Naive psychology depends on naive physics

How do humans make sense of other people: entities who are simultaneously psychological beings and physical objects? Across the cognitive sciences, including psychology, anthropology, philosophy, and neuroscience, scholars have puzzled over the origins and structure of our understanding of the physical world on the one hand, and the psychological world on the other. Each of these research areas has accumulated evidence that these two domains of thought are independent, modular systems. We disagree. Starting in infancy, and indeed throughout our lives, our psychological reasoning (naive psychology) depends on inputs from physical reasoning (naive physics). In this paper, we first review evidence for the modularity hypothesis from developmental psychology, cross-cultural research, cognitive neuroscience, and neuropsychology, and argue that this work provides evidence for domain-specificity (that naive psychology and physics are conceptually distinct) but not for modularity (that these two abilities are informationally encapsulated from each other). To the contrary, we use evidence from each of these disciplines, and research from computational cognitive science, to argue that naive psychology and physics constitute parallel and integrated systems in human minds and brains. We end by laying out a research program to investigate this integration.