Editing Psychological egoism (section)

==Foundations==
Beginning with ancient philosophy, [[Epicureanism]] claims humans live to maximize pleasure.<ref>O'Keefe, T. (2005)</ref> [[Epicurus#Pleasure as absence of suffering|Epicurus]] argued the theory of human behavior being motivated by pleasure alone is evidenced from infancy to adulthood. Humanity performs altruistic, honorable, and virtuous acts not for the sake of another or because of a moral code but rather to increase the well-being of the self.

In modern philosophy, [[Utilitarianism#Jeremy Bentham|Jeremy Bentham]] asserted, like Epicurus, that human behavior is governed by a need to increase pleasure and decrease pain.<ref>Jeremy Bentham (1789)</ref>  Bentham explicitly described what types and qualities of pain and pleasure exist, and how human motives are singularly explained using psychological hedonism.  Bentham attempted to quantify psychological hedonism. Bentham endeavored to find the ideal human behavior based on [[Felicific calculus|hedonic calculus]] or the measurement of relative gains and losses in pain and pleasure to determine the most pleasurable action a human could choose in a situation.

From an evolutionary perspective, [[Herbert Spencer]], a psychological egoist, argued that all animals primarily seek to survive and protect their lineage. Essentially, the need for the individual and for the individual's immediate family to live supersedes the others' need to live.<ref>Sweet, W (2004)</ref>  All species attempt to maximize their own chances of survival and, therefore, well-being.  Spencer asserted the best adapted creatures will have their pleasure levels outweigh their pain levels in their environments.  Thus, pleasure meant an animal was fulfilling its egoist goal of self survival, and pleasure would always be pursued because species constantly strive for survival.