The psychological study of thinking has both a very long and a very short history. Its long aspect comes from its antecedents in philosophy, where ideas can be traced back to classical antiquity: Aristotle, in particular, casts a shadow stretching over more than 2000 years. On the other hand, the psychology of human thinking, as a branch of cognitive psychology, can hardly be older than cognitive psychology itself, and the birthday of the latter is often located in the late 1950s (see e.g. Baars, 1996). In fact, we can look to even more recent times for the beginnings of a true cognitive psychology of thinking, to Wason and Johnson-Laird’s Psychology of Reasoning: Structure and Content, published in 1972.