Contemplating President Obama's rise, sometimes you wonder, does this guy lead a charmed life or what? Six years ago, he's a state senator and part-time law professor on a long-shot bid for the U.S. Senate, when his two main rivals helpfully implode in scandals. He's in the Senate barely long enough to figure out where they keep the paper clips, then -- bam! -- he's president of the United States. Nine months later, the Nobel Committee hands him the Peace Prize for ... for ... well, I'm not sure either.

So it's hard to be shocked that just 18 months into his term, a team of presidential scholars has decided Barack Obama's already the 15th best president we've ever had.

On Thursday, the Siena Research Institute released its latest presidential rankings list, based on a poll of 238 academics. Siena's survey reflects academia's typical bias toward power-hungry activists like Woodrow Wilson and the two Roosevelts.

"Do-nothing" presidents need not apply. (Poor William Henry Harrison, who keeled over a month after his inauguration, is ninth worst).

Say what you will about 44, but after a ramming through a $787 billion "stimulus" package and a massive new health care entitlement, he's anything but a "do-nothing" president -- which helps explain his high marks from Siena.

One of Siena's criteria is "willingness to take risks." That's not the first quality I'd look for when picking someone who'll have access to nuclear weapons, but I suppose it makes things more exciting -- a high priority for the rankers.

"We long ago concluded that no American president would be reported as great," the survey's co-director reports, unless he "surmounted at least one major obstacle during his presidency." "Sorry, Calvin Coolidge," the Daily Caller's Chris Moody cracked.

"If you see ten troubles," Coolidge (Siena's No. 29) once remarked, "nine will run into the ditch before they reach you." If he had napped less and started more fights, maybe he would have graduated in the top half of the class.

Academia's liberal bias skews the presidential rankings, to be sure, but it turns out that right-wing academics swoon for imperial presidents as well. The Wall Street Journal and the Federalist Society proved that with a 2005 ranking using an ideologically balanced panel. According to self-identified conservatives in the WSJ/Fed Soc poll, FDR -- the court-packer, architect of the welfare state, and jailer of more than 100,000 innocent Japanese-Americans -- was the fifth-best president in American history.

"Fortunately," writes economic historian Jeffrey Rogers Hummel, "libertarians have begun to challenge the statist bias of presidential ranking." In 2001, two Ohio University economists developed a rough measure based on reductions in the size of government. Warren Harding (Siena's third worst) came in first, having cut federal spending in half during his tenure.

Ivan Eland's 2009 book "Recarving Rushmore" rates the presidents on how effectively they promoted peace, prosperity and liberty -- standards that keep faith with goals set out in the Constitution's Preamble: "insur[ing] domestic Tranquility" and "secur[ing] the Blessings of Liberty." (I know, boooring.)

Eland's revamped Rushmore would feature the visages of John Tyler, Grover Cleveland, Martin Van Buren and Rutherford B. Hayes -- presidents who are lucky to get junior high schools named after them, let alone monuments raised in their honor.

But there's much to be said for those allegedly "unheroic" chief executives who see themselves as guardians of limited, constitutional government. The opposite approach has saddled us with a national debt that, according to the International Monetary Fund, will be larger than the entire U.S. economy by 2012.

In a time of relentless -- and destructive -- presidential activism, we may yet come to appreciate the virtues of thinking small.

Examiner Columnist Gene Healy is a vice president at the Cato Institute and the author of "The Cult of the Presidency."