During the 1960s, psychologist Stanley Milgram set out to study how obedient human beings can be to authority. Three months after the start of the trial of Nazi war criminal Adolf Eichmann in Jerusalem, he set up an experiment designed to determine whether ordinary people could be coaxed to inflict suffering on innocent people simply because they were ordered to do so.

In the now-famous Milgram experiment, volunteers were told by an "experimentor" that they were participating in a study about learning. Each individual believed he or she was the "teacher," administering electric shocks to another volunteer in a separate room each time that person failed to answer a question correctly about word pairs. In one version of the study, the "learners" mentioned having heart conditions.

As the learner made more and more mistakes, the shocks were increased. If the teacher hesitated, the experimentor stated that the experiment had to continue.

In fact, only the "teachers" giving the shocks were being studied. The learners were researchers, too. No real electric shocks were being administered, though the learners - who were good actors -screamed as the teachers really dialed up the electricity.

Heart conditions or not, about two-thirds of the study volunteers continued to deliver electric shocks to their students, even when they were told to deliver the maximum 450 volts - enough to cause permanent injury or even death.

Milgram had proven that average individuals presented with rules and an authority figure to enforce them (the experimentor), would hurt other innocent people they had never met.

Now, some 45 years later, psychology professor Jerry Burger at Santa Clara University has confirmed Milgram's findings. In a modified version of the Milgram experiment (with somewhat lower voltages, but plenty of "learner" suffering), volunteers remained willing to torture their students for wrong answers, as long as they were consistently told to do so by an "experimentor." In fact, about 70 percent of the volunteers were willing to keep delivering shocks until the highest voltage level was reached (this time, 150 volts).

The Burger experiment has caused a stir in the psychology research community because of concerns that volunteers were not informed that the experiment was a "sham." Although the Burger team tried to screen out those who might be incapacitated by guilt after participating, or who might become depressed, there's really no way to know if they might be harmed by the experience of "hurting" another person so badly.

That ethical debate is likely to rage on for some time. But the data isn't being challenged_ Most human beings are willing to inflict terrible pain on innocent people they have never met when an authority figure consistently tells them to do so. What does that say about us? What does it predict about the potential for genocides and other calamities in the future?

I believe it tells us one very important thing about our view of decency and morality. Our notion that there are evil people and good people among us is too simplistic. A majority of us can lose our moral bearings and do the bidding of evil by ceding our own personal autonomy to that of someone who instructs us, with authority, to harm our fellow man. This fault line between good and evil cuts through the hearts of the majority of us, not a rare and select group.

This explains much about the behavior of street gangs and terrorist cells and cults and nations with strongmen with their sights set on the destruction of others. When a group - even a whole country - is in the grip of a charismatic leader giving consistent and forceful instructions on what must be done, the population is likely to get in line and do it. It doesn't make every citizen of the nation the devil. It doesn't necessarily mean the country is filled with people who are, at heart, morally different than we are. But it does mean that they can be passive instruments of untold suffering.

In this world, at this time, in our species, the field of psychology tells us it will depend on those with a clear vision and a strong voice and absolute resolve to protect the rights of others and oppose the forces of destructiveness sure to gather in the coming years. Our safety and security and capacity for goodness all require strong leaders to stand firm for the very best in us, and stand even firmer against the worst in any of us.

Dr. Keith Ablow is a psychiatrist and member of the Fox News Medical A-Team.