In the New Yorker in 1996, Malcolm Gladwell published "The Tipping Point," an article about the surprising drop in New York City’s crime rate. The article attracted a good deal of attention and inspired this book, which he calls "the history of an idea." The idea of the tipping point originated in discussions of racial change in the early 1970s. In schools where the number of black students is increasing slowly and steadily, for example, there may come a point at which the percentage of black students abruptly begins increasing much more rapidly as white students leave. So too in neighborhoods, a slow or moderate increase in the number of black families seems at some point to trigger a much more rapid change. In both cases, the aim of achieving a stable mix of black and white is thwarted. Classrooms and neighborhoods seem to move from segregation to segregation, white to black, with a frustratingly brief period of integration in between. The phenomenon has inspired considerable research, some of it rather naively trying to determine whether some magic percentage triggers the rapid escalation of change.

Gladwell, after briefly describing the origin of the term, does not deal with racial integration. Instead, he tries to use the tipping point to explain a variety of rapid changes. He begins with the case of Hush Puppies, a brand of relatively cheap shoes that were once popular, lost their appeal, then suddenly regained it when they became hip in the clubs and bars of downtown Manhattan. From being found only occasionally in outof-the-way, unfashionable stores, Hush Puppies became widely available big sellers. "How," Gladwell asks, "does a $30 pair of shoes go from a handful of downtown Manhattan hipsters and designers to every mall in America in the space of two years?" He follows this with a second introductory case, that of the decline of crime in a New York City neighborhood.

What links these two cases, according to the author, is the tipping point, a concept he finds best formulated in epidemiology. Can the Hush Puppies fad and the New York City crime drop be explained in the same way as the spread of flu in a community? That is Gladwell’s claim, and he leads us through an entertaining collection of stories and studies in developing it. Many of his encounters are with social scientists who study such matters as the spread of rumors. Some are with people who help popularize new ideas, whom he calls Connectors, Mavens, and Salesmen. They are people who know a lot of people, or who are interested in knowing about new things, or who speak with confidence and credibility. Not many of them are necessary to start a trend. All this is very much in the New Yorker vein—we meet interesting people who seem much better connected than you or I, and who may well be able to start fads.

But is this to be explained by the tipping point, however we interpret it? When we speak of a tipping point in the effort to achieve stable racial integration, our problem is bounded. Difficult as it is to find the percentage that uniformly triggers the rapid escalation of change, we know what we are talking about. We know too the various motives and influences that drive the change: People are afraid that the quality of education will decline, or that their children will feel endangered, or that the value of their property will drop. But when it comes to Hush Puppies—or, to take another case about which we are told a great deal in this book, the children’s TV programs Sesame Street and Blue’s Clues—we seem to be talking of a much more familiar and widespread phenomenon: magazines, programs, books, fashions that start small and take off. Is it the case that when a TV program reaches only x number of viewers it will struggle and possibly fail, but when it reaches x plus y it will soar? In that event, something like a tipping point would be operating, but that is not what Gladwell describes in most of his cases.

Some of his notions work well enough for selling and merchandising but seem ill suited to large social issues. Consider the crime drop. In what sense is this a consequence of Connectors, Mavens, and Salesmen? To what extent does his "Law of the Few"—it takes only a few people to set an innovation going—apply? In the Hush Puppies case, these figures spread the idea through example by wearing the shoes. What is the equivalent in the case of the crime drop? Yes, approaches to policing have played a dominant role in the crime drop (though some think the huge increase in incarceration and the prosperity of the past half-dozen years have played as large a role). Those who advocated these approaches—including criminal justice scholars George L. Kelling and James Q. Wilson with their "broken windows" thesis, and then-chief of police William Bratton with his computerized crime statistics to guide police deployment in Boston and New York—played key roles. But they were advocating ideas and procedures to deal with a serious social problem. That is different from selling Hush Puppies—so different I fail to see the connection.

It is also hard to see how the principles of epidemiology apply to the crime rate. The curve of rising or falling crime may resemble the curve of a spreading or controlled disease, but all kinds of unrelated phenomena surprise us with similar curves. The explanations are radically different. A disease may be checked by an antidote, or it may exhaust itself by reaching all those susceptible, or immunity may spread in the population, or a quarantine may work. The crime rate falls because of surrounding social conditions, or because the supply of criminals has been reduced by imprisonment, or because penalties have become more certain or harsher and dissuade persons from criminal acts, or because policing has become more effective. If we are concerned about checking crime, we must attend to these factors rather than the similarity of curves of incidence.

After his entertaining and in part enlightening and educational foray through all kinds of phenomena, one wonders what Gladwell has added to the idea of the tipping point in its original realm, race. What do Connectors, Mavens, and Salesmen have to do with transformations in the racial composition of schools and neighborhoods? Very little. What is crucial in these cases is individual and family self-interest, whether well or badly understood, drawing on key motives that influence our actions. Whites may not be threatened by a few blacks, or blacks of the same income and class—though that, too, will vary, and a single black homeowner in a neighborhood may trigger very unpleasant reactions. Misguided policy may contribute too. In a nation where 20 percent of the population moves every year, it does not take long for a school or a neighborhood to be transformed. How these transformations occur is a complicated story, and I don’t see how Gladwell’s concept of the tipping point helps us deal with it.

> Nathan Glazer is professor emeritus of sociology at Harvard University. His books include Beyond the Melting Pot (with Daniel Patrick Moynihan) (1963), The Limits of Social Policy (1988), and We Are All Multiculturalists Now (1997).