There is a temptation to use the term ‘science’ indiscriminately to stand for any legitimate enquiry. Inevitably it is a matter of dispute whether Descartes’ proposed new method and discipline should be regarded as philosophy at all. Interestingly Descartes does draw in the Rules a distinction between two kinds of question, namely those that are ‘perfectly understood’ and those that are ‘imperfectly understood’. The Cartesian picture strictly draws no sharp line of demarcation between science and philosophy. By contrast the Kantian picture at least indicates one such frontier, in which to move from science to philosophy is to move from answerable questions to those which are in various ways confused, empty, and unanswerable. The number of mistakes and ambiguities in the quoted accounts suggests that the doctrine behind them had become too deeply embedded in the revolution to be seriously scrutinised.