Credentialed persons, credentialed knowledge

The vast experimental literature on human error agrees with history of medicine, folklore, and superstition in discrediting knowledge claims bared solely on anecdotal impressions. Since clinical experience consists of anecdotal impressions by practitioners, it is unavoidably a mixture of truths, half-truths, and falsehoods. The scientific method is the only known way to distinguish there, and it is both unscholarly and unethical for psychologists who deal with other persons' health, careers, money, freedom, and even life itself to pretend that clinical experience suffices and that quantitative research on diagnostic and therapeutic procedures is not needed. Disputes about philosophy of science (e.g., logical positivism) are irrelevant to this issue, which is simply one of distinguishing knowledge claims that bring reliable credentials and others that do not.