על סיווג הכוח ועל ממשות התנועה בפילוסופיה של לייבניץ

Using the idea of phenomena bene fundata, Leibniz expresses a kind of relationship between the fundamental level of reality and physical phenomena. This expression signifies the fact that although physical phenomena do not belong to the fundamental level of metaphysical reality, they are not to be considered an illusion. Such phenomena are real in a certain sense due to the source from which they emanate. But what is that limited sense of reality and how is it established? This question, which is usually formulated in relation to the reality of matter and bodies, is discussed in this paper in the context of the phenomenon of motion. The main issue of interest is the sense in which the motion of a body from one place to another, despite it being only a phenomenon, is still something real. The effort to provide a solid foundation for the phenomenon of motion and to furnish it with a certain degree of reality lies at the heart of Leibniz' science of dynamics and reflects its role in creating a bridge between metaphysical and physical reality. This effort is important in several contexts. First, it expresses Leibniz' opposition to the geometrization of nature and in particular the idea that motion does not go beyond its geometric traits. Leibniz' attempt to provide a solid foundation for the phenomenon of motion also becomes crucial in light of the fact that he adopts a relational view of space, arguing that from the viewpoint of its relativity, motion does not really exist. Against this background, the need to defend the reality of motion and thereby to ensure the existence of change becomes an urgent task for Leibniz, who is interested in preserving the Aristotelian principle of activity in nature. Leibniz lays the foundation for the existence of real and absolute motion by means of his concept of force. In this paper, I present the meticulous classification that he outlines between various types of force and consider the manner in which it helps to rescue motion from its relativity. Particularly important in this context is the modification of a primitive and metaphysical type of force and its embodiment in the physical forces that are involved in actual motion. I consider the modification of force from two different interpretative angles (the idealistic and the realistic) and conclude with the important role of what Leibniz calls dead force (vis mortua) in providing a solid foundation for the phenomenon of motion.