See J. C. Gosling, Pleasure and Desire (1969).
Hedonism is the philosophy that pleasure is of ultimate importance, the most important pursuit. The name derives from the Greek word for "delight" (ἡδονισμός hēdonismos from ἡδονή hēdonē "pleasure", a cognate of English sweet + suffix ισμός ismos "ism").
Critics of the quantitative approach assert that, generally, "pleasures" do not necessarily share common traits besides the fact that they can be seen as "pleasurable." Critics of the qualitative approach argue that whether one pleasure is higher than another depends on factors other than how pleasurable it is. For example, the pleasure of sadism is a more base pleasure because it is morally unpalatable, and not because it is lacking in pleasure.
While some maintain that there is no standard for what constitutes pleasurable activities (for example, those with an interest in sadomasochism), most contemporary hedonists believe that pleasure and pain are easily distinguished and pursue the former.
In the medical sciences, the inability to derive pleasure from experiences that are typically considered pleasurable is referred to as anhedonia.
Cyrenaicism (4th and 3rd centuries B.C.), founded by Aristippus of Cyrene, was one of the earliest Socratic schools, and emphasized one side only of the Socratic teaching. Taking Socrates' assertion that happiness is one of the ends of moral action, Aristippus maintained that pleasure was the supreme good. He found bodily gratifications, which he considered more intense, preferable to mental pleasures. They also denied that we should defer immediate gratification for the sake of long-term gain. In these respects they differ from the Epicureans.
Epicureanism is considered by some to be a form of ancient hedonism. Epicurus identified pleasure with tranquillity and emphasized the reduction of desire over the immediate acquisition of pleasure. In this way, Epicureanism escapes the preceding objection: while pleasure and the highest good are equated, Epicurus claimed that the highest pleasure consists of a simple, moderate life spent with friends and in philosophical discussion.
However, hedonism is not necessarily related to egoism. The utilitarianism of John Stuart Mill is sometimes classified as a type of hedonism, as it judges the morality of actions by their consequent contributions to the greater good and happiness of all. This is altruistic hedonism. Whereas some hedonistic doctrines propose doing whatever makes an individual happiest (over the long run), Mill promotes actions which make everyone happy. Compare individualism and collectivism.
It is true that Epicurus recommends for us to pursue our own pleasure, but he never suggests we should live a selfish life which impedes others from getting to that same objective.
Some of Sigmund Freud's theories of human motivation have been called psychological hedonism; his "life instinct" is essentially the observation that people will pursue pleasure. However, he introduces extra complexities with various other mechanisms, such as the "death instinct". The death instinct, Thanatos, can be equated to the desire for silence and peace, for calm and darkness, which causes them another form of happiness. It is also a death instinct, thus it can also be the desire for death. The fact that he leaves out the instinct to survive as a primary motivator, and that his hypotheses are notoriously invalidated by objective testing, casts doubt on this theory.
Ayn Rand, one of the biggest modern proponents of Egoism, rejected hedonism in a literal sense as a comprehensive ethical system: