Impetus Then and Now: A Detailed Comparison between Jean Buridan and a Single Contemporary Subject

Conceptual change in mechanics can neither be understood nor facilitated without knowledge of the content and structure of the common sense beliefs with which it starts. However, empirical investigations of common sense beliefs about physical motion have not yet produced a consensus about the correct characterization of such beliefs. Different researchers have proposed different hypothesis about the content of common sense beliefs, about their relations to historical theories in physics, and about the reasoning processes available to scientifically naive persons. The empirical validity of the alternative claims are difficult to appraise because many published reports give little information about how well the various hypotheses account for the data on which they are said to be based. In this paper we apply a four-step method to the analysis of a single interview protocol in order to answer three questions a What, exactly, does the subject believe about physical motion b What is the relation between the subjects common sense beliefs and the impetus theory of physical motion formulated by the philosopher Jean Buridan in the fourteenth century and c What theoretical reasoning processes, if any, does the subject have at her disposal for reasoning about physical motion kt