Abstract

Allen Buchanan and Russell Powell have developed a rich ‘biocultural theory’ of the nature and causes of moral progress (and regress) for human beings conceived as evolved rational creatures with a nature characterized by ‘adaptive plasticity’. They characterize their theory as a thoroughly naturalistic account of moral progress, while bracketing various questions in moral theory and metaethics in favor of focusing on a certain range of more scientifically tractable questions under some stipulated moral and metaethical assumptions. While I am very much in agreement with the substance of their project, I wish to query and raise some difficulties for the way it is framed, particularly in connection with the claim of naturalism. While their project is clearly naturalistic in certain senses, it is far from clear that it is so in others that are of particular interest in moral philosophy, and these issues need to be more carefully sorted out. For everything that has been argued in the book, the theory on offer may be only a naturalistic component of a larger theory that must ultimately be non-naturalistic in order to deliver the robust sort of account that is desired. Indeed, there are significant metaethical reasons for believing this to be the case. Moreover, if it turns out that some of the assumptions upon which their theory relies require a non-naturalist metaethics (positing irreducibly evaluative or normative properties and facts) then even the part of the theory that might have seemed most obviously naturalistic, i.e., the explanation of how changes in moral belief and behavior have come about, may actually require some appeal to non-naturalistic elements in the end.