Let me begin by making explicit some background assumptions so as to prevent some false impressions. I wish to avoid the impression of an overall dismissal of philosophy or even of contemporary philosophy. This is too easy to do by the observation that for ever so many purposes philosophy is useless; this is true of every field of human activity. I remember full well how distasteful I found Hilary Putnam's declaration, during the turbulent days of the student revolt, when we sat on a panel together in Boston University: all the philosophy we teach, he declared, is just bourgeois crap. I do not agree. We teach the history of philosophy, and the history of theories about science, including the views of Bacon and Descartes and of Whewell and of Duhem and Poincaré, and these are neither bourgeois nor crap. I am speaking in the present essay of the political significance of the contemporary scene, not of philosophy in general, nor of the philosophy of science in general nor of significance in general.