Ah, but it’s gauche to say anything about it. Except that Sullivan points to an article indicating why it might be very important indeed:

In 2002, an estimated 5.4 million people (22.2%) in the United States age 71 years or older had cognitive impairment without dementia. Furthermore, the Editors note the following: This study of 856 individuals from the national Health and Retirement Study found that 22% of adults age 71 or older had cognitive impairment that did not reach the threshold for dementia. Annually, about 8% of those with cognitive impairment without dementia died and about 12% progressed to dementia. Implication  Cognitive impairment without dementia probably affects a large segment of the elderly population.

Writes Sullivan:

Mild cognitive impairment might affect attention, language, judgment, memory, reading, or writing. It may be noticeable to the individual or to other people, but it does not severely impair activities of daily living. Few studies examine the frequency and course of mild cognitive impairment in older adults. But couuld it affect decison-making in highly complex areas where answers require strong mental skillls and swift assimilation of new facts. Under the pressure of a campaign or public office, this is not easy. Running a war with potential terror strikes imminent may be not a time when you hope your president isn’t having an off-day and a litte confused - Shiites? Sunni? Which are the bad guys?

We’ve seen several gaffes from McCain that indicate some of this might be happening. Gaffes happen with all candidates, of course.

But has governing this country ever been more complex? In terms of our foes, not states but non-state actors who could literally strike any place at any time; the bundled securities at the heart of many of the market’s problems; the technology, which McCain has already stated he doesn’t really grasp.

In any environment, but particularly this environment, cognitive ability - and the degree to which age can inhibit it - is a legitimate factor. Age alone shouldn’t be the sole factor, unless we have definitive evidence that McCain is impaired, or any candidate is impaired. But to say age is irrelevant - or that it’s simply rude to talk about it - is to try and do an end run. We know why the Grand Old Party might want to do that. But from the nation’s perspective - how wise is it?