How did Joseph Priestley influence Jeremy Bentham’s idea of the greatest happiness of the greatest number?

Jeremy Bentham, the founder of modern utilitarianism, explicitly acknowledged that his famous principle—the "greatest happiness of the greatest number"—was inspired by the writings of Joseph Priestley.12

Specifically, Bentham drew this inspiration from Priestley’s 1768 work, An Essay on the First Principles of Government. In this text, Priestley argued that the effectiveness of government should be evaluated solely based on the welfare of the individual. By advocating for a limited role for government and emphasizing that political and civil liberties—such as freedom of speech—were essential for human progress, Priestley provided a foundational framework that Bentham later adapted into his broader ethical and legislative system.21

While Bentham discovered the principle of utility through various 18th-century thinkers, including David Hume, Claude-Adrien Helvétius, and Cesare Beccaria, he specifically credited Priestley’s book with providing the iconic phrasing used to define his movement.12