An Introduction to the Principles of Morals and Legislation

What it is

This is a book by Jeremy Bentham, printed in 1780 and first published in 1789. It is considered his most important theoretical work and the first major book on utilitarianism.

Why it matters

In this book Bentham argues that pleasure and pain are the only true guides to right and wrong, and he tries to build a whole system of law on that idea. He proposes a method for weighing pleasures and pains called the felicific calculus. A footnote in the book, asking whether animals can suffer rather than whether they can reason, became one of his most famous statements and influenced later thinking about animal welfare. The book shows how Bentham wanted both ethics and the legal system to be reorganised on rational, measurable grounds.

Look closer

• Why might Bentham have chosen to measure right and wrong by pleasure and pain rather than by religious or traditional rules?
• What does the footnote about animal suffering tell you about the limits of ideas about rights in Bentham's time?
• How might a law based on this 'calculus' be difficult to apply in real life?