Kevin Drum lists the reasons why Perry won't be president. Among them:
He's too dumb. Go ahead, call me an elitist. I'm keenly aware that Americans don't vote for presidents based on their SAT scores, but everything I've read about Perry suggests that he's a genuinely dim kind of guy. Not just incurious or too sure about his gut feelings, like George Bush, but simply not bright enough to handle the demands of the Oval Office. Americans might not care if their presidents are geniuses, but there's a limit to how doltish they can be too.
I don't think this is elitist. I think it's wrong. I don't know when people got it in their heads that there's a Wonderlic test for the presidency, but it's a notion that should be done away with immediately.
I'm sure there some level of imbecility which would be too much for Americans, but it seems that the ability to understand and speak to the ambitions of a critical mass of the electorate is much more important. Intelligence might help that effort. But empathy--or at least the ability to communicate empathy--with your audience seems much more important.
This is to say nothing of the rules of the game. I'm sure Mark Penn is plenty smart. He still didn't understand proportional allocation.
Intelligence is overrated.