Think of all the criminals who have killed, all the soldiers who have killed consider the mass murder of Jews in Nazi Germany. Is there something inside human beings that allows us to take part in this sort of violence, or were these people swept along by the situation? Stanley Milgram, a New York psychologist, designed an experiment to find answers to this question, paying adult males four and a half dollars to act the role of 'teacher' in a complicated experiment. The 'teachers' were to ask questions of a 'learner', a middle-aged man in another room. If the learner gave an incorrect answer, the teacher was instructed to turn a knob to send an electric current to the learner's chair. There were thirty positions on the control knob, with the shocks ranging from 15 to 450 volts, the last position marked 'Danger: Severe Shock'. The teachers were told to increase the severity of the shock with each incorrect response. With the first few shocks, the learner could be heard over the intercom, grunting and moaning. When the dial reached 150, he demanded that the experiment be ended shortly afterwards, at 180 volts, he began to complain of the pain. At 300 volts, he complained about his heart condition, screamed, and no longer responded to the questions but the teachers who complanined about their roles in the experiment were told the experiment had to continue. According to the rules, the learner's failure to respond was an 'error', so he must be shocked. A group of psychiatrists was asked for predictions. Certainly, they said, most people would not punish the victim beyond 150 volts. Furthermore, they predicted fewer than four percent would persist up to 300 volts only abnormal individuals--less than one tenth of a percent--would proceed to 450 volts. And, in fact, nearly every 'teacher' did protest--each became concerned that he might injure the learner, and many said they could not continue to follow instructions. At 180 volts, one 'teacher' said, 'He's hollering. He can't stand it what if anything happens to him? I mean who is going to take responsibility if anything happens to that gentleman?' When the experimenter said he would accept responsibility, the teacher meekly responded, 'All right.' Some teachers, alarmed by the silence in the next room, called out to the learner to answer so they wouldn't have to continue shocking him. In fact, most of the teachers protested, but the important thing is that they did not disobey their instruction. Sixty-two percent of all the subjects delivered shocks all the way up to 450 volts--the average highest shock was 370 volts. Of course, the learner was not being shocked. Even his screams were tape-recorded. But this experiment and similar variations of it have been repeated several times, and the results are invariably the same: in the presence of authority, in a situation governed by rules. Personality tests given to the subjects who delivered the shocks of 450 volts show that they are not abnormal or sick in any way. They're exactly like the rest of us. The main purpose of this passage is to ______.