It is difficult to evaluate the role of activity - of force or of that which has causal efficacy - in Descartes’ natural philosophy. On the one hand, Descartes claims to include in his natural philosophy only that which can be described geometrically, which amounts to matter (extended substance) in motion (where this motion is described kinematically).’ Yet on the other hand, rigorous adherence to a purely geometrical description of matter in motion would make it difficult to account for the (...) interactions among the particles that constitute Descartes’ universe, since the notions of extension and kinematical motion do not in themselves imply any causal agency. There is, after all, no reason to expect that a particle whose single essence is extension, even if we suppose it to be moving, should impart motion to another particle, while conversely, there is no reason to expect a resting particle to hinder the motion of an impinging one. Descartes' hankering for an austere ontology of matter in motion is in danger of excluding causal agency (force, conceived dynmically) from matter. To the modern reader it may seem obvious that Descartes did not get himself into such a fix, since matter in motion so readily reminds us of kinetic energy or of some more primitive notion of force. Yet by no means is it obvious that Descartes attributed causal efficacy to matter in motion per se. Serious scholars have held opposite positions on this issue. Westfall, Gabbey, and others’ have argued that although on the metaphysical plane Descartes attempted to eliminate force from his mechanical universe, nonetheless ‘force is a real feature’ of his mechanical world. The thrust of this view is that Descartes conceived of force as ‘the capacity of a body in motion to act’, by means of impact, upon other bodies. An opposing interpretation, defended here, is that Descartes did in fact deny causal agency to moving matter per se, restricting agency to immaterial substances such as the human mind, angels, and God. The intention of this interpretation is not to de-emphasize the role of matter in motion in Descartes’ explanation of nature, but rather to stress the fact that Descartes did not conceive of this moving matter dynamically. -/- Reprinted in Descartes, ed. by J. Cottingham, Oxford Readings in Philosophy (Oxford: Oxford University Press, 1998), 281–310. (shrink)

Spinoza ' s understanding and understanding Spinoza -- Spinoza ' s understanding -- Understanding Spinoza -- The metaphysics of substance -- Descartes and substance -- Spinoza contra Descartes on substance -- Modes -- Necessitarianism -- The purpose of it all -- The human mind -- Parallelism and representation -- Essence and representation -- Parallelism and mind - body identity -- The idea of the human body -- The pancreas problem, the pan problem, and panpsychism -- Nothing but representation -- Representation, (...) will, and belief -- Skepticism -- Psychology : striving and self - preservation -- Conatus -- Desire, joy, and sadness -- Love, hate, and all that -- The ethics of the ethics -- The good notion of the good -- The right notion of the right -- Knowledge and morality -- Freedom and morality -- Helping others -- Lies and degrees of freedom -- The state, religion, and scripture -- Rights and power -- Religion and the state -- Scripture -- Prophecy and the truth of the Bible -- From PSR to eternity -- The aftermath of Spinoza -- Leibniz -- Bayle and Hume -- The pantheism controversy -- Hegel -- Nietzsche -- Prospects of spinozistic rationalism. (shrink)