Psychological hedonism is the theory that all human choice is motivated by a desire

Desire (emotion)

Desire is a sense of longing for a person or object or hoping for an outcome. Desire is the fire that sets action aflame. The same sense is expressed by emotions such as "craving" or "hankering". When a person desires something or someone, their sense of longing is excited by the enjoyment or the...

 for pleasure

Pleasure

Pleasure describes the broad class of mental states that humans and other animals experience as positive, enjoyable, or worth seeking. It includes more specific mental states such as happiness, entertainment, enjoyment, ecstasy, and euphoria...

 (or an aversion to suffering

Suffering

Suffering, or pain in a broad sense, is an individual's basic affective experience of unpleasantness and aversion associated with harm or threat of harm. Suffering may be qualified as physical or mental. It may come in all degrees of intensity, from mild to intolerable. Factors of duration and...

).

This theory of human motivation cannot rule out altruism

Altruism

Altruism is a concern for the welfare of others. It is a traditional virtue in many cultures, and a core aspect of various religious traditions, though the concept of 'others' toward whom concern should be directed can vary among cultures and religions. Altruism is the opposite of...

 without being contradicted by evidence. Rather, it claims that when sane people choose to help others, it is because of the pleasure they themselves obtain, directly or indirectly, from doing so. Psychological hedonism is a special case of psychological egoism

Psychological egoism

Psychological egoism is the view that humans are always motivated by self-interest, even in what seem to be acts of altruism. It claims that, when people choose to help others, they do so ultimately because of the personal benefits that they themselves expect to obtain, directly or indirectly,...

, in which the concept of "self interest" is equated with pleasure.

All the arguments and counter-arguments presented in the article on psychological egoism

Psychological egoism

Psychological egoism is the view that humans are always motivated by self-interest, even in what seem to be acts of altruism. It claims that, when people choose to help others, they do so ultimately because of the personal benefits that they themselves expect to obtain, directly or indirectly,...

 also apply to psychological hedonism.

See also: Hedonism

Hedonism

Hedonism is a school of thought which argues that pleasure is the only intrinsic good. In very simple terms, a hedonist strives to maximize net pleasure .-Etymology:The name derives from the Greek word for "delight" ....