No doubt you know several folks with perfectly respectable IQs who just don’t seem all that sharp. The behavior of such people tells us that we are missing something important by treating intelligence as if it encompassed all cognitive abilities. I coined the term “dysrationalia” (analogous to “dyslexia”), meaning the inability to think and behave rationally despite having adequate intelligence, to draw attention to a large domain of cognitive life that intelligence tests fail to assess. Although most people recognize that IQ tests do not measure important mental faculties, we behave as if they do. We have an implicit assumption that intelligence and rationality go together—or else why would we be so surprised when smart people do foolish things?