Concerns the apparent antinomy between freedom and reason. Rationality appears to be a restraint on freedom, whereas freedom seems to be incompatible with rationality. Rejecting rationality to preserve freedom is the mark of subjectivist/emotivist theories of ethics. Rejecting freedom to emphasize rationality belongs to the naturalist/descriptivist theories. This book aims to reconcile these positions and do away with the alleged antinomy. The argument makes three main assumptions: (1) moral judgements are prescriptive; (2) they are universalizable; (3) there are genuine logical relations between prescriptive judgements. Insofar as moral judgements are universalizable, rationality gets a foothold, and their prescriptivity is intimately related to freedom to form one's own moral judgements. The first part of the book elaborates the thesis of universalizability and the connection between this feature and the fact that moral judgements have a descriptive element in addition to being prescriptive. The second and third parts expound the beginnings of a theory of moral reasoning grounded in the logic of prescriptivity and universalizability.