Principles in Newton's Natural Philosophy

Abstract

Newton’s great work of ‘rational mechanics’ is supposedly about principles. They’re even in the title: Philosophiae naturalis principia mathematica. However, Newton’s use of the term ‘principle’ appears to be unsystematic and opaque. Was ‘principle’, then, just a ‘buzz-word’ for Newton? Or is there something important underlying his use of the term? I support the latter. While the term ‘principle’ did not play a central role in Newton’s methodology (indeed, I will suggest that hypotheses and theories are the important concepts for Newton), once we disambiguate his usage, something systematic arises. What it takes to be a principle, by Newton’s lights, is to play a certain kind of role.