Immanuel Kant's Fundamental Principles of the Metaphysics of Morals, first published in 1785, lays out Kant's essential philosophy and defines the concepts and arguments that would shape his later work. Central to Kant's doctrine is the categorical imperative, which he defines as a mandate that human actions should always conform to a universal, unchanging standard of rational morality. Directly opposed to utilitarian philosophy, Kant's theories have been broadly influential since their publication and stand as a seminal contribution to ethical thought. Although Kant expanded upon the ideas defined here in his later work, including the Critique of Pure Reason and the Metaphysics of Morals, it is in his Fundamental Principles of the Metaphysics of Morals that they are communicated in their most clear, concise form. This edition is the translation by Thomas Kingsmill Abbott.