Some theoretical and practical implications of defining aptitude and reasoning in terms of each other

Stanovich & West continue a history of norm-setting that began with deferen ce to reasonable people's opinions, followed by adherence to probability th eorems. They return to deference to reasonable people, with aptitude test p erformance substituting for reasonableness. This allows diem to select inde pendently among competing theories, but defines reasoning circularly in ter ms of aptitude, while aptitude is measured using reasoning.