 But an opponent might respond that interpreting ordinary speakers as uttering truths concerning logic can look rather similar to attributing true beliefs about quantum mechanics to infants. As the Wason selection task experiments have shown in psychology, even educated speakers will fail to act as if the argument form modus tollens is correct in certain circumstances (Wason 1966, 1968; Cosmides 1989). Though the most charitable interpretation of their behaviour might be that they do not mean by ‘follows from’ what the experimenters meant by it, by far the most natural understanding of what is going on here is that the subjects make mistakes. To interpret them as meaning something different by misses what these experiments reveal about human reasoning, and fails to explain why the subjects later judge that their earlier answers were wrong. 