Varieties of Egoism
Egoism is a teleological theory of ethics that sets as its goal the benefit, pleasure, or greatest good of the oneself alone. It is contrasted with altruism, which is not strictly self-interested, but includes in its goal the interests of others as well. There are at least three different ways in which the theory of egoism can be presented:
Psychological Egoism— This is the claim that humans by nature are motivated only by self-interest . Any act, no matter how altruistic it might seem, is actually motivated by some selfish desire of the agent (e.g., desire for reward, avoidance of guilt, personal happiness). This is a descriptive claim about human nature. Since the claim is universal–all acts are motivated by self interest–it could be proven false by a single counterexample.
It will be difficult to find an action that the psychological egoist will acknowledge as purely altruistic, however. There is almost always some benefit to ourselves in any action we choose. For example, if I helped my friend out of trouble, I may feel happy afterwards. But is that happiness the motive for my action or just a result of my action? The psychological egoist must demonstrate that the beneficial consequences of an action are actually the motivation of of all of our actions. But why would it make me happy to see my friend out of trouble if I didn't already care about my friend's best interest? Wouldn't that be altruism?
Ethical Egoism— This is the claim that individuals should always to act in their own best interest. It is a normative claim. If ethical egoism is true, that appears to imply that psychological egoism is false: there would be no point to saying that we ought to do what we must do by nature.
But if altruism is possible, why should it be avoided? Some writers suggest we all should focus our resources on satisfying our own interests, rather than those of others. Society will then be more efficient and this will better serve the interests of all. By referring to the interests of all, however, this approach reveals itself to be a version of utilitarianism, and not genuine egoism. It is merely a theory about how best to achieve the greatest good for the greatest number.
An alternative formulation of ethical egoism states that I ought to act in my own self-interest–even if this conflicts with the values and interests of others–simply because that is what I value most. It is not clear how an altruist could argue with such an individualistic ethical egoist, but it is also not clear that such an egoist should choose to argue with the altruist. Since the individualistic egoist believes that whatever serves his own interests is (morally) right, he will want everyone else to be altruistic. Otherwise they would not serve the egoist's interests! It seems that anyone who truly believed in individualistic ethical egoism could not promote the theory without inconsistency. Indeed, the self-interest of the egoist is best served by publicly claiming to be an altruist and thereby keeping everyone's good favor.
Minimalist Egoism— When working with certain economic or sociological models, we may frequently assume that people will act in such a way as to promote their own interests. This is not a normative claim and usually not even a descriptive claim. Instead it is a minimalist assumption used for certain calculations. If we assume only self-interest on the part of all agents, we can determine certain extreme-case (e.g., maximin) outcomes for the model. Implicit in this assumption, although not always stated, is the idea that altruistic behavior on the part of the agents, although not presupposed, would yield outcomes at least as good and probably better.