Erik Curiel


Ludwig-Maximilians-Universität München

On Newton's Third Rule of Reasoning in Philosophy, “the Universal Qualities of All Bodies Whatsoever," and the Speciation of Physical Systems

At the beginning of Book Three of Principia, Newton proposes his “Rules of Reasoning in Philosophy”. Rules I, II and IV are incisively brief, both in the statement of the rules themselves and in their attendant scholia. Rule III, by contrast, is considerably more com- plex in its statement, and bears a scholium more than 6 times the length of the scholia of the other three rules combined. Clearly, something rich is in the offing. I quote the rule in full: The qualities of bodies, which admit neither intensification nor remission of