Descartes on the Road to Elea: Essence and Formal Causation in Cartesian Physics and CorporealMetaphysics

This is a study of formal causation in the thought of René Descartes. It begins by sketching the internal complexity of formal causation as an explanatory notion in Aristotle and two of his most influential Christian admirers, St. Thomas Aquinas and Francisco Suárez. It is then argued that Descartes accepts what Suárez terms metaphysical formal causal explanations from essence while rejecting the formal causal explanations that are parasitic on Aristotelian hylomorphism. The textual basis for this interpretation relies heavily on a close reading of the Cartesian ontological argument for the existence of God and the associated understanding of God as causa sui. It is then argued that metaphysical formal causal explanations are also relevant within Cartesian physics and corporeal metaphysics. Particular attention is paid to the causality of the laws of motion, the impenetrability or solidity of matter, condensation and rarefaction, and the Cartesian rejection of idealism. The work concludes by showing how Descartes incurs an explanatory debt by rejecting the formal causal explanations characteristic of hylomorphism that he is unable to pay. The problem is that Descartes equates formal causation with metaphysical formal causation from essence, but this means formal causation can no longer explain the unity of the individual bodies that form the ontological bedrock of his physics. Since Cartesian metaphysics furnishes no alternative means of performing this explanatory work, Cartesian metaphysics implies an attenuated Eleaticism within the corporeal domain.