ARISTOTLE VERSUS PHILOPONUS: A FUNCTIONAL APPROACH TO THE INTUITIVE PHYSICS OF PROJECTILES Nuno De Sá Teixeira *1 & Armando Mónica Oliveira *2 * Institute of Cognitive Psychology, University of Coimbra 1 nuno_desateixeira@fpce.uc.pt 2 l.dinis@fpce.uc.pt Abstract Intuitive physics is a popular field of research within cognitive psychology which addresses the common-sense beliefs about the physical world, particularly about classical mechanics. An influential stream of research argues for the striking resemblance between common-sense beliefs and those embodied in pre-Newtonian theories, such as the medieval physics of impetus. In this study, two early algebraic proposals for the relation between the force applied to an object, the resistance to its motion and its resulting velocity are compared, the first one derived from Aristotle, the other set forth by Philoponus (VIth century). The methodology of Information Integration Theory was used, revealing a dividing cognitive integration rule in agreement with Aristotle’s proposal. The significance of this finding is discussed through a suggested link with the mental models framework. Intuitive Physics has earned an honorable place within cognitive psychology (see McCloskey, 1983a). As a field of study, it addresses the spontaneous representations of the physical world, especially those concerning the phenomena described by classical mechanics. One advantage of intuitive physics regarding other domains of cognitive psychology is the possibility to assess the correctness of cognitive representations against a non arbitrary criterion, which is provided by Newtonian Mechanics (Anderson, 1981). This capability soon led to the finding of systematic and persistent (to the point of resisting formal instruction) divergences between our intuitions and the physical reality (Trowbridge & McDermott, 1980; Champagne, Klopfer & Anderson, 1980; Caramazza, McCloskey, & Green, 1981; Clement, 1982; McCloskey, 1983a; 1983b; diSessa, 1998). Examples of commonly diagnosed misconceptions include the “straight-down belief” for the path of an object dropped from a moving carrier, the assumption of a curvilinear impetus, or the notion that heavy bodies fall more rapidly than light bodies. Two major sorts of explanation have been proposed for these mistaken beliefs. One of them invokes the processing limits of our cognitive apparatus, particularly when it comes to the integration of multiple dimensions (Kayser, Proffit , & Anserson, 1985); in the version given by Proffit and Gilden (1989), accurate dynamic judgments can only be obtained for events so simple that one single category of information (dimension) is all that needs to be considered. The other emphasizes the non random character of these errors to defend their subsumption under coherent naïve theories of the physical world, bearing moreover epistemological parallels to pre-Newtonian views such as the medieval theory of impetus (McCloskey, 1983a) or Aristotelian physics (Champagne, Klopfer, L. & Anderson, 1980). Given the centrality of mechanics to both modern and ancient physics, discussion has largely been held around our intuitions of motion and, particularly, of the motion of projectiles. The common trait to all pre-Newtonian theories of movement is that motion, differently from rest, requires a cause (which violates Newton’s first law). Aristotle conceived of that cause as external, thus distinguishing between the moving body (the motus) and the 315