In the spring of 1974, New Times magazine ran a cover story that listed the 10 dumbest members of Congress. At the top of the list was Virginia Senator William Scott, who’d won the designation for, among other things, dismissing talk during a briefing about missile silos by saying, “I’m not interested in agriculture. I want the military stuff.” The senator, shrewdly concluding that this was not a politically helpful story, promptly called a news conference to deny it. (He retired after one term.)

In September 1987, the presidential campaign of Senator Joe Biden, rocked by charges of plagiarism, was hit by new stories from his law school days. Pressed by a questioner at a gathering in Claremont, New Hampshire, Biden said:

“I think I probably have a much higher IQ than you do, I suspect. … I won the international moot-court competition … ended up in the top half of my class. I was the outstanding student in the political science department at the end of my year. I graduated with three degrees from undergraduate school and 165 credits — only needed 123 credits. And I would be delighted to sit down and compare my IQ to yours.”

A few days later, after it turned out these boasts were essentially untrue, Biden withdrew from the presidential race.

Can we conclude from these two examples that it’s dangerous for politicians to be defensive about their intelligence? Do these stories suggest that President Donald Trump may be on shaky ground when he offers to “compare IQ tests” with a secretary of state who has refused to deny having called the president a “moron"?

There may be a more useful question to ask: Does it matter how smart the president is? What does a leader’s IQ tell us about how effectively he or she can do the job? In his book “Outliers,” Malcolm Gladwell suggests that it may not matter much beyond a certain threshold. “The relationship between success and IQ works only up to a point,” he writes. “Once someone has reached an IQ of somewhere around 120, having additional IQ points doesn’t seem to translate into any measurable real-world advantage.” A contrary view, at least about presidents, comes from ex-Senator Gary Hart, who argued that “it takes a pretty keen mind, honed by study, travel, experience and exposure to competing ideas, to form good judgment and to know whom to trust on complex substantive issues.” (To which every reader is now shouting, “How keen an intellect does it take not to pose for a picture on a boat called the ‘Monkey Business’ with a young lady perched on your lap?”) ...