Keywords: Intentional System Theory; Rationality Assumption; Human Irrationality.
In "Three Kinds of Intentional Psychology", the philosopher Daniel Dennett has proposed to legitimize the use of the intentional vocabulary in cognitive psychology by building a new sort of theory, the so-called intentional-system theory. The aim of the theory is to provide belief/desire explanations and predictions of human behaviour based on a fundamental assumption of (idealized) rationality. Stephen Stich has famously formulated a series of objections to Dennett's proposal based on the observation that the human cognitive system is affected by systematic irrationality. In this paper, I critically analyse the debate between Dennett and Stich on human rationality in light of the most recent findings in the field of the (evolutionary) psychology of reasoning.