"The Critique of Practical Reason" is a philosophical work by Immanuel Kant, published in 1788. It explores the nature of moral reasoning and the principles that govern ethical behavior. Kant argues that true morality is grounded in rationality and that moral laws are universal, applying to all rational beings. In this work, Kant introduces the concept of the categorical imperative, a fundamental principle that dictates that one should act only according to maxims that can be universally applied. He emphasizes the importance of autonomy and the role of reason in making moral decisions, asserting that individuals have a duty to act in accordance with moral law.