This document discusses utilitarianism and its different types. It provides an overview of the key thinkers in utilitarianism including Jeremy Bentham, David Hume, Francis Hutcheson, and John Stuart Mill. It describes Bentham's concept of the greatest happiness principle and his hedonic calculus. It then discusses act utilitarianism versus rule utilitarianism and John Stuart Mill's modifications to utilitarianism which distinguished between higher and lower pleasures. The document applies utilitarian theory to different cases and discusses criticisms of utilitarianism.