Mr. Romney was tagged as a wonk because he "immerses himself in data." But one thing immersion can do that casual "gut" proceedings can't is let you know when the data don't provide an answer, even if people are telling you it does.

McCain’s absolutist position on the surge, while admirable in his support of our troops, is almost the dictionary definition of ideologue. It’s not the facts that convinced McCain that the surge is working, but the idea itself. In McCain’s mind it would be working whether or not the facts showed it, because the idea is right in his mind. This is the same kind of stubbornness that has kept him supporting “comprehensive immigration” when the facts don’t support him. Similarly campaign finance reform has been an abject failure, but McCain still supports it because the idea is right, in spite of the facts. Likewise McCain has come to the correct conclusion on the surge, not lead by the facts, but lead only by the idea. McCain is right more out of luck than any sort of analytical process that lead him to the right conclusion. Such a blind adherence to ideas is unsupportable.

It perhaps takes somebody steeped like Mr. Romney in real-world analytics to find a footing against the media tide. But the fact remains: The push toward warming that CO2 provides in theory is no reason to presume in confidence that CO2 is actually responsible for any observed warming in a system as complex and chaotic as our atmosphere.

In his climate speech on Monday, Mr. McCain exhibited (as the press usually does) a complete lack of consciousness of the fact that evidence of warming is not evidence of what causes warming. Yet policy must be a matter of costs and benefits, adjusted for the uncertainties involved. Which brings us to today's irony: He who finds a six-figure earmark an affront to humanity is prepared to wave through a trillion-dollar climate bill without, as far as anyone can tell, a single systematic thought about costs and benefits.

Mr. McCain argues that green energy mandates will leave us better off whether or not man-made global warming is real. This is an error that Mr. Romney wouldn't make – and one Al Gore makes all the time.

Labels: global warming, John McCain