Philosophers regularly debate with their predecessors, historians of philosophy are often astonished at the results, yet the two seldom exchange notes. The Bounds of Sense, published in 1966 by Peter Strawson, is one of the best books by one of the finest Oxford philosophers of our day: an interpretation of Kant’s Critique of Pure Reason, the author allows in the second sentence of the preface that, ‘as any Kantian scholar who may read it will quickly detect, it is by no means a work of historical-philosophical scholarship’. In the other philosophical tradition, Martin Heidegger brought out a study of Kant in 1929 which immediately sold out: in his preface to the second edition (1950), he allowed that the ‘violence’ of his interpretation, deplored by Kantian scholars, could indeed be substantiated from the text, but fended off the criticism by claiming that ‘historical-philosophical research is always justified when it makes this objection against attempts that want to bring about a thoughtful conversation between thinkers’. He goes on: ‘In contrast to the methods of historical philology, which has its own task, a thoughtful dialogue stands under different laws’. In short, students of the history of philosophy have a job to do; but they have no part in the conversation in which philosophical thought takes place. Heidegger, and even Strawson, clearly regard the work of historians of philosophy as less than vital for the advance of philosophy.

University students of philosophy, in whichever tradition, learn within their first few weeks to rehearse the objections to Cartesianism; it is not an objection that, historically, Descartes may never have been a Cartesian.