The skyjackers at Entebbe. The killings at the 1974 Munich Olympics. Uruguayan Tupamaros kidnaping and killing an American public safety adviser. The public reels in shock and horror at these and other terrorist activities, but Dr. Frederick J. Hacker studies them.

Hacker, a psychiatrist and the author of a new book, "Crusaders, Criminals and Crazies: Terror and Terrorism in Our Time," which he is promoting, wants to do for aggression and terror what Sigmund Freud did for sex: show us how these elements pervade our "normal" behavior and how the guardians of society often respond with the same terror tactics as the people they seek to control.

"I've never trusted overt and apparent peace," explains the grandfatherly, 62-year-old Hacker of his interest in terrorism. "I grew up in Vienna in a very bourgeois family, with a very sheltered life. My background is Jewish - but we never practiced the faith, questioned who we were. Then the Nazis came in and my whole life was turned upside down. It was a surprise. We hadn't done anything wrong, yet here we were being labeled and killed for an accident of birth."

Since then Hacker has "become very familiar with disaster lurking around the next corner" and the power of defining abberant behavior. Hacker's weltanshauung of terror has made him an authority on the subject. He was the court-appointed expert at the Charles Manson trial, worked with the Hearst family immediately after Patty Hearst's kidnapping, and was consultant to the West German government during the Munich Olympic tragedy.

Though terror and its use to control others is nothing new, what compels Hacker is the democratization of terror tactics.

"The molotov cocktail is a much more decisive invention than the atomic bomb," Hacker says, arguing that every group or cause now has the means and opportunity - through media exposure - of terrorizing larger numbers of people into responding to them.

At the same time, Hacker says, people are being desensitized to escalating tactics of terror of controlling terrorists, an acceptance that can easily be used to manipulate them.

Violent responses from the police or other authorities to terrorist Hacker finds "most dangerous because the actions are considered normal. I'm trying to protect human freedom from manipulation, to make people aware of how relative their viewpoint is. The terrorist doesn't think he's a terrorist and in dealing with them we have to remember that they think they're as right as we do."

Hacker, who is chief of staff at the Hacker Clinics in Beverly Hills and Lynwood, Calif., is also president of the Sigmund Freud Society in Vienna. It was at the opening of the society that Hacker's interest in modern terrorism began to develop.

"Here we were, a gathering of psychiatrists from all over the world, and naturally there were a lot of papers read," he recalls. "But very few papers dealt with what you could read about in your daily newspaper. The papers weren't dealing with this contemporary phenomenon of terrorism on a new scale."

Hacker, a bachelor, finds his life suffused with the study of terrorism and aggression. "I commute between Europe (where he is director of the Institute for Conflict Research in Vienna) and California like some people commute to Glenwood (Calif.) I live an eliptical existence."