ON ELECTION night last November, I went to a party at a stylish apartment overlooking New York's Central Park. Present were many veterans of the anti-war, civil rights and women's movements who had that day -- with varying degrees of enthusiasm -- voted for Mondale-Ferraro.

By early evening, the portents of a Reagan sweep were in the air. In one corner, I joined a grim seminar grappling with large questions: Was this really the equivalent of 1936, the consolidation of a new majority which would dominate American politics for a generation to come? If so, where had the Roosevelt-Truman-Kennedy-Johnson coalition begun to unravel? And why did so many Americans regard this tradition as sterile and irrelevent?

In this thoughtful book, Jonathan Rieder argues that the answers to some of those questions could have been found scarcely 10 miles away on the shores of Jamaica Bay. There, among shabby brick row houses and flaking bungalows, the lower-middle-class Jews and Italians of Canarsie were receiving Reagan's landslide in a very different mood. In the widening gap between Rockaway Parkway and the Central Park West -- the author suggests -- lies the root of the Democratic Party's current enfeeblement.

Rieder, who teaches sociology at Yale, focused on Canarsie because in the '70s that swatch of southeast Brooklyn erupted in white backlash against school desegregation and other perceived threats to its racial character. After a 1972 boycott kept 10,000 children out of school for more than a week, The New York Times warned, "The shameful situation in Canarsie illustrates the forces of unreason sweeping over the city and nation."

Seeking the meaning of such behavior, Rieder spent 18 months during 1976-77 in Canarsie and has returned intermittently since. He hung out at the Jefferson Democratic Club, ate blintzes with the orthodox Jews in Grabstein's Deli, shopped for mortadella in the groceries along Avenue L, kibitzed over the card games on Canarsie pier. These pages leave little doubt that he came to know the community well and to understand the forces which moved its fearful citizens.

Many Canarsians had already fled twice from black intruders -- first from Brownsville to the northern tip of eastern Flatbush, then south into Canarsie. Now, facing the prospect of Brownsville children being bused into Canarsie schools, they feared that the racial cycle was beginning all over again. One Jewish leader invoked the image of a threatened Israel when he said of his own people's dilemma: "We ran once, but we've nowhere else to go. We're surrounded. The water is at our back."

My own research in Boston's white neighborhood's during this same period convinces me that Rieder is right in placing such racial hostilities in a broader context of social disaffection -- "the precariousness of their (Canarsians') hold on middle-class status, the recency of their arrival in that exalted position, and the intense fear that it might be taken from them." All the institutions which had once offered comfort and consolation -- the church, the press, the courts, the schools -- had seemingly turned against them. They felt betrayed, abandoned, cut off in a hostile world.

AND TO MANY of these second and third-generation Americans, no organization seemed more indifferent to their fate than the party of Franklin Roosevelt, Al Smith and Herbert Lehman to which their parents and grandparents had offered such passionate attachment. The defections began in 1968 when Richard Nixon first started wooing "Middle America"; picked up steam in 1972, when the Democratic challenger personified many of these voters' worst anxieties; were momentarily blunted in 1976 by Watergate and Jimmy Carter's bland appeal; then accelerated once again in 1980 and 1984.

Rieder documents all this with scholarly precision, while generally eschewing the academic jargon which so often makes sociology utterly unreadable. And yet I have one major reservation, which perhaps ought to be addressed less to this author than to the conventions of his discipline.

In obeisance to "the ethical imperatives of confidentiality," He has removed all but a handful of the best-known names in the book. Thus, we get an endless parade of cardboard attributions: "a Jewish housewife," "an Italian dockworker," "a furrier's son." Moreover, Rieder concedes that he has changed "a few details," which might otherwise makes these people identifiable. Thus, we cannot even have confidence in the little information he gives us about them. What is to prevent him from changing "a Jewish insurance salesman" to "a Jewish grocer?" Once this kind of camouflaging begins, it is hard to stop.

Well, some readers may ask, what difference does it make? An insurance salesman probably feels much the same as a grocer anyway. To me it makes a difference. When we are told that "an Italian truck driver" voted for George Wallace, I want to know more about this man. Is he a 34-year old Vietnam veteran for a 64-year old member of the VFW. Does he smoke pot with his teen-age cousins or play bocce with hs dyspeptic neighbors? Is he a high school drop- out who reads Hustler or an opera nut who treasures La Traviata?

Does this kind of research really demand that all the quirky, intriguing things about human beings be washed away in the name of "confidentiality." I think not.

Such doubts notwithstanding, there is much in Canarsie to which we should attend. When Rieder warns in his conclusion that Brooklyn's Jews and Italians "did not simply bolt from the Democratic party, they were driven out of it," when he cautions that "left- liberalism hardened into an orthodoxy of the privileged classes," all of us who were dismayed by Reagan's landslide last November ought to listen carefully.