A Little History of Philosophy (Little Histories)

by Nigel Warburton

Spinoza did not just admire geometry; he wrote philosophy as if it were geometry. The ‘proofs’ in his book Ethics look like geometrical proofs and include axioms and definitions. They are supposed to have the same relentless logic as geometry. But instead of dealing with topics like the angles of triangles and the circumferences of circles, they are about God, nature, freedom and emotion. He felt that these subjects could be analysed and reasoned about in just the same way that we can reason about triangles, circles and squares. He even ends sections with ‘QED’ which is short for quod erat demonstrandum, a Latin phrase meaning ‘which was to be proved’ that appears in geometry textbooks. There is, he believed, an underlying structural logic to the world and our place in it that reason can reveal. Nothing is as it is by chance, there is a purpose and principle to it all. Everything fits together in one huge system and the best way to understand this is by the power of thought. This approach to philosophy, emphasizing reason rather than experiment and observation, is often labelled Rationalism.