The 44 Dumbest U.S. Presidents Ranked By IQ

8. Zachary Taylor: 139.8

Just one decimal point below Harding, three other candidates share the 139.8 IQ spot. Taylor, however, could excuse his lower IQ with his limited education. Never attending college and never practicing law, Taylor was a presidential outlier. Instead, he spent four decades in the Army where he quickly rose through the ranks.