Structures of argument and concepts of force in the aristotelian mechanical problems

摘要

I argue that the main goal of the Mechanical Problems, a short treatise transmitted in the Corpus Aristotelicum, is to explain the working of technology in terms of the concepts of Aristotelian natural philosophy. The author's explanatory strategy is to reduce the thirty-five "problems" or questions that he discusses to one or more of three simple models: the circle, balance, and lever. The conceptual foundation of this reduction program is a principle concerning circular motion, viz. that a point on the circumference of a larger circle moves more quickly than one on a smaller circle, assuming that the circles turn about the same center at the same angular speed. I analyze the author's argument for this principle and his application of it throughout the text, especially to the analysis of the lever. The main conclusions are (1) that the author's justification of the circular motion principle is based on an innovative geometrical analysis of motion, not on a highly theoretical conceptualization of force; and (2) while the author is aware of a reciprocal relationship between weights and distances from the fulcrum in the case of the lever, his explanation of this fact makes no reference to the conditions for static equilibrium.