By now, there's nobody left in the world who needs convincing that America is a violent society. Handgun sales alone announce the obvious. Children patrol their neighborhoods, armed with baseball bats. Young men with wild ideas stalk the rich and celebrated. Peddlers of door locks and guard dogs are doing a booming business, and the evening stroll has become a subject for nostalgia.

"So, that's capitalism," say the Russians. "Cowboy mentality," sniff the Israelis. "A sick society," agree the media. But they're wrong, all wrong. America is not becoming more violent. It is, in fact, becoming less inclined to tolerate violence in all its forms than ever before.

This is not an exercise in double-think. Despite our shorter emotional fuses, our heightened sense of fear and outrage, our despair in human nature, we have undergone a fundamental change in attitude toward violence since World War II. This struck me while I was listening to a recording of a Canadian flying ace telling a home-town audience how he decapitated a German with a burst of bullets. The audience was laughing. "It's really gratifying to be able to blow your enemy's head off," says the hero. There are cheers and applause from the assembled druggists and dry goods merchants, church ladies and children. Nobody vomits. Nobody walks out in protest. Nobody writes an editorial deploring the acceptance of horror.

Nowadays, soldiers with similar memories recount them only in group therapy, or to themselves, in nightmares. Unlike the heroes of the last "great" war, Vietnam veterans are not popular after-dinner speakers. We feel a little uncomfortable about this, as we did not intend to leave a generation of anguished young men alone with their guilt. But we can't bring ourselves to applaud, for we've found that we no longer admire bloodshed in any cause; we are unable to gloat over a kill. This is not merely an aberration of this particular war. Unfortunately for the fighting men and women of the future who will have to live with flashbacks of exploding friends and mangled babies, it is a characteristic of war from now on. Before Vietnam, it was possible to suspend the Golden Rule and find glory in bloody murder because of our strong human tendency to follow the flag and keep the faith, to group people according to several common characteristics and then despise them for being different. But something unsettling has happened to us recently; boundaries between us and them have become blurred, and who is right is no longer clear.

Over the past 35 years, lines separating race, class, religion and nation have been crossed and re-crossed until even the strangest people seem familiar. A generation ago, anthropology was an infant science; today the private lives of the most primitive people on earth are detailed in the morning paper and beamed into our living rooms at night. Eighty thousand returned Peace Corps volunteers remember friends left behind in mud huts on the other side of the world. Millions of schoolchildren have been bused back and forth over ghetto barriers, wearing the barriers away like water flowing over stone. Thousands of the middle class have trekked into the slums to see what could be done, and after surveying the chaos in the lives of four-year-olds, are not so quick to condemn them when they pick up guns at 14. Not so long ago, the mentally retarded were thought "crazy" and uneducable, and children used to run, shrieking, from victims of cerebral palsy. Now, Down's syndrome children teach gymnastics on television, and machines translate the humorous remarks of the handicapped onto paper tape, forcing us to disregard outward appearances and concentrate on human similarities.

Even the barriers that keep us apart from other animals are crumbling as we record the soliloquies of whales to play back to ourselves on sleepless nights, and teach chimpanzees and gorillas the language of the deaf. City people, no longer accustomed to the casual slaughter of farm animals, have taken on a sensitivity that would have been laughable 35 years ago. Families find togetherness in vegetarianism. They fight for the lives of baby seals, organize weekend excursions to commune with a whale, and howl in protest when biologists suggest sending coyotes to control the deer population on an overgrazed island.

Television, meanwhile, has brought black families into the homes of every white bigot, semi-bigot and liberal with reservations in the nation. Suddenly people who once all looked alike, acted alike and dreamed alike, so far as most whites were concerned, took on personality traits that everyone recognized, and blacks turned out to be funny, warm, arrogant, outspoken, thick-headed and totally impossible-- just like our own relatives. Gallup polls over 21 years record the result: progressively pro-black attitudes on the part of whites. Eighty-one percent would have voted for a "well-qualified" black president in 1978, while only 42 percent would have done so in 1958.

Once we see people as family, we can no longer fear them, or push them aside. We're forced to care about them as we would our own relatives, however illogical or imprudent it may be. We should never have gotten to know the American hostages in Iran; it put us in a pathetically weak position. We should have seen them, as we would have, 35 years ago, as regrettable pawns of war and been willing to sacrifice them to eliminate terrorism, once and for all. But who didn't imagine them as their own brothers, sons and sisters? The media made them our family, and we embarrassed them with family sentiment when they came home, almost against our will. Technology has accomplished what generations of preachers were unable to do: brotherhood is no longer a sweet Sunday feeling but a permanent part of our collective personality.

When everybody is family, it becomes possible to care about the least member. In what less violent moment in history would an entire nation be horrified at the deaths of a few dozen of its poorest and most outcast children? In what century would millions be engaged in impassioned debate over whether or not stopping the growth of a microscopic collection of human cells constitutes murder? In what former society would intellectuals crusade for the preservation of iguanas and carp, and endure months of isolation and discomfort to convince a few chimpanzees to return to the wild?

It's not that human nature has changed. The roots of compassion, altruism and peaceful exchange extend back to our primate ancestors. But as technology advances, it not only makes murder and terrorism easier, but breaks down the fierce tribal loyalties that make them seem necessary.

At the very moment that it has become possible for everyone to blow each other away with millions of mass-produced handguns, it has also become possible, for the first time, to feel everyone's suffering as our own. The birth pangs of brotherhood are shockingly painful, but as we've always known, enduring them is the only way we'll survive.