This dissertation is a critique of synthetic ethical naturalism (SEN). SEN is a view in metaethics that comprises three key theses: first, there are moral properties and facts that are independent of the beliefs and attitudes of moral appraisers (moral realism); second, moral properties and facts are identical to (or constituted only by) natural properties and facts (ethical naturalism); and third, sentences used to assert identity or constitution relations between moral and natural properties are expressions of synthetic, a posteriori necessities. (...) The last of these theses, which distinguishes SEN from other forms of ethical naturalism, is supported by a fourth: the semantic contents of the central moral predicates such as 'morally right' and 'morally good' are fixed in part by features external to the minds of speakers (moral semantic externalism). Chapter 1 introduces SEN and discusses the most common motivations for accepting it. The next three chapters discuss the influential "Moral Twin Earth" argument against moral semantic externalism. In Chapter 2, I defend this argument from the charge that the thought experiment upon which it depends is defective. In Chapters 3 and 4, I consider two attempts to amend SEN so as to render it immune to the Moral Twin Earth argument. I show that each of these proposed amendments amounts to an abandonment of SEN. Chapter Five explores Richard Boyd's proposal that moral goodness is a "homeostatic property cluster." If true, Boyd's hypothesis could be used to support several metaphysical, epistemological, and semantic claims made on behalf of SEN. I advance three arguments against this account of moral goodness. In the sixth chapter, I argue that moral facts are not needed in the best a posteriori explanations of our moral beliefs and moral sensibility. Because of this, those who accept a metaphysical naturalism ought to deny the existence of such facts or else accept skepticism about moral knowledge. In Chapter 7, I consider a counterargument on behalf of SEN to the effect that moral facts are needed in order to explain the predictive success of our best moral theories. I show that this argument fails. (shrink)

In this paper I argue that the explanationist argument in favour of moral realism fails. According to this argument, the ability of putative moral properties to feature in good explanations provides strong evidence for, or entails, the metaphysical claims of moral realism. Some have rejected this argument by denying that moral explanations are ever good explanations. My criticism is different. I argue that even if we accept that moral explanations are (sometimes) good explanations the metaphysical claims of realism do not (...) follow. (shrink)

The main aim of this thesis is to defend moral realism. In chapter 1, I argue that moral realism is best understood as the view that moral sentences have truth-value, there are moral properties that make some moral sentences true, and moral properties are not reducible to non- moral properties. Realism is contrasted with non-cognitivism, error-theory and reductionism, which, in brief, deny, and, respectively. In the introductory chapter, it is also argued that there are some prima facie reasons to assume (...) that non-cognitivism and error-theory are erroneous. In chapters 2 and 3, I suggest that the two main forms of reductionism, analytic and synthetic reductionism, are mistaken. In chapter 4, I argue that the considerations in the previous chapters in relation to non-cognitivism, error-theory and reductionism provide support to moral realism. It is also suggested that these considerations make it plausible to hypothesise that moral properties depend on non- moral properties in a way I refer to as ‘the realist formula’. The realist formula confirms moral realism since it implies that moral properties are not reducible to non- moral properties. In chapters 5, 6 and 7, I argue that moral realism, much owing to the realist formula, is able to explain significant meta-ethical issues regarding moral disagreement, moral reason and moral motivation. Among other things, externalism concerning moral motivation is defended. The explanatory value of moral realism in relation to these meta-ethical issues is taken to suggest that this view is preferable to non-cognitivism, error-theory and reductionism. Some of the meta-ethical issues discussed in these chapters, particularly moral disagreement and motivation, have been thought to provide support to non-cognitivism and error-theory. I maintain that since realism, unlike reductionism, is able to counter these arguments, it justifies us in upholding the view that moral sentences have truth-value and the view that there are moral properties. In chapter 8, various objections against realism with regard to the dependence of moral properties on non- moral properties are responded to. In chapter 9, I consider an influential argument to the effect that moral properties are not involved in causal explanations. I maintain that this argument fails and that it therefore is reasonable to assume that moral properties are natural properties. However, the discussions in chapters 8 and 9 also suggest that moral realism might face problems that cannot be thoroughly discussed in this thesis. (shrink)

Though most of analytic philosophy is based upon intuitions, some philosophers are beginning to question whether intuitions are an appropriate basis for philosophical theory. This paper responds to the arguments of some contemporary philosophers who hold that intuitions should not be treated as evidence for anything other than our contingent psychological constitution. It begins with a demonstration that skeptical arguments by Gilbert Harman and Alvin Goldman are variations on an argument with the potential to undermine the use of intuitions in (...) much philosophical inquiry. After a demonstration that Nicholas Sturgeon’s response to Harman’s argument is inadequate, it argues that all of the instances of the skeptical argument are unsuccessful because they are epistemically self-defeating. (shrink)

Much moral skepticism stems from the charge that moral facts do not figure in causal explanations. However, philosophers committed to normative epistemological discourse (by which I mean our practice of evaluating beliefs as justified or unjustified, and so forth) are in no position to demand that normative facts serve such a role, since epistemic facts are causally impotent as well. I argue instead that pragmatic reasons can justify our continued participation in practices which, like morality and epistemology, do not serve (...) the function of causal explanation. Finally, I defend this pragmatic justification of morality and epistemology against a number of objections, including the objection that it confuses practical and theoretical justification. (shrink)

Many hope that our values, purged of messy human contingency, could aspire to correspond with mind-independent, rationally obligatory, and eternal ethical facts. But if the arguments of this thesis are on the right track, we should reject the search for non-natural and mind-independent moral truths.

