Aspects of the new mechanical philosophy began to emerge in the late 1960s. Fodor (1968), for example, contrasted mechanistic explanations (dealing with parts and their law-like interactions) with functional explanations in psychology. Wimsatt (1972a, 1976), building on the work of Simon (1962) and Kaufman (1971), argued repeatedly that the abstract and idealized structures of logical empiricism were ill-suited to understanding how scientists discover and explain complex systems at multiple levels of organization. Cummins (1975) provided an account of functional analyses, characterizing a function as a contribution a component part makes to the overall capacity of some system that includes that component. Salmon (1984, 1989) argued that empiricist views of scientific explanation are fundamentally flawed because they neglect causal mechanisms. Cartwright (1989) argued that the logical empiricist conception of a law of nature is, in fact, a philosophical fiction used to describe the search for capacities and nomological machines.