Think: A Compelling Introduction to Philosophy

by Simon Blackburn

When we do use our intellects, abstracting away from the data of the senses, what kind of world are we left with? Descartes, the mathematician, believed that the real property of ‘res extensa’ was, as the name suggests, spatial extension. Everything else was the possibly illusory, sensory ‘filling’ of spatial volume by things like colours and feels—things that, like Galileo, he believed to have their real residence only in the mind. So as well as opening up dualism of mind and body Descartes and his contemporaries open up a dualism between the world as it is for us (sometimes called the ‘manifest image’)—the coloured, warm, smelly, noisy, comfortable, familiar world—and the world as it is objectively or absolutely (the ‘scientific image’)—the world that contains nothing but physical particles and forces spread out across the boundless spaces of the cosmos.