Published online by Cambridge University Press: 09 April 2001
I discuss an aspect of individual differences which has not been considered adequately in the target article, despite its potential role in the rationality debate. Besides having different intellectual abilities, different individuals may produce different erroneous responses to the same problem. In deductive reasoning, different response patterns contradict deterministic views of deductive inferences. In decision-making, variations in nonoptimal choice may explain successful collective actions.