American Dreamers: How the Left Changed a Nation by Michael Kazin Knopf, 329 pp., $27.95

Michael Kazin’s new book about American leftists and their impact on the nation over the last two centuries presupposes, as its subtitle suggests, that this impact has been enormous. But Kazin is a judicious scholar without bluster, a professor of history at Georgetown, and coeditor of Dissent, and his assessments are carefully measured. Kazin concedes that radical leftists have often been out of touch with prevailing values, including those of the people they wish to liberate. He concludes that American radicals have done more to change what he calls the nation’s “moral culture” than to change its politics.

And yet, even as Kazin tries to avoid romanticizing the left, his book leaves unchallenged some conventional leftist conceptions about American politics and how change happens. These conventions begin with a presumption about who controls American political life, what C. Wright Mills called the “power elite,” an interlocking directorate of wealth and bureaucracy at the top. Kazin refers to this directorate interchangeably as the “establishment” or the “governing elite.” Unless challenged by radicals, this elite, in his view, is slow to right social wrongs; but without the support of the elite’s more enlightened elements, the radicals remain in the political wilderness.

Occasionally—as with the abolition of slavery, the rise of the New Deal, and the victories of the civil rights movement—momentous changes supported by radicals have indeed come to pass. Yet Kazin argues that the liberal components of the governing elite have supported major reforms strictly in order to advance purposes of their own. Abraham Lincoln and the Republicans, he writes, embraced emancipation only halfway through the Civil War, when it became clear that doing so “could speed victory for the North” and save the Union, their true goal. Franklin D. Roosevelt endorsed labor’s rights only when he needed to court labor’s votes.

Even when they are successful, Kazin writes, the radicals—“decidedly junior partners in a coalition driven by establishment reformers”—end up shoved aside as the liberals enact their more limited programs and take all of the credit. Prophets without honor, the leftists return to the margins where they and later radicals dream new and bigger dreams until another social movement jars the establishment.

Some radical historians—most famously the late Howard Zinn—have described this pattern as a chronicle of thoroughgoing oppression. In their view, the reforms initiated by radicals have practically always turned into swindles, orchestrated by clever rulers to preserve and even reinforce their power. Kazin, who…