Ever since the first Jew arrived on American shores 350 years ago, one question has persistently been asked but never definitively answered. Should Jews accommodate themselves to the culture of the United States, even if so doing carries the risk of serious, sometimes fatal revisions to the traditions that have long defined Judaism? Or should preservation of the traditions come first, even if that means never really fitting into American culture as other groups, primarily Christian, have done?

In recent times, from roughly the 1940s to the 1970s, the predominant response among American Jews was assimilation and cultural adaptation. For many that process continues unabatedindeed, to the point of intermarriage, conversion to Buddhism, adherence to nonbelief, or any one of the myriad ways in which Jewish identity has come to be an ethnic marker, at best, and a label to be avoided, at worst.

But there has also taken place in recent years a searching inquiry about the costs of assimilation. By no means confined to the ultra-Orthodox, some American Jews have wondered out loud what it means to be Jewish unless one takes one's obligations to the traditions seriously. Among those for whom Jewish identity is first and foremost, there exists a palpable sense that American culture is, on the one hand, too seductive and, on the other, too frivolous. People of this persuasion are inclined to believe that earlier generations of assimilated Jews were too willing to leave their heritage behind and too sanguine about what modern, secular, liberal, and, above all else, assimilationist America offered.

While insisting that Jews as individuals offer an American success story, for example, the law professor Alan M. Dershowitz argued as the last century came to a close, in The Vanishing American Jew: In Search of Jewish Identity for the Next Century (Little, Brown, 1997), that "American Jews -- as a people -- have never been in greater danger of disappearing through assimilation, intermarriage, and low birthrates." The distinguished group of scholars who contributed to Manfred Gerstenfeld's American Jewry's Challenge: Addressing the Twenty-First Century (Rowman & Littlefield, 2004) also say that Jews face a set of new problems -- including increasing anti-Semitism, hostility toward Israel on the campuses, and secularization among younger Jews -- that make older models of assimilation problematic. Suggestions about what to do about all that differ according to the suggester: Focus more of Jewish philanthropic efforts on Jewish-community building, turn more attention to efforts to halt intermarriage, put resources into defending Israel, and so on.

As much as I appreciate that effort to insist on Jewish identity, I want to make a case for all the things that American culture would lose if American Jews were to turn their backs on it. Jews made so many contributions to American culture during their "Golden Age" of assimilation that it is difficult to imagine what American life would have been without them. Those contributions, furthermore, raise the question of what kind of culture the United States would have if American Jews turn increasingly inward in the future. Four cultural contributions stand out.

The first was in the arts, especially in the musical theater. It remains a fact of still surprising significance that Jews played a role in celebrating the statehood of a frontier territory like Oklahoma: As Andrea Most points out in her lively history of the Jewish contribution to musicals, Making Americans: Jews and the Broadway Musical (Harvard University Press, 2004), Richard Rodgers and Oscar Hammerstein drew on the themes of Jewish exile to depict the evolution of American culture in Oklahoma! According to Most, the message they conveyed was: "Cowboys must settle down and become farmers; the frontier must be 'tamed' into a useful agricultural resource; young people must marry and bring up new Americans."

Together with others like Irving Berlin and George and Ira Gershwin, Rodgers and Hammerstein transformed the American musical from dancing chorus lines to something resembling European opera. Still, one wonders how many Americans who woke up to a beautiful morning understood that their entertainment was being created by people who, not that long before in America's past, would have been viewed as suspicious because of the mere fact that they were not Christian.

In her book, Most calls attention to the political liberalism that shaped the themes of so much of Broadway musical comedy, culminating in the sermon against racial discrimination put to unforgettable melody in South Pacific. By the time Jews began to arrive in the United States in significant numbers in the early 20th century, they had already established an affinity with political liberalism in Europe. In the United States, the fit was even more perfect. Was it because the United States took such a significant shift to the left during the Great Depression and the New Deal that Jews began to feature so prominently in the liberal life of the nation? Or was it because Jews featured so prominently in the liberal life of the nation that the country shifted to the left?

In either case, a second way Jews had an impact on America was by exercising influence in the Democratic Party, as well as in the interest groups and ideological configurations closely associated with it. Early in the 20th century, Louis Brandeis weaned America from its faith in laissez-faire with legal briefs documenting the actual conditions workers faced on the job. By mid-century, Jews had become prominent actors in the struggle for civil rights. And during the 1960s and 1970s, Jewish organizations like the Anti-Defamation League played a role in protecting the First Amendment's commitment to separation of church and state. Identifying so closely with liberal causes, Jews became, along with African-Americans, the most reliable Democratic voters in America. Ultimately, for the first time in American history, a Jew, Joseph Lieberman, became the party's candidate for vice president in 2000.

