There are many ways of dividing up types of ethical theories. I have chosen to divide the traditions according to what they see as the basic question of ethics:
Most ethical theories attempt to answer the question of "How ought I to act?" Some, called consequentialists, answer that question by pointing to the consequences of our acts and weighing those consequences to determine how we ought to act in a particular situation. Other theories, called deontological theories, maintain that the anser to this question is simple: act in such a way that you are performing your duty.
Another major tradition in ethics sees the fundamental question to be one of character: "What kind of person ought I to be?" This tradition, rooted in Plato and Aristotle, sees good character as the source of good acts.
The philosopher Ayn Rand was undoubtedly the best known proponent of ethical egoism, the moral theory that maintains that I should always act in such a way as to benefit myself. In The Virtue of Selfishness, Rand even sees altruism--concern for the other, independent of ourselves--as a fatal flaw, as a moral failing. Through her novels such as Atlas Shrugged she expounded and furthered this point of view for a much wider audience than philosophers are usually able to reach.
Those who believe that the rightness or wrongness of an act depends on the consequences are called consequentialists. Generally speaking, consequentialism is divided into three main types, depending on who counts in weighing the consequences. If I am only considering the consequences for myself and no one else, then this is ethical egoism. If I am considering the consequences for myself and others within my group (country, religion, family, etc.), then this is group consequentialism. If I am considering the consequences for everyone, then this is utilitariainism. In its strong form, utlitarianism considers the consequences for all sentient beings; in its more modest form, it considers the consequences for all human beings.
The German philosopher Immanuel Kant maintained that being moral involves doing things just because they are right--in other words, doing things for the sake of duty. Moral worth only emerges when we set aside our feelings of vanity, sympathy, etc., and act solely because it is the right thing to do. For Kant, our duty is specified by reason itself as specified by what Kant calls the categorical imperative.
Aristotle believed that the best way to guarantee right actions was to insure that individual agents had a strong character, the virtues appropriate to the situation. He saw virtues as strengths of character necessary to human flourishing, and vices were weaknesses of character that would impede such flourishing. Cowardice, for example, is a vice because those who are cowards are unable to overcome their fears and thus prevented from achieving their goals.
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