Only a former speechwriter for President Clinton could write a history as replete as this one with equivocation, empty rhetoric, and triangulation. Ted Widmer’s “Ark of the Liberties” (Hill and Wang, 384 pages, $25) presents itself as a survey of presidential leadership on the subject of freedom at home and abroad, though it’s really not a history at all, but a tawdry score-settling enterprise designed to cast a favorable light on his former boss and previous Democratic presidents, and an unfavorable one on most of the Republicans who have occupied the office.

Talk about chutzpah. How could anyone write a subchapter on the Clinton foreign policy record and not mention Al Qaeda’s first World Trade Center bombing, or the bombings of the USS Cole and American embassies in East Africa? It really carries you back in time to the Clinton White House, where truth and falsehood depended “on what the definition of ‘is’ is.”

Mr. Widmer’s most prominent theme here — American exceptionalism as the beacon of freedom to the world — is classic triangulation. While most liberals have been loath in recent decades to make such moral claims, Mr. Widmer takes a traditionally conservative position and turns it into a cudgel against Presidents Nixon, Reagan, Ford, George H.W. Bush, and, most savagely, George W. Bush. The real Clintonista touch, however, comes in the epilogue, in which the author first asserts that “this is not a book about the Bush administration,” and then lets the daggers fly.

But it is worth pausing for a moment to contemplate how a group of patriotic leaders could have inflicted so much harm, so quickly, on the world order that had been created by their own country. Perhaps there was a structural flaw in our democracy that we were unaware of until now — namely that the ease of entry into American politics, combined with our vast military might, gives just about anyone a chance to rule the world.

This statement is, indeed, worth pondering, not so much for its assessment of the Bush administration as for its underlying contempt for the system and voters enabling the “miscreants.”

Mr. Widmer appears unaware of any progress on the ground in Iraq, however halting, and he takes something of a risk by predicting military failure there. Unlike the Democratic candidate for president, however, he can’t simply revise or eliminate such predictions from his campaign Web site. Books have a different way of keeping score. It’s doubly a pity that Mr. Widmer has taken on this subject because a very fine book could be written on America’s historic role as a promoter of human liberty around the world; this polemic probably crowds out that possibility, at least for now.

In fairness, however, Mr. Widmer’s first chapters, which deal with the Colonial and Revolutionary periods, are fairly straightforward and even illuminating on the widely shared conviction that something new in human history was coming to be on American shores. It’s only really when he gets to the 20th century that the political agenda emerges and we discover how selective he is in recalling presidential performance on the spread of human liberty. Thus, President Wilson’s suppression of dissident opinion during World War I and President Franklin Roosevelt’s internment of Japanese Americans merit only brief mentions. The hanging of pro-German terrorists under Roosevelt gets no mention at all during the lively discussion of Abu Ghraib and Guantanamo. Likewise, President Truman’s imposition of a loyalty oath for federal employees is unacknowledged during a survey of the McCarthy era.

While all this is boilerplate partisanship, the truly vile material in this book concerns the author’s effort to credit Mikhail Gorbachev with ending the Cold War.

Twisting when he is not triangulating, Mr. Widmer takes the notion of moral equivalence between the superpowers and ups the ante by ceding the moral high ground to Mr. Gorbachev, a man who did everything he could, short of war, to preserve the Soviet Union.

This is a shameless book, but it is unlikely to do much damage. Its author is so obviously calculating that he, like his former boss, becomes his own worst enemy.

Mr. Willcox, a former editor in chief of Reader’s Digest, lives in Ridgefield, Conn.