What makes belief-desire psychology a "commonsense' or "folk' psychology? Part of the answer is that it is to be contrasted with a scientific psychology. The latter consists of a collection of evolving theories and hypotheses, formulated by professional scientists and tested via a range of explicit methods and experimental techniques. Knowledge of its various sub-disciplines, in conjunction with the relevant practical expertise, is acquired through a lengthy process of explicit training. FP, in contrast, is something that all typical people start employing at around the same early age, without any training. And it arises and persists in much the same form regardless of what one might know about scientific psychology. Hence it is not a "pop science' acquired by educated non-scientists but an understanding that is possessed by educated and uneducated alike.