REASONING, DECISION-MAKING AND RATIONALITY

It is argued that reasoning in the real world supports decision making and is aimed at the achievement of goals. A distinction is developed between two notions of rationality: rationality1 which is reasoning in such a way as to achieve one's goals - within cognitive constraints - and rationality2 which is reasoning by a process of logic. This dicho tomy is related to the philosophical distinction between practical and theoretical reasoning. It is argued that logicality (rationality2) do es not provide a good basis for rationality1 and some psychological re search on deductive reasoning is re-examined in this light. First, we review belief bias effects in syllogistic reasoning, and argue that th e phenomena do not support the interpretations of irrationality that a re often placed upon them. Second, we review and discuss recent studie s of deontic reasoning in the Wason selection task, which demonstrate the decision making, and rational1 nature of reasoning in realistic co ntexts. The final section of the paper examines contemporary decision theory and shows how it fails, in comparable manner to formal logic, t o provide an adequate model for assessing the rationality of human rea soning and decision making.