Evolution and Utilitarianism

Katarzyna de Lazari-Radek and Peter Singer have recently provided an evolutionary argument for utilitarianism. They argue that most of our deontological beliefs were shaped by evolution, from which they conclude that these beliefs are unjustified. By contrast, they maintain that the utilitarian belief that everyone's well-being matters equally is immune to such debunking arguments because it wasn't similarly influenced. However, Guy Kahane remarks that this belief lacks substantial content unless it is paired with an account of well-being, and he adds that utilitarian beliefs about wellbeing e.g. the belief that pleasure is good and pain is bad- were probably shaped by evolution. Logically, de Lazari-Radek and Singer should therefore reject these beliefs along with the deontological beliefs that evolved. The present paper is a defense of their argument. After considering a number of unsuccessful replies to Kahane's objection, I put forward a more promising solution: de Lazari-Radek and Singer should combine their objectivist view in metaethics with a subjectivist account of well-being, such as the desire theory. Such a hybrid account would tackle Kahane's challenge because subjective accounts of value are immune from evolutionary debunking arguments. And it would be compatible with utilitarianism, which (as Kahane remarks) doesn't fit very well with metaethical subjectivism. Before concluding, I deal with two concerns that this solution might raise: I argue that the desire theory is actually subjective enough to escape Kahane's objection, and I deny that retreating to the combination of ethical objectivism and prudential subjectivism is ad hoc.