all? How can it accommodate the evolution of biological species with very different brain architectures or even the possibility of life on other planets that realize cognitive processes in radically different ways? This problem of “multiple realization” (R. C. Richardson 2009) did not merely appear in the cognitive sciences but also extends to other fields such as economics. For example, a generalization in economics may provide interesting insights about patterns in the social world but not correspond to unified physical generalizations or even strict physical laws. According to Fodor (1974), economic events can be realized through vastly different structures “whose physical descriptions have nothing in common” (1974: 103) and the reductionist program of unification at the level of microphysics is therefore doomed to fail.