General Argument against Ethical Naturalism

Ethical naturalists argue that normative properties are, in some sense, nothing over and above natural properties. Some philosophers think that all forms of naturalism must fail. They present, what Jonathan Dancy calls, ‘Blockbuster arguments’, which they think rule out every kind of naturalism. In this thesis I argue that these arguments do not succeed. In the first two chapters, I argue that both analytic and synthetic naturalists have good responses to G.E. Moore’s open question argument. Derek Parfit, as well as other non-naturalists, have presented a number of supposedly separate arguments against naturalism which are not meant to rely on any considerations about meaning; I argue against these in chapters 3 and 4. Non-cognitivists argue that all descriptivist theories like naturalism fail to explain the necessary connection between normative judgements and motivation. I argue, in an oblique way, that the kind of motivational internalism needed to ground this argument is not a threat to naturalism in chapter 5. In chapter 6, I turn to what I take to be more serious problems for naturalists arising from Terry Horgan and Mark Timmons’ Moral Twin Earth thought experiments. I argue first that tackling these thought experiments is a problem that all major metaethical theories share. The fact that everyone needs to address these problems makes more palatable the responses I then go on to develop. First, I argue that we might be able to accommodate these cases if we accept that people can disagree even if the semantic content of their utterances are not logically inconsistent. Second, I argue that we can debunk the intuitions that Moral Twin Earth cases are supposed to pump. I end by summarising what I have argued in the thesis.