There is a utility to stereotyping. The American ethic, not to mention the law, insists that we all be judged as individuals, but the city dweller especially knows better. Having been asked for $5 by four black youths shod for crime in high-top sneakers, Bernhard Goetz saw the stereotype and assumed he was about to be robbed. Many New Yorkers have applauded his rationality.

Consider: who commits an inordinate amount of crime? A small percentage of young black males.

Consider further: Although Goetz could not have known it at the time, all four of the youths who approached him for money had criminal records. At the moment, two are in jail and one is in a drug rehabilitation center. The fourth youth, Darrell Cabey, lives at home, paralyzed from the waist down by the bullet Goetz fired into him.

And one further thing: the request for money is a preface to robbery. It is really a demand, a strange street ritual in which everyone understands that there is no question mark at the end of the sentence. This is the code of New York, if not other places, and everyone in Goetz's subway car knew it.

But in Goetz's case, rational deductions were made by an irrational man. In the first place, he was illegally carrying a gun. Second, he machoed his way into the midst of the four youths while others in the subway car wisely kept their distance. His behavior was the urban equivalent of "smile when you say that, stranger" -- the prologue to so many fights in so many movie westerns: almost a challenge in itself.

When it was accepted, Goetz responded not simply by showing his gun (the four youths were unarmed), but by opening fire. He blazed away, and later, in a taped confession, he repeatedly mentioned that he had once been a mugging victim. His actions and his words were of a man who thought he had finally settled a score.

The dilemma of the Goetz case lies in the difficulty of distinguishing between a rational fear based on a stereotype and the irrational behavior that can result. Life is too complicated, the city too menacing, to judge every person as an individual. A person of whatever race -- black or white -- is entitled to extrapolate on the basis of either experience or knowledge (crime statistics) to make certain judgments. Only a fool would treat Goetz's four boisterous black youths apparently looking for trouble as if they were four Iowa farm kids out to see the Big City.

Prudent, self-defensive behavior is not the same as aggressive, retributive action. What Goetz did was the moral equivalent of a white mob running through a black neighborhood, beating and, maybe, lynching the first person it encounters because a wholly different black had injured or killed a white. The fury of Goetz's attack was fueled not only by the demand for money, but by his previous mugging.

Race, but not necessarily conventional prejudice, undoubtedly played a role. The fear here is specific, not general -- not an entire race, but just the young, male members of it who dress and act in a certain menacing way.

That always-moving, always-thin, line between rational fear and irrational action is one of civilization's essential threads. Pull it, and society begins to unravel. The fears of the urban American are real -- as is the threat to him or, more likely, her. Crime and the threat of it have atomized our already weakened communities. People live in virtual vaults behind door locks and window bars. They will not walk their own streets at night, or, in some places, during the day. The old are tremulous, often victimized by the young. Cabs will not stop for certain people, and, for many, dogs are no longer pets, but weapons of self-defense.

But the law rightly insists that our actions be reasonable. It does not require you to be unafraid, not to dart or sneak out of harm's way or not to suspect the stranger. But it does uphold the worthy standard that you have no right to translate your fear into aggressive, dangerous action that is out of proportion to any threat. Bernhard Goetz did that.

He was right to suspect those four youths and even right to fear them. But when -- one by one -- he shot them, he committed a crime and so, in acquitting him, did his jury. It moved the line between rational fear and irrational action a little closer to the jungle