ABSTRACT
The study of thinking and reasoning in humans can accurately be described as the study of the nature of intelligence. The work described falls, however, into a quite different tradition from the psychometric study of individual differences in intelligent performance that is usually referred to as the psychology of intelligence. A person has a problem whenever he or she wishes to achieve a goal and is unable to proceed immediately to do so. Reasoning is the process of drawing conclusions or inferences from given information. An important distinction is that between deductive and inductive inference. Deductive reasoning involves drawing conclusions that are logically valid, that is, they necessarily follow from the premises on which they are based. If human thinking is rational - and the success of the species suggests that it should be - then that rationality is highly constrained by capacity to process information.
