A Note on Leibniz's Supposed Flirtation with Occasionalism in the 1669 Letter to Thomasius

Abstract

In his article Leibniz: Physics and Philosophy, Daniel Garber asserts that the early Leibniz was mechanist and believed that only God has the ability to move by continually recreating them in different places..... Garber believes that these views, which Leibniz explicitly holds in the 1669 letter to Thomasius, support his claim that Leibniz accepted version of occasionalism in that letter. Garber's case is strong one, for the letter to Thomas ius develops ideas that are quite suggest ive of occasionalism. Nonetheless, this paper argues that Leibniz does not hold an occasionalistic notion of causation in the 1669 letter to Thomasius. Garber mistakenly ascribes occasionalism to the early Leibniz because he interprets Leibniz's views within Cartesian framework. Only by understanding how Leibniz's Aristotelian concept of substance in the 1669 letter to Thomasius leads to metaphysics quite distinct from Cartesianism 3 will it be clear why the ideas developed in that letter do not amount to occasionalism. Leibniz makes at least four claims in the letter to Thomasius that are remarkably similar to claims made by Descartes. First, Leibniz accepts the signature feature of mechanical philosophy that only magnitude, figure, and motion are to be used in explaining corporeal properties . Second, Leibniz rejects the scholastic notion of substantial forms in which a kind of immaterial being, though insensible in bodies...spontaneously imparts motion to body...without the help of an external thing . Third, matter cannot cause motion in itself, nor can motion arise out of matter spontaneously (i.e., without an external cause). Leibniz argues that because we can assume nothing in which does not follow from the definition of extension and antitypy [the attributes of matter,]...there is no motion, strictly speaking, as real entity in bodies . Finally, motion is explained by God's constantly creating things ex nihilo .