 Other important recent antecedents of functionalism are the behaviorist theories that emerged in the early-to-mid twentieth century. These include both the empirical psychological theories associated primarily with Watson and Skinner, and the “logical” or “analytical” behaviorism of philosophers such as Malcolm (1968) and Ryle (1949) (and, arguably, Wittgenstein 1953). Though functionalism is significantly different from behaviorism in that the latter attempts to explain behavior without any reference whatsoever to mental states and processes, the development of two important strains of functionalism, “psychofunctionalism” and “analytical” functionalism, can both be profitably viewed as attempts to rectify the difficulties, respectively, of empirical and logical behaviorism, while retaining certain important insights of those theories.