Richard Hosftadter's classic essay, put online by Prof. Kenneth Rahn of the University of Rhode Island. Especially recommended for our foreign friends, who may be puzzled by this element in our national culture.
Perhaps the central situation conducive to the diffusion of the paranoid tendency is a confrontation of opposed interests which are (or are felt to be) totally irreconcilable, and thus by nature not susceptible to the normal political processes of bargain and compromise. The situation becomes worse when the representatives of a particular social interest --- perhaps because of the very unrealistic and unrealizable nature of its demands --- are shut out of the political process. Having no access to political bargaining or the making of decisions, they find their original conception that the world of power is sinister and malicious fully confirmed. They see only the consequences of power --- and this through distorting lenses --- and have no chance to observe its actual machinery. A distinguished historian has said that one of the most valuable things about history is that it teaches us how things do not happen. It is precisely this kind of awareness that the paranoid fails to develop. He has a special resistance of his own, of course, to developing such awareness, but circumstances often deprive him of exposure to events that might enlighten him --- and in any case he resists enlightenment.We are all sufferers from history, but the paranoid is a double sufferer, since he is afflicted not only by the real world, with the rest of us, but by his fantasies as well.
(Via Dan Drenzer)