Ethical egoism is the normative ethical position that moral agents ought to do what is in their own self-interest. It differs from psychological egoism, which claims that people can only act in their self-interest. Ethical egoism also differs from rational egoism, which holds that it is rational to act in one's self-interest.
(http://en.wikipedia.org/wiki/Ethical_egoism)
There are three types of egoism which are?
1. Psychological Egoism
2. Ethical Egoism
3. Rational Egoism
1.Psychological Egoism
Psychological egoism claims that each person has but one ultimate aim: her own welfare. This allows for action that fails to maximize perceived self-interest, but rules out the sort of behavior psychological egoists like to target such as altruistic behavior or motivation by thoughts of duty alone. It allows for weakness of will, since in weakness of will cases I am still aiming at my own welfare; I am weak in that I do not act as I aim. And it allows for aiming at things other than one's welfare, such as helping others, where these things are a means to one's welfare.
Psychological egoism is supported by our frequent observation of self-interested behavior. Apparently altruistic action is often revealed to be self-interested. And we typically motivate people by appealing to their self-interest (through, for example, punishments and rewards).
2. Ethical Egoism
Ethical egoism claims that it is necessary and sufficient for an action to be morally right that it maximize one's self-interest. There are possibilities other than maximization. One might, for example, claim that one have to achieve a certain level of welfare, but that there is no requirement to achieve more. Ethical egoism might also apply to things other than acts, such as rules or character traits. Since these variants are uncommon, and the arguments for and against them are largely the same as those concerning the standard version, we set them aside.
3. Rational Egoism
Rational egoism claims that it is necessary and sufficient for an action to be rational that it maximize one's self-interest. As with ethical egoism, there are variants which drop maximization or evaluate rules or character traits rather than actions. There are also variants which make the maximization of self-interest necessary but not sufficient, or sufficient but not necessary, for an action to be rational. Again, we set these aside.
Like ethical egoism, rational egoism needs arguments to support it. One might cite our most confident judgments about rational action and claim that rational egoism best fits these. The problem is that our most confident judgments about rational action seem to be captured by a different, extremely popular theory the instrumental theory of rationality. According to the instrumental theory, it is necessary and sufficient, for an action to be rational, that it maximize the satisfaction of one's preferences. Since psychological egoism seems false, it may be rational for me to make an uncompensated sacrifice for the sake of others, for this may be what, on balance, best satisfies my (strong, non-self-interested) preferences. This conflict with the instrumental theory is a major problem for rational egoism.
The rational egoist might reply that the instrumental theory is equally a problem for any standard moral theory that claims to give an account of what one ought rationally, or all things considered, to do. If, for example, a utilitarian claims that I have most reason to give to charity, since that maximizes the general happiness, I could object that giving to charity cannot be rational given my particular preferences, which are for things other than the general happiness.
Conclusion
Prospects for psychological egoism are dim. Even if some version escapes recent empirical arguments, there seems little reason, once the traditional philosophical confusions have been noted, for thinking it is true. At best it is a logical possibility, like some forms of scepticism.
Ethical egoists do best by defending rational egoism instead.
Rational egoism faces objections from arbitrariness, Nagel and Parfit. These worries are not decisive. Given this, and given the historical popularity of rational egoism, one might conclude that it must be taken seriously. But there is at least reason to doubt the historical record. Some philosophers stressed the connection beween moral action and self-interest because they were concerned with motivation. It does not follow that self-interest is for them a normative standard. And many philosophers may have espoused rational egoism while thinking that God ensured that acting morally maximized one's self-interest.
"Some were keen to stress that virtue must pay in order to give God a role. Once this belief is dropped, it is not so clear what they would have said."
(Shaver 1999 ch. 4).(Shaver, R. 1999, Rational Egoism, Cambridge: Cambridge University Press.)