The excuses for President Obama’s shockingly weak performance in last week’s presidential debate are taxing the imaginations of the left. We’re told President Obama doesn’t like confrontations because he wants to be president of all the people (Paul Krugman); he doesn’t watch enough MSNBC (Chris Matthews); he’s a great thinker but a so-so debater (David Remnick); he may actually need that teleprompter (Bill Maher); and of course everyone’s all-time favorite: it was the altitude (Al Gore). On the right, the argument has been that the media has coddled Obama — so much so that he is unable to respond effectively to the challenges presented by Romney.

Few people, however, even on the right, have cited the two most plausible explanations for Obama’s failure, although these are staring them in the face.

First, in a debate that was supposed to elucidate the differences between the candidates, Obama had few accomplishments with which to differentiate himself from Romney. He couldn’t trumpet Obamacare, since most Americans want it repealed. He couldn’t cite the success of the $800 billion stimulus in bringing down unemployment, because most Americans view it as a failure. He couldn’t point out that his housing policies have awakened the sleeping giant of the housing market, because they haven’t. He couldn’t note that he has endorsed the Simpson-Bowles Commission’s deficit-reduction proposal, because he hasn’t. His whole campaign has been nothing more than a series of attacks on Mitt Romney, and more negative attacks are not what independents want out of a presidential debate.

But there is another possible explanation for President Obama’s weak debate performance. Perhaps Obama isn’t the remarkable intellect his supporters believe him to be. He’s written two autobiographical books, and he clearly has a gift for delivering prepared speeches. But does he really know anything beyond what his staff prepares? His college and law school grades are under seal, and the media always showed less interest in them than in Romney’s tax returns. He never ran a business, so its success could not be used as an index of his abilities. He got a law degree but never distinguished himself as a lawyer, wrote a winning brief or made a brilliant oral argument in an appeal. He was a U.S. senator for four years and an Illinois state senator for eight, but — to say the least — he did not distinguish himself by proposing significant legislation in either chamber.

So maybe he’s not the intellectual giant that his supporters and the media have supposed. We’ll know more after the next debate, but as a working hypothesis, this idea — after four years of failure and drift — certainly has some surface plausibility.

Peter J. Wallison is the Arthur F. Burns Fellow in Financial Policy Studies at the American Enterprise Institute.