Leibniz's criticism of occasionalism and a response through a reconstruction of al-Ghazālī's and Malebranche's arguments

Occasionalism is a theory of causation in which it is argued that God is the only causal agent and the cause effect relations perceived in nature are actually occasional causes or customary conjunctions determined by divine volition (Muhtaroğlu, 2017a, p. ix). Leibniz became familiar with occasionalism through Malebranche's elaboration. He found the occasionalist thesis problematic because created substances lack causal powers in the occasionalist theory, which according to him meant therefore that the theory is bound to turn into monism. For Leibniz, if substances lack an intrinsic force to act, then their substantiality cannot be accounted for (Leibniz, 1989, p. 159-60). This makes "God the very nature of things, while created things disappear into mere modifications of the one divine substance" (Leibniz, 1989, p. 165). To what extent does this criticism undermine occasionalism? Is it possible to argue for substances while rejecting any forces intrinsic to the natures of things? In this thesis, I will answer these questions by using the arguments and metaphysical frameworks of two occasionalists from two distinct traditions; al-Ghazālī from the Ashʿarite school and Malebranche from the Cartesian occasionalists. After elaborating Leibniz's criticism, I expound on the motivations and the arguments for occasionalism and the ontological frameworks of the thinkers respectively. My thesis shows that the respective frameworks of al-Ghazālī and Malebranche give them sufficient tools to argue against natures or forces intrinsic to creatures while arguing for the existence of created substances and hence, Leibniz's criticism is shown to be begging the question.