Abstract

The thesis is a critical and comprehensive examination of Immanuel Kant's theory of practical reason. I argue that considerable light is thrown upon Kant's view when it is considered in light of the British naturalist ethics stretching from Hobbes to Hutcheson, and especially Hume. Consideration of the naturalist ethics is important because of that tradition's radical skepticism about the power of pure practical reason. While not many scholars emhasize this point, Kant's ethics is not so much a response to amoralism as a response to naturalism about practical reason. Such naturalism is pernicious on Kant's view because it undermines the universality, and accordingly the necessity, of moral claims. It is from this perspective that I examine Kant's views on instrumental reasoning, moral reasoning, justification of the moral law and freedom, and the doctrine of the unity of reason. ;I begin with a short introduction in which I discuss and illuminate the importance of the British empirical-naturalist ethics for Kant's system. ;In Chapter I, I explore Kant's theory of instrumental reasoning. By extensively discussing Kant's account of the hypothetical imperative, I show that Kant's general theory of practical reasoning cannot be fully appreciated apart from an understanding of the hypothetical imperative. ;In Chapter II, I discuss Kant's theory of moral reasoning. I first introduce Hume's moral psychology as background, and then discuss Kant's "transcendental psychology" of morality. I then examine his view of the categorical imperative in this light. ;In Chapter III, I critically examine Kant's various attempts to authenticate the moral law and freedom. ;Chapter IV consists of a reconstruction of Kant's overall response to Humean skepticism about pure practical reason--in particular, Kant's thesis of the unity of reason. Kant's claim that reason is not merely instrumental but capable of self-legislation seems to suggest that Humean skepticism about the power of pure practical reason is misguided. Kant thus seems to provide the means by which to combat naturalist skepticism about the power of pure practical reason.