Thomas Hobbes based his natural philosophy on definitions and general principles of matter in motion, which he refrained from calling “laws of nature.” Across the channel, René Descartes had presented his own account of matter in motion in such a way that laws of nature play a central causal-explanatory role. Despite some notable differences in the two systems of natural philosophy, the content of the three Cartesian laws of nature is shared by Hobbesian principles of motion. Why is it the (...) case that Hobbes never ‘transferred’ the concept of law of nature from the sphere of civil society to the realm of nature? What is the status of the Hobbesian principles of motion if they are not laws? Answering these questions is the main aim of this article. It is shown that Hobbes made available an importantly different and genuinely original way to do natural philosophy, which renders it free of metaphysics and eschews the need to ground it in anything other than ‘natural reason’. Briefly put, Hobbes took the category of ‘laws of nature’ to involve commitments that cannot be met in the natural world, unless natural philosophy loses its autonomy from theology and metaphysics. (shrink)

The history of the Parallelogram Rule for composing physical quantities, such as motions and forces, is marked by conceptual difficulties leading to false starts and halting progress. In particular, authors resisted the required assumption that the magnitude and the direction of a quantity can interact and are jointly necessary to represent the quantity. Consequently, the origins of the Rule cannot be traced to Pseudo-Aristotle or Stevin, as commonly held, but to Fermat, Hobbes, and subsequent developments in the latter part of (...) the seventeenth century. (shrink)

One of the chief concerns of the young Descartes was with what he, and others, termed “physico-mathematics”. This signalled a questioning of the Scholastic Aristotelian view of the mixed mathematical sciences as subordinate to natural philosophy, non explanatory, and merely instrumental. Somehow, the mixed mathematical disciplines were now to become intimately related to natural philosophical issues of matter and cause. That is, they were to become more ’physicalised’, more closely intertwined with natural philosophising, regardless of which species of natural philosophy (...) one advocated. A curious, short-lived yet portentous epistemological conceit lay at the core of Descartes’ physico-mathematics—the belief that solid geometrical results in the mixed mathematical sciences literally offered windows into the realm of natural philosophical causation—that in such cases one could literally “see the causes”. Optics took pride of place within Descartes’ physico-mathematics project, because he believed it offered unique possibilities for the successful vision of causes. This paper traces Descartes’ early physico-mathematical program in optics, its origins, pitfalls and its successes, which were crucial in providing Descartes resources for his later work in systematic natural philosophy. It explores how Descartes exploited his discovery of the law of refraction of light—an achievement well within the bounds of traditional mixed mathematical optics—in order to derive—in the manner of physico-mathematics—causal knowledge about light, and indeed insight about the principles of a “dynamics” that would provide the laws of corpuscular motion and tendency to motion in his natural philosophical system. (shrink)

ArgumentAccording to a long-standing interpretation which traces back to Max Jammer'sConcepts of Force(1957), Ruggiero G. Boscovich would have developed a concept of force in the tradition of Leibniz's dynamics. In his variation on the theme, basic properties of matter such as solidity or impenetrability would be derived from an interplay of some “active” force of attraction and repulsion that any primary element of nature (“point of matter” in Boscovich's theory) would possess. In the present paper I discuss many flaws of (...) this interpretation and argue for an alternative point of view, according to which the crucial aspect in the development of Boscovich's natural philosophy is his early definition of forces as “mathematical determinations” to have a certain state of motion. This is consistent with a Newtonian background and has as its epistemological consequence a certain agnosticism about the nature of forces and a “mathematical neutralism” (mathematics as a neutral tool, allowing for a plurality of interpretations). (shrink)