Noted intellectual and Twitter phenomenon Chuck Grassley has found himself in a bit of a dust-up after calling President Obama “stupid” in a tweet over the weekend. The Republican Senator was referring to Obama’s comments about healthcare reform and the Supreme Court, but his rudeness raises a bigger question: When it comes to brains, how does the president stack up against his predecessors?

A survey of presidential scholars gives some insight. In a survey of 238 experts conducted by Siena College, Obama was ranked eighth among all presidents in the intelligence category. And for the curious, a 2006 paper presents a more extensive ranking of the presidents by various intelligence factors, including estimated IQ and a rough measure called “Intellectual Brilliance.” By those metrics, Thomas Jefferson and John Quincy Adams are among the all-time leaders. Among recent presidents, George W. Bush was estimated to be pretty intelligent compared the general populace, but “near the bottom of the distribution” among presidents. Among twentieth-century presidents, though, Bush still edged out Warren Harding—and Calvin Coolidge, too, depending on the metric.