Washington ? Peter Beinart is an advocate of liberal – not “progressive” – nostalgia. He wants to turn the clock back to 1947 at Washington’s Willard Hotel.

Beinart, who was born in 1971, is editor at large of the liberal New Republic magazine and disdains the label “progressive” as a rejection of liberalism’s useable past of anti-totalitarianism. An intellectual archaeologist, he excavates that vanished intellectual tradition and sends it into battle in his new book, “The Good Fight: Why Liberals – and Only Liberals – Can Win the War on Terror and Make America Great Again.” It expresses Beinart’s understanding of liberalism in 1948, 1968 and, he hopes, 2008.

His project of curing liberalism’s amnesia begins by revisiting Jan. 4, 1947, when liberal anti-totalitarians convened at the Willard to found Americans for Democratic Action. It became their instrument for rescuing the Democratic Party from Henry Wallace and his fellow-traveling followers who, locating the cause of the Cold War in American faults, were precursors of Michael Moore and his ilk among today’s “progressives.”

Among the heroes of liberalism’s civil war of 60 years ago was Arthur Schlesinger Jr., who today is 88. He stigmatized their anti-anti-communism as “doughface-ism.” Beinart explains: “The original doughfaces were ‘Northern men with Southern principles’ – Northerners who opposed slavery, but who could not bring themselves to support the Civil War.” Today’s doughfaces are “progressives” who flinch from the fact that, as Beinart says, “America could not have built schools for Afghan girls had it not bombed the Taliban first.”

Liberalism’s civil war seemed won after Henry Wallace’s Progressive Party candidacy failed to prevent President Truman’s 1948 election. But the war broke out again in the Democratic Party’s crack-up over Vietnam in 1968. Then, Beinart says, a “new liberalism” emerged that “questioned whether America had much to offer the world.” Four years later the party nominated George McGovern, who had been a delegate to the 1948 Progressive Party convention that nominated Wallace. McGovern’s trumpet sounded retreat: “Come home, America.”

Since then, Beinart argues, liberals have lacked a narrative of national greatness that links America’s missions at home and abroad. It has been said that whereas the right-wing isolationists in the 1930s believed that America was too good for the world, left-wing isolationists in the 1960s believed that the world was too good for America. After Vietnam, Beinart says, liberal foreign policy was “defined more by fear of American imperialism than fear of totalitarianism.”

Beinart briskly says “I was wrong” in supporting the invasion of Iraq. Wrong about Saddam’s nuclear program. Wrong in being “too quick to give up on containment.” Wrong about the administration’s competence to cope with the war’s aftermath. (“Staffers tasked with postwar reconstruction were told to bring two suits. They would be home by the end of summer.”)

Denouncing conservatives for waging a “war of hubris and impatience,” Beinart says “George W. Bush has faithfully carried out the great conservative project. He has stripped away the restraints on American power, in an effort to show the world that we are not weak. And in the process, he has made American power illegitimate, which has made us weak.” Because “the more proactive America wanted to be, the stronger international institutions had to become.”

But while excoriating the Bush administration for perhaps “creating exactly the condition the conservatives have long feared: An America without the will to fight,” Beinart’s most important contribution is to confront the doughface liberals who rejoice about the weakening of that will. Reading liberals who seem to think they “have no enemies more threatening, or more illiberal, than George W. Bush,” Beinart worries that Deaniac liberals are taking over the Democratic Party much as McGovernite liberals did after 1968. He discerns the “patronizing quality” of many liberals’ support for John Kerry in 2004: They “weren’t supporting Kerry because he had served in Vietnam. They were supporting him because they believed other, more hawkish, voters would support him because he had served in Vietnam.”

Beinart worries that “the elections of 2006 and 2008 could resemble the elections of 1974 and 1976, when foreign policy exhaustion and Republican scandal, propelled Democrats to big gains.” If so, those gains will be “a false dawn.” The country will eventually turn right because, “whatever its failings, the right at least knows that America’s enemies need to be fought.”

Ronald Reagan said he did not want to return to the past but to the past’s way of facing the future. As does Beinart, who locates the pertinent past in 1947.