This cruelest of years has claimed the life of another consequential scholar whose passing warrants some reflection. James Flynn, who died last week at 86, was an American social scientist born in Washington and educated at the University of Chicago. He spent most of his academic career on the other side of the planet, at the University of Otago in southern New Zealand. Flynn specialized in the study of mental tests and human intelligence, and he distinguished himself by bringing far more light than heat to this fraught debate. Many earlier researchers of group differences in mental performance were convinced...