Every year the College Board, the organization that oversees Advanced Placement and SAT exams, publishes an alarming graph. It depicts college tuition soaring like a rocket into the sky, although the trajectory has leveled off in recent years. The implicit message is clear: college has become increasingly unaffordable, forcing too many young adults to take on stratospheric debts. But a pair of academic economists – including Sarah Turner of the University of Virginia – are flipping this message on its head. They argue that higher tuition prices have actually made college cheaper for many lower...