We might as well call it: The American left is dead. Faced with the greatest crisis of capitalism in almost a century, the left has mounted no effective mass protests, inspired no significant uprisings, spawned no major institutions or policy revolutions. In Wisconsin, labor unions lost their greatest public battle since Ronald Reagan’s showdown with air traffic controllers. In the midterm elections, the Tea Party, not the left, took advantage of economic discontent to upend the status quo. Today, the dream of socialism exists mostly as a far-right phantom, to be conjured up when Democrats dare to imply that Medicare or Social Security might serve the public good.

The historian Michael Kazin acknowledges that Americans have reached what may be “a nadir of the historical left.” But he urges sympathizers not to despair. According to Kazin, the American left has never been much good at building institutions, or getting people elected or seeing its economic programs realized. But it has been enormously effective at shifting the nation’s moral compass and expanding its sense of political possibility. The real problem for today’s left, Kazin writes, is that its members have forgotten how to think big — how to look beyond the uninspiring present to a more dazzling and egalitarian future. Defending Medicare and Social Security may be all well and good, but what ever happened to utopia?

“American Dreamers” is Kazin’s bid to reclaim the left’s utopian spirit for an age of diminished expectations. An editor at Dissent magazine and one of the left’s most eloquent spokesmen, Kazin presents his book as an unapologetic attempt to give the left a history it can celebrate. For more than two centuries, he writes, American radicals have sounded the alarm about crucial injustices — slavery, industrial exploitation, women’s oppression — that the rest of society refused to see. It is time for the left to stand up and take credit for these efforts.

Who is — or was — “the left”? Today, many Americans use the word interchangeably with “liberal.” As Kazin points out, this would have been anathema to earlier generations, when leftists and liberals often viewed each other as ideological foes. For most of the 20th century, liberalism meant tinkering, finding a kinder and gentler way to preserve the status quo. Leftists, by contrast, put their faith in structural change. Kazin’s left includes all those who fought for a “radically egalitarian transformation of society,” from abolitionists to Communists to the modern feminist and gay rights movements.