René Descartes is famous as the philosopher who was prepared to doubt everything- even his own physical existence. Most people also know that he said 'I think, therefore I am', even if they are not always sure what he really meant by it. Introducing Descartes explains what Descartes doubted, and why he is usually called the father of modern philosophy. It is a clear and accessible guide to all the puzzling questions he asked about human beings and their place in the world. Dave Robinson and Chris Garratt give a lucid account of Descartes' contributions to modern science, mathematics, and the philosophy of mind- and also reveal why he liked to do all of his serious thinking in bed.