This chapter deals with Marx as a philosopher, rather than, as an economist, an historian, a journalist. It is clear that Marx had the qualifications to be treated as a philosopher: it was in the field of philosophy that he earned his Doctorate, and his dissertation was adequate by the standards of the German universities of his student days. He had a temperament that naturally revelled in extended and complex inquiry. The practice of treating Marx as a philosopher may be challenged from two perspectives: from that of mainstream philosophy as it has been understood and taught in the universities in recent times and from that of orthodox Marxism as it has come to be regarded by many of those who today label themselves Marxists. At any rate, interest in Marx among professional teachers and students of philosophy strikes one as being greater now than at any time in the recent past.