I'm not a big fan of Ayn Rand--I think her stance on charity is pretty heartless, and I didn't like her anti-religion stance, but this excerpt--from a 1964 Playboy interview struck me, and I tend to agree completely:
PLAYBOY: In Atlas Shrugged, one of your leading characters is asked, "What's the most depraved type of human being?" His reply is surprising: He doesn't say a sadist or a murderer or a sex maniac or a dictator; he says, "The man without a purpose." Yet most people seem to go through their lives without a clearly defined purpose. Do you regard them as depraved?
RAND: Yes, to a certain extent.
RAND: Because that aspect of their character lies at the root of and causes all the evils which you mentioned in your question. Sadism, dictatorship, any form of evil, is the consequence of a man's evasion of reality. A consequence of his failure to think. The man without a purpose is a man who drifts at the mercy of random feelings or unidentified urges and is capable of any evil, because he is totally out of control of his own life. In order to be in control of your life, you have to have a purpose -- a productive purpose.
PLAYBOY: Weren't Hitler and Stalin, to name two tyrants, in control of their own lives, and didn't they have a clear purpose?
RAND: Certainly not. Observe that both of them ended as literal psychotics. They were men who lacked self-esteem and, therefore, hated all of existence. Their psychology, in effect, is summarized in Atlas Shrugged by the character of James Taggart. The man who has no purpose, but has to act, acts to destroy others. That is not the same thing as a productive or creative purpose.
PLAYBOY: If a person organizes his life around a single, neatly defined purpose, isn't he in danger of becoming extremely narrow in his horizons?
RAND: Quite the contrary. A central purpose serves to integrate all the other concerns of a man's life. It establishes the hierarchy, the relative importance, of his values, it saves him from pointless inner conflicts, it permits him to enjoy life on a wide scale and to carry that enjoyment into any area open to his mind; whereas a man without a purpose is lost in chaos. He does not know what his values are. He does not know how to judge. He cannot tell what is or is not important to him, and, therefore, he drifts helplessly at the mercy of any chance stimulus or any whim of the moment. He can enjoy nothing. He spends his life searching for some value which he will never find.
PLAYBOY: Couldn't the attempt to rule whim out of life, to act in a totally rational fashion, be viewed as conducive to a juiceless, joyless kind of existence?
RAND: I truly must say that I don't know what you are talking about. Let's define our terms. Reason is man's tool of knowledge, the faculty that enables him to perceive the facts of reality. To act rationally means to act in accordance with the facts of reality. Emotions are not tools of cognition. What you feel tells you nothing about the facts; it merely tells you something about your estimate of the facts. Emotions are the result of your value judgments; they are caused by your basic premises, which you may hold consciously or subconsciously, which may be right or wrong. A whim is an emotion whose cause you neither know nor care to discover. Now what does it mean, to act on whim? It means that a man acts like a zombi, without any knowledge of what he deals with, what he wants to accomplish, or what motivates him. It means that a man acts in a state of temporary insanity. Is this what you call juicy or colorful? I think the only juice that can come out of such a situation is blood. To act against the facts of reality can result only in destruction.
PLAYBOY: Should one ignore emotions altogether, rule them out of one's life entirely?
RAND: Of course not. One should merely keep them in their place. An emotion is an automatic response, an automatic effect of man's value premises. An effect, not a cause. There is no necessary clash, no dichotomy between man's reason and his emotions -- provided he observes their proper relationship. A rational man knows -- or makes it a point to discover -- the source of his emotions, the basic premises from which they come; if his premises are wrong, he corrects them. He never acts on emotions for which he cannot account, the meaning of which he does not understand. In appraising a situation, he knows why he reacts as he does and whether he is right. He has no inner conflicts, his mind and his emotions are integrated, his consciousness is in perfect harmony. His emotions are not his enemies, they are his means of enjoying life. But they are not his guide; the guide is his mind. This relationship cannot be reversed, however. If a man takes his emotions as the cause and his mind as their passive effect, if he is guided by his emotions and uses his mind only to rationalize or justify them somehow -- then he is acting immorally, he is condemning himself to misery, failure, defeat, and he will achieve nothing but destruction -- his own and that of others.