When this work was first published in 1960, it immediately filled a void in Kant scholarship. It was the first study entirely devoted to Kant's Critique of Practical Reason and by far the most substantial commentary on it ever written. Included are sections that show the connection between Kant's ethical theory and contemporary action theory. This landmark in Western philosophical literature remains an indispensable aid to a complete understanding of Kant's philosophy for students and professional scholars alike. This Critique is the only writing in which Kant weaves his thoughts on practical reason into a unified argument. Beck offers a classic examination of this argument and expertly places it in the context of Kant's philosophy and of the moral philosophy of the eighteenth century.