An ethical egoist believes that correct moral behaviour should be based solely on principles of self-interest. Ethical egoism is a philosophical argument that falls into the realm of ethical philosophy. Ethical philosophers attempt to develop a philosophically sound theory of morals that governs human action.
Ethical egoism is a normative or prescriptive philosophical view. It does not describe how people behave, rather, it describes how people "ought" to behave. Although this distinction might sound arbitrary, it is philosophically important. Normative philosophies prescribe certain types of correct behaviour that should be adhered to, regardless of the situation. This puts ethical egoists at a strong disadvantage because they hold what appears to be a contradictory position, according to philosophers such as G.E. Moore. Essentially, in a normative theory, something that is viewed as good must be universally viewed as good. Yet, an egoist would state that something is only good when he possesses it. It follows then, that the goodness of things would have to be circumstantial, not universal.
Ethical egoism differs from other ethical positions because it suggests that the interest of others should never be a factor in moral decision-making. An ethical egoist believes that self-sacrifice is not a moral action and that she should help others only insofar as it would offer her a tangible benefit in the long run. While this might offer the egoist short-term satisfaction, it could make her life worse in the long run because if everyone acted only in their own self-interests, then a society might develop in which people lived under constant threat of attack. A possibility is that this kind of society would lead to anarchy and fall apart, which benefits no one, including the egoist. Thus, a potential flaw or disadvantage of ethical egoism is that it could create a society that no one wants to live in and where nothing would ever get accomplished because everyone would be working against each other.
Most people would likely be uncomfortable with the kind of actions that ethical egoism prescribes. For example, if you saw a drowning child and could easily save them, an ethical egoist might state that you should only save the child if you would receive a personal benefit. For example, if a news crew were in the area and the rescue brought publicity, it might be worth it. However, if you were discomforted because you had to drive home in wet clothes for a long period, it might not be worth it. Another factor could be that you'd feel good because of the action you took, which could be construed as ethical behaviour by an ethical egoist.
When observing society, some philosophers state that ethical egoism is the closest philosophy to current practised moral behaviour. However, the goal of a moral philosophy is to form a basis for how people should act, not necessarily on how they actually behave. Moral philosophy aims to better the individual by prescribing the right set of behaviour, not merely to justify his current actions. To this end, some opponents of ethical egoism state that it cannot actually be viewed as a moral theory. If it is not in fact a moral theory, it doesn't hold weight in prescribing correct moral behaviour. If it is a correct moral theory, then proponents must justify the principles behind the theory. For it to be a sound moral theory, ethical egoists must demonstrate that theory is systematic, consistent and would create the best possible life. Further, ethical egoists would have to demonstrate that the theory is universal in that it can be applied as means to solve all ethical dilemmas.