ABSTRACT
We have previously1 discussed at some length Newton's arguments that matter in no way entails an 'active principle' and that motion cannot be accounted for from matter alone, indeed that without some active principle the motion of matter must inevitably cease. Newton was by no means alone in seeing this; it was recognized by most of the leading thinkers of the seventeenth century, such as Descartes, Gassendi, and the Occasionalists. Newton's arguments are of special importance because of his insistence that the 'active principle' must be operative within the scheme of nature and not ex machina as in the case of Descartes, Gassendi, and the Occasionalists. In regard to this last point, we have seen2 that Leibniz concurred with Newton on the necessity of the active principle being within nature but maintained that Newton's doctrine also involved the deus ex machina fallacy. Leibniz's arguments respecting how the active principle is to be conceived as within nature are of singular significance and must be considered in some detail.
