  This principle enjoys wide support in the literature. It is said that postulating systematic overdetermination in this context is “absurd” (Kim 1993a, p. 281), one of the “nonstarters” in the mental causation debate (Kim 1998, p. 65). But why? Perhaps it just looks like bad engineering (Schiffer 1987, p. 148). Or maybe the problem is that it would involve an “intolerable coincidence” (Melnyk 2003, p. 291): every time you act, there are two independent causal processes—one from your brain, another from your soul—converging on the same effect.