Historical and Philosophical Details on Leibniz’s Planetary Theory as Physical-Structural Model

In February 1689 Gottfried Wilhelm von Leibniz (1646–1716) published the Tentamen de motuum coelestium causis in Acta Eruditorum. This work deals with a planetary model. This essay is not a mere formal–or–virtuosic mathematical exercise only. It represents a significant conceptualization within a general physical theory that Leibniz was going to construct. It is well known that Leibniz rejected the action at a distance. He was convinced that each interaction between bodies should be explained by means of mechanical causes only. However, we remark: 1) he was a contemporary of Huygens and Newton and – obviously – he had to take into account Newton’s results; 2) he thought that also the final causes should play a role in the physical explanations. In fact, his introduction of the vis viva is connected to the idea that the final causes could play a role within physics. This fact offers an interesting and stimulating picture, which has fertile consequences both in his planetary model and in the role played by planetary model in his entire theoretical system. In order to inquiry historically and philosophically Leibniz’s planetary model, we introduce the epistemological key–notion of the physical–structural model. This is connected with Leibniz’s attempt of edifying a physical system: observation, physical quantities and mathematical interpretations are involved in such model. Within this context both the effects of the most important actions (specifically gravity) and physical causes were dealt with by Leibniz. In this paper, we present and discuss, by means of the above key–concept, Leibniz’s planetary model. This paper is part of a larger research programme (RP) concerning the relationship between physics and mathematics in the history and philosophy of science.