Part I History of Ethics
Life of Socrates
Part II Concepts and Problems
Normative Ethics and Applied Ethics
Part III Applied Ethics
Field of Applied Ethics
Psychological and Ethical Egoism
As a metaethical theory of motivation, psychological egoism asserts the descriptive claim that all of our actions can be reduced to self-interest: "Whenever people do something, it is only because they think something desirable for themselves will result from it." The claim is descriptive and thus open to counterexamples, and it is broad, stating a reductionistic thesis regarding all of our actions. (Contrast psychological egoism with the psychological state of sympathy, where 'the weal and woe of the other becomes the motive for our action'.)
It is interesting to note that while egoism rests on the principles of human psychology, a number of studies in the psychology of moral development seem to suggest that 'egoism' is in fact only a first stage in actual moral development.Ethical egoism is a normative theory that states that our actions ought to be done from the perspective of self-interest. One of the problems with this position is that it might not be in one's self-interest to have eveyone act from the perspective of self-interest. This 'state of nature' would not be desirable (in Hobbes' terms, life would be "beastly, brutal, and short") and so it might ultimately be in one's self-interest to enter into a contract with others that would place restraints upon self-interested actions.
See excerpts from the Routledge Encyclopedia of Philosophy article on Egoism.