Daniel Crow

Two of the most prominent evolutionary debunking arguments are Sharon Street's Darwinian Dilemma for Normative Realism and Alvin Plantinga's Evolutionary Argument against Atheism. In the former, Street appeals to evolutionary considerations to debunk normative realism. In the latter, Plantinga appeals to similar considerations to debunk atheism. By a careful comparison of these two arguments, I develop a new strategy to help normative realists resist Street's debunking attempt. In her Darwinian Dilemma, Street makes epistemological commitments that ultimately support Plantinga's structurally similar argument. If Street succeeds in debunking normative realism, I argue, then she also succeeds in debunking atheism. But atheism is a suppressed premise of the Darwinian Dilemma as well as a commitment of almost all normative anti-realists. If Street's argument entails theism, then the Darwinian Dilemma is internally incoherent and should be abandoned by almost everyone.

Two epistemological critiques of non-naturalism are not always carefully distinguished. According to the Causal Objection, the fact that moral properties cannot cause our moral beliefs implies that it would be a coincidence if many of them were true. According to the Evolutionary Objection, the fact that evolutionary pressures have influenced our moral beliefs implies a similar coincidence. After distinguishing these epistemological critiques, I provide an extensive defense of the Causal Objection that also strengthens the Evolutionary Objection. In particular, I formulate a “Master Causal Objection” featuring the controversial premise that non-naturalism can provide no adequate explanation for moral knowledge. I defend this premise by first narrowing down the range of candidate explanations to conceptual, constitutive, and evolutionary explanations, and then considering and eliminating each of these in turn. My discussion of evolutionary explanations suggests that non-naturalists must refute the Causal Objection in order to refute the Evolutionary Objection.