Epiphenomenalism is the view that phenomenal properties – which characterize what it is like, or how it feels, for a subject to be in conscious states – have no physical effects. One of the earliest arguments against epiphenomenalism is the evolutionary argument (James 1890/1981; Eccles and Popper 1977; Popper 1978), which starts from the following problem: why is pain correlated with stimuli detrimental to survival and reproduction – such as suffocation, hunger and burning? And why is pleasure correlated with stimuli beneficial to survival and reproduction – such as eating and breathing? According to the argument, the fact that we have these particular correlations and not other ones must have an evolutionary explanation. But given epiphenomenalism, differences in phenomenal properties could not cause differences in fitness, so natural selection would not be expected to favor these correlations over any other ones. Epiphenomenalism thus renders these correlations an inexplicable coincidence, and should therefore be rejected.
The evolutionary argument has been widely criticized and few have deemed it cogent (Broad 1925; Jackson 1982; Robinson 2007; Corabi 2014). In this paper, I will consider previous and potential criticisms and conclude some of them are indeed fatal to the argument if it is understood, as it traditionally has been, as an argument for any standard version of non-epiphenomenalism such as physicalism and interactionism. I will then offer a new and improved version of the argument, as an argument for a particular non-epiphenomenalist view, which I will call the phenomenal powers view. This is the view that phenomenal properties produce and thereby (metaphysically) necessitate their effects in virtue of how they feel, or in virtue of their intrinsic, phenomenal character alone – along the lines of C. B. Martin and John Heil’s powerful qualities view (Martin and Heil 1999; Heil 2003). I will argue that the phenomenal powers view explains the correlations given natural selection far better than any other view. It follows that if (and only if) understood as an argument for the phenomenal powers view, the evolutionary argument is far stronger than it is usually thought to be.