The cosmos of duty is not in chaos: A defense of the unity of practical reasons

My project here is to defend the Unity of Practical Reasons, the view that all practical reasons are comparable in terms of reason simpliciter . This view contrasts with Structural Reasons Pluralism—Structural Pluralism for short—which holds that practical reasons are comparable only within respective domains. In Chapter 1 I explicate both the Unity of Practical Reasons and Structural Reasons Pluralism and provide a brief history of these views in Western moral philosophy. In Chapter 2, I present what I take to be the strongest arguments in favor of Structural Pluralism, which are found in the work of Henry Sidgwick and David Copp. In Chapter 3, I offer my responses to those arguments. In Chapter 4, I present arguments against the chief semantic claim of Structural Pluralism and contend that can we at least understand the claim that there is an all-things-considered domain that is both comprehensive and normatively supreme. In Chapter 5, I argue against the chief metaphysical claim put forward by defenders of Structural Pluralism, and argue that we have decisive reason to believe in the existence of a comprehensive and normatively supreme domain. In Chapter 6, I present a second argument against Structural Pluralism based on a dilemma: is the correct account of Structural Reasons Pluralism restricted to a certain number of legitimate domains or completely unrestricted? One horn of the dilemma leads to absurdities, the other to the acceptance of an overarching domain of the sort Structural Pluralism denies, and hence to contradiction