Further Thoughts on Anachronism: A Presentist Reading of Newton’s Principia

This chapter is an exercise in anachronism. I read a hitherto unnoticed corollary in Newton’s Principia availing myself of concepts and results that were obviously unavailable to the author. I contend that even extreme forms of anachronism can be helpful in the historical interpretation of past mathematical texts. I also claim that such anachronistic readings must be followed by an attempt to capture the differences between past and present mathematics. The text I analyze is Proposition 41, Book 1, and its three corollaries (especially, the second one), which are part of a set of propositions where Newton deals with the motion of a body accelerated by a central force.