 Ancient theories of the soul gave rise to debates among Aristotle’s successors that have a strong resemblance to some contemporary discussions of the efficacy of mental events (Caston, 1997). The modern discussion of epiphenomenalism, however, traces back to a 19th century context, in which a dualistic view of mental events was assumed to be correct. The first part of our discussion — Traditional Arguments — will be phrased in a style that reflects this dualistic presupposition. By contrast, many contemporary discussions work within a background assumption of the preferability of materialist monism. One might have supposed that this position would have put an end to the need to investigate epiphenomenalism; but, as we shall see under Arguments in the Age of Materialism, such a supposition is far from being the case. A brief outline of both discussions follows.