Why be moral? According to constitutivism, there are features constitutive of agency, actual or ideal, the properties of which explain why moral norms are normative for us. I aim to investigate whether this idea is plausible. I start off critically. After defining constitutivism and outlining its attractions and problems (chapter 1), I discuss the theories of various features of agency that are supposed to ground morality according to the leading constitutivists in the literature. I find these theories wanting. They are (...) based on implausible assumptions about agency (chapter 2), and they fail to make sense of moral (and other) norms because the so-called shmagency objection, according to which we can shirk from our normative commitments by being ‘shmagents’ rather than agents, appears in new ways for them (chapter 3). Then I get more constructive. I defend a two-tiered form of constitutivism. The first tier captures practical rationality, and the second tier captures reasons for action. Starting with the first tier, I defend a Humean theory of agency (chapter 4) and add a principle of instrumental rationality to it (chapter 5). Appendices A and B supplement these chapters with replies to criticisms of the Humean picture. In chapters 6 and 7, I put this conception of agency to work to reach the second tier of the view. I start by defending a form of reasons internalism which treats practical reasons as grounded in the desires of ideal agents (chapter 6). Then I extend this theory to moral reasons, arguing – unexpectedly for a Humean – that we have universally prescriptive reasons to cooperate with other cooperative agents to satisfy our other respective desires (chapter 7). Hence, the constitutive features of ideal agency ground a morality of cooperation. I conclude by summarizing the case for constitutivism (chapter 8). (shrink)

A brief explanation and overview of constitutivism.