An Introduction to the Principles of Morals and Legislation is a book by the English philosopher and legal theorist Jeremy Bentham "originally printed in 1780, and first published in 1789.

Like John Stuart Mill, whom he greatly influenced, Bentham believed that happiness or pleasure is the only thing that is good for its own sake.

In The Principles of Morals and Legislation, Bentham seeks to determine what a system of laws would look like if it was constructed on a purely utilitarian basis.

It may one day come to be recognized that the number of legs, the villosity of the skin, or the termination of the os sacrum are reasons equally insufficient for abandoning a sensitive being to the same fate.

"[4] The Introduction also contains Bentham's famous discussion of the "felicific (or hedonic) calculus"—his proposed method for determining which future course of action would produce the greatest net amount of pleasure over pain.