ABSTRACT. Bergeson et al. claim that place value is extremely significant in mathematical learning. Tall focuses attention on psychological evidence of relevance to advanced mathematical thinking. English contends that complexity is the study of systems of interconnected components whose behavior cannot be explained solely by the properties of their parts but from the behavior that arises from their interconnectedness. Feest suggests that psychology can provide autonomous explanations: in order for such explanations to be good explanations, they have to appeal to the intervening variables that realize the behavioral dispositions in questions.