The Ontological Coherence of Intuitive Physics

diSessa’s theory is a deeply articulated, thought-provoking account of the structure of intuitive physics knowledge. We agree with the spirit of the theory in most regards, with one or more important points of departure, which we discuss here. Specifically, we believe that there is more structure in intuitive knowledge than diSessa has suggested and propose a theory of ontological categories as an alternative to his theory of knowledge fragments. Indeed, diSessa briefly entertains the notion of ontological explanations in the context of exploring theoretical alternatives to his own view but provides only a sketch of the basic ideas. Because diSessa could not locate any substantial published defense of this position, we provide a brief description of our own version of this alternative theoretical view, which is either recently published (Chi, 1992) or forthcoming (Chi, Slotta, & de Leeuw, in press). But first, we highlight several of his assertions and then evaluate these assertions in the context of the ontological theory. Finally, we provide a short discussion of some preliminary empirical findings of our own that support the ontological theory.