  The word ‘hedonism’ comes from the ancient Greek for ‘pleasure’. Psychological or motivational hedonism claims that only pleasure or pain motivates us. Ethical or evaluative hedonism claims that only pleasure has worth or value and only pain or displeasure has disvalue or the opposite of worth. Jeremy Bentham asserted both psychological and ethical hedonism with the first two sentences of his book An Introduction to the Principles of Morals and Legislation: “Nature has placed mankind under the governance of two sovereign masters, pain, and pleasure. It is for them alone to point out what we ought to do, as well as to determine what we shall do”. Debate about hedonism was a feature too of many centuries before Bentham, and this has also continued after him. Other key contributors to debate over hedonism include Plato, Aristotle, Epicurus, Aquinas, Butler, Hume, Mill, Nietzsche, Brentano, Sidgwick, Moore, Ross, Broad, Ryle and Chisholm.