This book investigates the claim that there can only be one principle of morality, the categorical imperative.At the core of Kant's ethics lies the claim that if there is a supreme principle of morality then it cannot be based on utilitarian or Aristotelian perfectionism or the Ten Commandments. The only viable candidate for such principle is the categorical imperative. This book is the most detailed investigation of this claim. It constructs a criterial reading of Kant's derivation of one version of that imperative: the Formula of Universal Law. It also reveals a novel approach to deriving another version of the categorical imperative, the Formula of Humanity.At the core of Kant's ethics lies the claim that if there is a supreme principle of morality then it cannot be based on utilitarian or Aristotelian perfectionism or the Ten Commandments. The only viable candidate for such principle is the categorical imperative. This book is the most detailed investigation of this claim. It constructs a criterial reading of Kant's derivation of one version of that imperative: the Formula of Universal Law. It also reveals a novel approach to deriving another version of the categorical imperative, the Formula of Humanity.At the core of Kant's ethics lies the claim that if there is a supreme principle of morality, then it is not a utilitarian or Aristotelian perfectionist principle, or even a principle resembling the Ten Commandments. The only viable candidate for the supreme principle of morality is the Categorial Imperative. This book is the most detailed investigation of thie claim. It constructs a new, criterial reading of Kant's derivation of one version of the Categorial Imperative: The Formula of Universal Law. This reading shows this derivation to be far more compelling than contemporary philosophers tend to believe. It also reveals a novel approach to deriving another version of the Categorial Imperative, the Formula of Humanity, a principle widely considered to bel“#