Without Good Reason

Do decades of laboratory studies show that people are irrational? Researchers have reported systematic errors in areas such as logical deduction, reasoning about probabilities, judging how alike things are, and assessing risk. Some philosophers have replied that rationality is part of what it means to be human, so no experiment could ever reveal a lack of it. Whether the experimental results can bear the weight placed on them is the question at the heart of the dispute.

Stein examines the competing models of rationality around which the debate turns and evaluates the empirical evidence that has been used to claim people are irrational. He follows the argument through both philosophy and cognitive science, weighing the positions on each side.

His answer is that rationality cannot be settled by analysing the concept alone and must instead be resolved through empirical investigation, using the strongest tools that modern cognitive science provides. He then extends this view to knowledge itself, arguing that empirical findings matter to epistemology and that the theory of knowledge should be naturalised.