Hume: Philosophy in an Hour. Paul Strathern

disease-ridden human hot water bottles would in most cases have arrived at their condition after suffering the same fate as Agnes, victims of the hypocrisy so necessary to any upright society of closet masochists.)

      Hume went first to live in Reims but later moved to La Fleche, almost certainly because of its inspiring associations with Descartes, who had been educated there at the Jesuit college. Within three years Hume had finished A Treatise of Human Nature. He was later to disparage this work because of what he considered to be its youthful extravagances. But he did not disavow its philosophy, which contains almost all the original philosophical ideas for which he is today remembered. Bertrand Russell, in his History of Western Philosophy, is even of the view that this work contains the best parts of Hume’s philosophy. Some achievement for a man who was not yet thirty.

      In A Treatise of Human Nature Hume attempted to define the basic principles of human knowledge. How do we know anything for certain? And what exactly is it that we do know for certain? In trying to answer these questions he followed in the empiricist tradition, believing that all our knowledge is ultimately based on experience. In Hume’s view, experience consists of perceptions, of which there are two types. ‘Those perceptions which enter with most force and violence we may name impressions; and, under this name, I comprehend all our sensations, passions and emotions, as they make their first appearance in the soul. By ideas I mean the faint images of these in thinking and reasoning.’

      He explains: ‘Every simple idea has a simple impression, which resembles it.’ But we can also form complex ideas. These are derived from impressions, by way of simple ideas, but need not necessarily conform to an impression. For example, we can imagine a mermaid by combining our idea of a fish and our idea of a woman.