In this essay I argue against I. Bernard Cohens influential account of Newtons methodology in the Principia: the Newtonian Style. The crux of Cohens account is the successive adaptation of mental constructs through comparisons with nature. In Cohens view there is a direct dynamic between the mental constructs and physical systems. I argue that his account is essentially hypothetical-deductive, which is at odds with Newtons rejection of the hypothetical-deductive method. An adequate account of Newtons methodology needs to show how Newtons method proceeds differently from the hypothetical-deductive method. In the constructive part I argue for my own account, which is model based: it focuses on how Newton constructed his models in Book I of the Principia. I will show that Newton understood Book I as an exercise in determining the mathematical consequences of certain force functions. The growing complexity of Newtons models is a result of exploring increasingly complex force functions (intra-theoretical dynamics) rather than a successive comparison with nature (extra-theoretical dynamics). Nature did not enter the scene here. This intra-theoretical dynamics is related to the autonomy of the models.

}, issn = {0269-8595}, author = {Ducheyne, Steffen} }