A third distinctive contribution made by Jews to American culture was psychoanalysis, which in many ways was linked to Jewish liberalism just as Jewish liberalism was linked to Broadway theater. Psychoanalysis, as Eli Zaretsky has written in Secrets of the Soul: A Social and Cultural History of Psychoanalysis (Knopf, 2004), contains both an element of social control and an element of liberation, but it was primarily the latter strain that influenced American culture in the 1950s and 1960s. Through the work of thinkers like Herbert Marcuse, Lionel Trilling, and Philip Rieff, the ideas of Sigmund Freud permeated the very fabric of American popular and academic culture. Large numbers of Americans began to find in Freud what they increasingly failed to discover in Marx: a way to transform oppressive institutions and practices into an expansion of the sense of personal fulfillment.

Without the arrival of psychoanalysis on these shores, it is hard to imagine how the popular-front politics of the 1930s could have been turned into the identity politics of the 1990s. Each new group that found itself victimized -- women and homosexuals most significant among them -- looked to the Freudian tradition for explanations of the problem that, as Betty Friedan famously put it, had no name. (Although Friedan herself, I hasten to point out, dismissed Freud as hopelessly biased against women.)

All of these contributions made by Jews to American culture were accompanied by a fourth overlapping trend: the transformation of American academic life. Whether you admire his policies or consider him a dangerous threat to the republic, you have to recognize, as he himself does, that George W. Bush might not have gotten into Yale if he had been born a few years later. To their eternal credit, beginning in the 1960s academic leaders like Yale's president, Kingman Brewster Jr., understood that their institutions could not continue to be great universities unless they looked beyond a small number of WASPy prep schools and began to admit students based on merit.

Jews would not only be admitted to universities that had once excluded them; they would also, by the fact of their admission, make the academic research university into a new kind of institution. Peer review, strict standards for tenure, highly selective admissions processes, financial aid based on need -- all those facts of the sociological life in the modern research university follow from the decision to use achievement, rather than background, as the basis for the distribution of academic rewards. When research universities came under attack in the 1960s by radical students, many of whom were Jewish, those who rose to defend the university -- Nathan Glazer, Seymour Martin Lipset, and Daniel Bell, among others -- were also Jewish.

A t the present moment all four of those cultural venues, which once seemed to reflect the Jewish contribution to American culture, are in either serious decline or in the process of transforming themselves into something radically different from what they were during the decades from the 1940s to the 1970s. Let me proceed in reverse order.

The effort to establish merit as the main operating principle by which American academic life would be governed lasted about one generation. Ascription has once again become an important element in the way universities understand their mission, even if the ascribed circumstances that give preference these days tend to be those marked by experiences of racial discrimination and poverty more than by breeding and class. There are many sides to the affirmative-action issues -- and Jews have been predominantly featured on all of them. But there is also a way in which the decision by elite universities to open themselves up to underrepresented groups is perceived by many Jews as an effort to establish quotas, raising the question of whether the kind of university they had come to love still exists.

Freud could never have known that pharmacology would be able to perform, at lower cost and with more rapid results, what his method promised, but once it did, psychoanalysis lost much of the mystique that had made it so popular in the post-World War II era. Not only did Freudian methods lose scientific credibility, but they also lost their cultural cachet. To be sure, thinkers like Jacques Lacan continued to inspire theorists in both Europe and the United States, but the great moments of Freudian literary criticism and historical speculation had come to an end. One of the most popular kinds of therapy these days can be found in the self-help books written by Christian evangelicals, not exactly a terrain in which a specifically Jewish contribution can be noted.

Jewish liberalism continues to flourish; not even President Bush's strong support of Ariel Sharon produced a significant shift in the 2004 presidential election. Yet there is no doubt that American politics has turned decidedly more conservative in the years since 1980 -- or that Jewish intellectuals of a neoconservative bent have played a major role in that change.

