Evolution and Ethics: No Streetian Debunking of Moral Realism

This paper is concerned with the reconstruction of a core argument that can be extracted from Street’s ‘Darwinian Dilemma’ and that is intended to ‘debunk’ moral realism by appeal to evolution. The argument, which is best taken to have the form of an undermining defeater argument, fails, I argue. A simple, first formulation is rejected as a non sequitur, due to not distinguishing between the evolutionary process that influences moral attitudes and the cognitive system generating moral attitudes. Reformulations that respect the distinction and that could make the argument valid, however, bring in an implausible premise about an implication from evolutionary influence to unreliability. Crucially, perception provides a counterexample, and the fitness contribution of reliably accurate representation has to be taken into account. Then the moral realist can explain why and how evolution indirectly cares for the truth of moral attitudes. The one and only condition that has to be satisfied in order for this explanation to work is the sufficient epistemic accessibility of moral facts. As long as the moral facts are sufficiently reliably representable, one can see how evolution could favor getting it right about the moral facts. Interestingly, apart from this epistemic constraint no further constraint and, in particular, no objectivity constraint on what the moral facts have to be like can be derived. Thus, the only problem for the moral realist is to make good on epistemic access to moral facts—an old problem, not a new one