A dilemma for the Russo–Williamson thesis

The Russo–Williamson thesis maintains that establishing a causal claim in medicine normally requires establishing both a correlation and a mechanism. In this paper, I present a dilemma for defenders of this thesis: a strong version of the thesis requires denying a plausible counterexample, but as the thesis is weakened, its defenders must give up their favoured account of the explanatory role of causal claims in medicine. I appeal to some recent work in epistemology on infallibilism to propose a way out of this dilemma, where this way out requires neither denying the plausible counterexample nor giving up the favoured account. I think this shows that even apparently abstract debates in epistemology can provide resources that may help to resolve debates in the philosophy of science and medicine.