Cornell realists maintain that irreducible moral properties have earned a place in our ontology in virtue of the indispensable role they play in a variety of explanations. These explanations can be divided into two groups: those that employ thin ethical concepts and those that employ thick ethical concepts. Recent work on thick concepts suggests that they are not inherently evaluative in their meaning. If correct, this creates problems for the moral explanations of Cornell realists, since the most persuasive moral explanations (...) are those that employ thick concepts. If thick concepts are not inherently evaluative, then the most plausible explanations on offer cannot support Cornell realism. Moral explanations employing thin concepts, however, are too flimsy to support the view. Unless proponents can develop a compelling story about thick concepts or thin explanations, Cornell realism is in trouble. (shrink)

What exactly is reasoning? Like many other philosophers, I shall endorse a broadly causal conception of reasoning. Reasoning is a causal process, in which one mental event (say, one’s accepting the conclusion of a certain argument) is caused by an antecedent mental event (say, one’s considering the premises of the argument). Just like causal accounts of action and causal accounts of perception, causal accounts of reasoning have to confront a version of what has come to be known as the problem (...) of deviant causal chains. In this paper, I shall propose an account of the nature of reasoning, incorporating a solution to the specific version of the deviant causal chains problem that arises for accounts of reasoning. One striking feature of my solution is that it requires that certain normative facts are causally efficacious. It might be thought that this feature will make my account incompatible with any plausibly naturalistic approach to understanding the mind. I shall argue that this is not so: my account of the nature of reasoning is quite compatible with plausible versions of naturalism. (shrink)

Discussion of moral explanation has reached an impasse, with proponents of contemporary ethical naturalism upholding the explanatory integrity of moral facts and properties, and opponents--including both antirealists and non-naturalistic realists--insisting that such robustly explanatory pretensions as moral theory has be explained away. I propose that the key to solving the problem lies in the question whether instances of moral properties are causally efficacious. It is argued that, given the truth of contemporary ethical naturalism, moral properties are causally efficacious if the (...) properties of the special sciences are. (shrink)

Discussion of moral explanation has reached animpasse, with proponents of contemporaryethical naturalism upholding the explanatoryintegrity of moral facts and properties, andopponents – including both anti-realists andnon-naturalistic realists – insisting thatsuch robustly explanatory pretensions as moraltheory has be explained away. I propose thatthe key to solving the problem lies in thequestion whether instances of moral propertiesare causally efficacious. It is argued that,given the truth of contemporary ethicalnaturalism, moral properties are causallyefficacious if the properties of the specialsciences are. Certain objections are rebuttedinvolving (...) the nature of causation, on the onehand, and putative special features of themoral realm, on the other. (shrink)

We elucidate the conditions under which any hypothesis is explanatorily relevant by analyzing several tests of explanatory relevance and explanations based on those tests. A new causal criterion of explanatory relevance is developed and defended. We show how the causal criterion succeeds in establishing, at the very least, a very strong presumption against moral facts.

I consider whether evolutionary explanations can debunk our moral beliefs. Most contemporary discussion in this area is centred on the question of whether debunking implications follow from our ability to explain elements of human morality in terms of natural selection, given that there has been no selection for true moral beliefs. By considering the most prominent arguments in the literature today, I offer reasons to think that debunking arguments of this kind fail. However, I argue that a successful evolutionary debunking (...) argument can be constructed by appeal to the suggestion that our moral outlook reflects arbitrary contingencies of our phylogeny, much as the horizontal orientation of the whale’s tail reflects its descent from terrestrial quadrupeds. An introductory chapter unpacks the question of whether evolutionary explanations can debunk our moral beliefs, offers a brief historical guide to the philosophical discussion surrounding it, and explains what I mean to contribute to this discussion. Thereafter follow six chapters and a conclusion. The six chapters are divided into three pairs. The first two chapters consider what contemporary scientific evidence can tell us about the evolutionary origins of morality and, in particular, to what extent the evidence speaks in favour of the claims on which debunking arguments rely. The next two chapters offer a critique of popular debunking arguments that are centred on the irrelevance of moral facts in natural selection explanations. The final chapters develop a novel argument for the claim that evolutionary explanations can undermine our moral beliefs insofar as they show that our moral outlook reflects arbitrary contingencies of our phylogeny. A conclusion summarizes my argument and sets out the key questions that arise in its wake. (shrink)

Many commentators suppose that morality, objectively construed, must possess a minimal sort of explanatory relevance if moral realism is to be plausible. To the extent that moral realists are unable to secure explanatory relevance for moral facts, moral realism faces a problem. Call this general objection an “explanatory objection” to moral realism. Despite the prevalence of explanatory objections in the literature, the connection between morality’s explanatory powers and moral realism’s truth is not clear. This paper considers several different reasons for (...) subjecting morality to explanatory scrutiny and concludes that none of them uncover a special or compelling explanatory problem for realism. In light of these difficulties, an alternative account of the connection between moral realism and moral explanation is developed. Not only does this account make sense of explanatory objections to realism, it turns out that realists may have the resources to defend themselves against this explanatory concern, properly understood. (shrink)