Descartes, René (1596-1650)

Objections and Replies

Paris

Michel de Soly

1641

Gravity is coexistence with a heavy body in the same way that the mind is coextensive with the body

For example, I conceived of gravity as if it were some sort of real quality, which inhered in solid bodies; and although I called it a 'quality', thereby referring it to the bodies in which it inhered, by adding that it was 'real' I was in fact thinking that it was a substance. In the same way clothing, regarded in itself, is a substance, even though when referred to the man who wears it, it is a quality. Or again, the mind, even though it is in fact a substance, can nonetheless be said to be a quality of the body to which it is joined. And although I imagined gravity to be scattered throughout the whole body that is heavy, I still did not attribute to it the extension which constitutes the nature of a body. For the true extension of a body is such as to exclude any interpenetration of the parts, whereas I thought that there was the same amount of gravity in a ten foot piece of wood as in one foot lump of gold or other metal - indeed I thought that the whole of the gravity could be contracted to a mathematical point. Moreover, I saw that the gravity, while remaining coextensive with the heavy body, could exercise all its force in any one part of the body; for if the body were hung from a rope attached to any part of it, it would still pull the rope down with all its force, just as if all the gravity existed in the part actually touching the rope instead of being scattered through the remaining parts. This is exactly the way in which I now understand the mind to be coextensive with the body - the whole mind in the whole body and the whole mind in any one of its parts. But what makes it especially clear that my idea of gravity was taken largely from the idea I had of the mind is the fact that I thought that gravity carried bodies towards the centre of the earth as if it had some knowledge of the centre within itself. For this surely could not happen without knowledge, and there can be no knowledge except in a mind. Nevertheless I continued to apply to gravity various other attributes which cannot be understood to apply to a mind in this way - for example its being divisible, measurable and so on.
(Sixth Set of Replies, p. 297-8)

Physics::Gravity

Past Masters

Descartes, René. The Philosophical Writings of Descartes. Trans. John Cottingham, Robert Stoothof, and Dugald Murdoch. Cambridge: Cambridge University Press, 1985.

10/07/2003

10/23/2003