Abstract

The aim of this dissertation is to show that, if one is committed to the scientific worldview, one is thereby committed to ethical non-naturalism. In the first chapter I offer the reader an outline of the three primary domains of ethical inquiry: normative ethics, applied ethics, and meta-ethics. I commit myself to a meta-ethical thesis--ethical non-naturalism--and contrast ethical non-naturalism with its competitors. In the second chapter I offer a cursory defense of the moral realist's semantic thesis. I offer reason to think the realist has the correct semantic account and argue against the semantic accounts offered by the realist's primary opponents. In the third chapter of the dissertation I argue that commitment to the scientific worldview requires that one think that the methods of the sciences provide privileged access to facts about the external world and I offer a brief sketch of inference to the best explanation--the primary method I will employ in offering a defense of ethical non-naturalism. In the fourth chapter I develop a method for identifying non-natural properties. The method relies heavily on the predictive power that can be gained by the accurate application of predicates. In the fifth chapter I apply the method developed in the previous chapter. The results are mixed. The method fails to demonstrate that there are non-natural moral facts; however, it does demonstrate that there are non-natural normative facts. Using this result as a lemma, I identify a hypothesis--"[H]"--that, if true, would vindicate ethical non-naturalism. In the sixth chapter I rely on [H] to respond to evolutionary criticisms of ethical non-naturalism and argue that, if morality evolved, we have good reason to believe [H]. In the final chapter, I defend the view I have developed from objections arising from the existence of moral disagreement and I argue that [H] provides the best explanation of the existence of actual moral disagreement.