The "Critique of Practical Reason" is a philosophical work by Immanuel Kant, published in 1788. It focuses on moral philosophy and explores the nature of human reason in relation to ethical decision-making. Kant argues that practical reason is essential for understanding moral laws and emphasizes the importance of duty and the categorical imperative in guiding moral actions. In this work, Kant distinguishes between theoretical and practical reason, asserting that while theoretical reason deals with knowledge and understanding, practical reason is concerned with action and morality. He aims to establish a foundation for ethics based on rationality, asserting that moral principles must be universally applicable to all rational beings.