Pierre Boulos

William Harper has recently proposed that Newton's ideal of empirical success as exemplified in his deductions from phenomena informs the transition from natural philosophy to natural science. This dissertation examines a number of methodological themes arising from the Principia and that purport to exemplify Newton's ideal of empirical success. Among these themes is the method of answering important theoretical questions empirically by measurement from phenomena. According to Newton's ideal, a successful theory has its parameters measured by the phenomena it purports to explain. The ideal of empirical success is not limited to prediction, but also generates reliable measurements of the parameters of the phenomena. ;Newton's Principia exemplifies deductions from phenomena where a higher level theoretical claim is inferred from certain other high level theoretical principles along with phenomena. Newton established that a measure of the rate of orbital precession could sensitively measure the exponent of the force law. In the moon-test, Newton turned the theoretical question regarding the measure of the force holding the moon in her orbit into an empirical question of measurement of the length of a seconds pendulum on earth. Two different phenomena are giving agreeing measurements of the same inverse-square centripetal force field. The agreement in measured values is a higher level phenomenon which relates the two phenomena in question. Newton's model of evidential reasoning exploits these agreements in such a way that the stakes are raised for rival theories. ;The work done on the lunar perturbation problem forms the focus of this project. In considering the effect of the sun on the moon in her orbit, Newton was able to account for only half of the observed lunar precession. The solution to this problem came in the late 1740s and early 1750s through the work of Clairaut, d'Alembert, and Euler. The zero precession left over after the effect of the sun on the lunar orbit had been correctly solved removed impediments to the acceptance of Newton's system. The solution exhibited Newton's stronger ideal. ;Newton's ideal of empirical success did not immediately become part of the practice of natural philosophy. When one traces the developments of Euler, Clairaut, and others working on lunar precession and perturbation theory, these developments exhibit a better realization of Newton's ideal. Thus a good candidate for exploring the entrenchment of Newton's ideal is the solution of the lunar perturbation problem. The question is "when did it occur?" We will examine whether Euler had in mind this stronger ideal after he first denounced the Newtonian system for failing to solve the lunar problem and then accepted it largely based on Clairauts solution to the problem. Although this stronger ideal is exemplified in the solution to the lunar perturbation problem, it is not clear that Euler exhibits an understanding and an awareness of the kind of evidential reasoning which drives Newton in his own work. Newton's ideal suggests that a priori metaphysical commitments ought not to drive scientific investigations. Although Euler is willing to bracket an a priori metaphysical commitment to an aether theory, he nonetheless seems to accept the inverse-square law on hypothetico-deductive grounds.