There are many explanations for the rise of neoconservatism. Race was clearly a factor; important Jewish intellectuals, including the future best-selling author Allan Bloom, left Cornell University in the early 1970s, for example, in dismay over what, in their view, was the president's failure to confront armed black students. And no one can doubt the importance of foreign-policy considerations to the rise of neoconservatism, especially as the Middle East has assumed such importance for American national security. Still, it would have been difficult to predict that the near axiomatic association between liberalism and America identified by Louis Hartz and Trilling would be broken -- or that Jews would play such a prominent role in breaking it.

The Jewish contribution to the Broadway stage is an exception to many of the trends I have been describing here; it has lasted well beyond South Pacific, culminating in the astonishing work of Leonard Bernstein, Stephen Sondheim, and, most recently, Tony Kushner. Still, as vibrant as the works of those musical and artistic geniuses are, Broadway theater itself is increasingly running revivals of the successful musicals of the Jewish golden age, including Oklahoma! Broadway today is having a difficult time finding what Jewish composers and lyricists of yesterday mastered: music that is neither highbrow and inaccessible nor lowbrow and unfulfilling.

I do not claim to be making a causal argument here, to the effect that an increasing tendency among Jews to withdraw from mainstream American culture in favor of Jewish identity is responsible for the artistic collapse of Broadway, the accession to power of Tom DeLay and J. Dennis Hastert, Freudianism's collapse of credibility, and the turn to affirmative action. Some areas of American life in which Jews once played a major role -- the kind of comedy that produced Sid Caesar and Mel Brooks, for example -- are even more alive now than a few decades past, as the success of a Jerry Seinfeld or a Joan Rivers testifies. No one could seriously claim, moreover, that Jewish contributions to literature are poorer because writers like Allegra Goodman and Nathan Englander pursue specifically Jewish themes.

Each of the developments I have traced has independent causes: Pharmacology did more to harm psychoanalysis than any cultural transformations, for example, and neoconservatism became more attractive because liberals, Jews and non-Jews alike, really did become elitist in the way they treated issues like crime, race, and poverty.

Still, the decline of so many cultural arenas in which Jews once played such a crucial role is more than coincidental. Jews from Central Europe brought the United States forms of high culture -- philosophy, classical music and opera, literary modernism -- that, when blended with American concerns, produced something entirely new. Who today could envision a philosopher of Hannah Arendt's accomplishments writing for what was a quintessential WASP magazineThe New Yorkeror a character like the late Saul Bellow's Herzog writing letters to Arendt's teacher, Martin Heidegger? Jews from Eastern Europe gave us movie classics like Casablanca, an all-American love story taking place in one foreign country occupied by another one. That kind of blending would be threatened if Jews become so focused on their own identity that they lose a zest for blending with the non-Jewish culture around them.

Each of the facets of American culture upon which I have focused was to one degree or another marginal to American life before massive Jewish immigration in the 20th century. We were generally an anti-intellectual culture that looked to Europe for the idea of the research university; our political system was more likely to have been dominated by Harding-Coolidge-Hoover conservatives than FDR or JFK liberals; psychoanalysis was too foreign to be viewed as attractive to Americans; and our styles of popular theater lacked musical and lyrical sophistication. Jews transformed themselves by adapting to American culture so enthusiastically, but they also helped transform America. There really was a golden age of American culture, and it was a direct product of the blending of immigrant experience with classic American themes.

New ways will be found to revitalize American culture as new immigrants arrive; we are already witnessing an extraordinary flourishing of literature produced by Indian and Asian writers, a blending of Latino and American culture in popular music, and fascinating examples of religious syncretism. There are many golden ages, and a new one is growing out of the multicultural energies unleashed in the wake of the immigration reforms of 1965.

Still, there is something to be said for the particular kind of contribution that earlier generations of Jews brought here. Shaped by Enlightenment ideals, it was liberal in the best sense of the term. One need not subscribe to Freud's ideas to recognize the importance of helping individuals to shape lives under their own control. It gave a whole new meaning to middlebrow art. It helped make American universities the model for the rest of the world to follow. It would be a great shame if such cultural contributions were lost.

No matter how important it may be for Jews to focus on their own identity so that their Judaism does not disappear, I hope they do not do so in ways that would further undermine the survival of a form of American culture that speaks to the mind and the heart the way the culture of the great Jewish-American synthesis did over the past half-century.

Alan Wolfe is director of the Boisi Center for Religion and American Public Life and professor of political science at Boston College. His most recent book is Return to Greatness: How America Lost Its Sense of Purpose and What It Needs to Do to Recover It (Princeton University Press, 2005).