 Boorse’s position has been very influential and shaped the entire recent literature. Williams (2007) retains the spirit of the proposal but departs from it in arguing that disease is realized not in systemic malfunctions but failures of interacting cellular networks; he regards applications of disease language to organs, for example, as not strictly speaking correct. Most theorists, though, have continued to emphasis malfunction in physiological mechanisms more broadly. In psychiatry, for instance, Wakefield (1992, 1997a, 1997b), follows Boorse (1976) in assuming that humans have a species-typical design, which he assumes is a product of natural selection. Wakefield applies the picture to both mental and physical illness: in Wakefield’s version we first judge that a psychological mechanism is not performing the function for which natural selection designed it; second, we judge that the malfunction is harmful. An appeal to natural function, by adding extra commitments to the idea of a cause of illness, rules out skin pigment as a cause of evil.