"Example is the school of mankind," proclaimed Edmund Burke, the founder of modern conservatism, "and they will learn at no other."
Burke was disparaging the folly of French revolutionaries who believed that man could break the iron chains of history and create utopias through willpower and planning.
This argument about whether history has anything to teach us has been the essence of the left-right debate for most of the last two centuries. Conservatives said: "There's nothing new under the sun." The left said: "Until now!"
Karl Marx - with a lot of dialectical mumbo jumbo - was the most famous champion of the need to change history, not interpret it. But my favorite summary of this mind-set comes from Stuart Chase, the intellectual often credited with coining the phrase "New Deal" for FDR. "Are our plans wrong?" he asked. "Who knows? Can we tell from reading history? Hardly."
Now, this right-left divide is falling apart, as both sides search for a guiding historical analogy for our current predicament.
The Bush administration is determined to convince the public that it is 1938 in Iran and Mahmoud Ahmadinejad is Hitler. Or that it's 1917 and Osama bin Laden is a new Lenin. Others see Spanish Civil Wars in Iraq or on Lebanon's southern border. I shudder to count all the folks who claim that Iraq is Vietnam.
For many liberals of a certain generation, Vietnam is a universal peg, fitting perfectly into analytical holes of any shape. Indeed, the closest thing we get to a neat left-right divide on foreign policy these days is between those who see Vietnam as the Rosetta stone of international conundrums and those who see early 20th-century Europe as the universal translator.
These analogies have some persuasive power. I am particularly convinced the White House is correct that ignoring the evil of jihadism - whatever its historical analogues - will be repaid with tragedy.
Nonetheless, there are two problems with historical cherry-picking. The first is our collective ignorance about history. As a culture, we have a tendency to look for our car keys where the light is good. Our usable past is the past that is illuminated to us. One reason we leap to analogies about World War II and the Cold War is that it's the only history most of us know. It's telling that military histories about World War II (the "good war") vastly outnumber all others. People don't call the History Channel the Hitler network for nothing. Meanwhile, Vietnam (the "bad war") feels like only yesterday to baby boomer liberals, so they have a tendency to see LBJ, Robert McNamara or other ghosts of "quagmires" past haunting the Bush White House.