Bentham
Jeremy Bentham looked at English law, found it a thicket of inherited fictions and cruelties that no one could explain or justify, and decided to throw the whole inheritance out and start from a single fact: human beings are run by pain and pleasure, and nothing else. From that one fact he built a machine for judging anything at all. An action, a punishment, a law, a whole government is good exactly to the degree that it adds up to more happiness than misery for everyone it touches, and that is the *only* thing that makes it good. The greatest happiness of the greatest number is the measure, and he meant *measure* literally: he laid out seven dimensions along which a pleasure or a pain can be weighed, and insisted that with enough care the sums could in principle be done. Against the grand talk of natural rights then shaking France he was merciless, calling such rights nonsense upon stilts, because a right that no actual law backs is just a wish dressed up as a fact. He carried the same standard places no one had carried it: to the prison, which he tried to redesign from the ground up as a tower of total visibility he called the Panopticon, and to animals, for whom he asked the question that reframed the whole debate about who counts, not can they reason but can they suffer. He was a reformer to the marrow, and he left his own corpse to the project. His skeleton, dressed and seated, still sits in a case at the university his circle built. Everything humane and everything chilling about counting happiness is already in him; his pupil [Mill](/philosophy/thinker/mill) spent a career trying to keep the humane and lose the chilling.