Is morality a subjective matter, dependent on our desires and interests, or are there objective moral truths? And if the latter, can we explain the objectivity of morality without appeal to metaphysics, a robust teleology, or divine command? This book argues that we find just such an account of moral objectivity in Thomas Reid's defence of duty. To make this case, this book provides an explanation of Reid's way of philosophy and his reasons for rejecting moral subjectivism; presents Reid's account of the concept, perception, and motivational force of duty; and responds to contemporary challenges of moral subjectivism and moral pessimism from the perspective of his moral philosophy. Further, this book argues that if Reid is correct, then there is an urgent need to reform current pedagogical practice and return to the teaching of practical ethics.