In a very interesting article, “‘A History of Problems,’” Elie During makes several important claims about the relation between Bergson and the French epistemological tradition, represented most particularly by Bachelard and Canguilhem. An anti-positivist account of concepts, by contrast, gives priority not only to concepts over facts but even more fundamentally to the problems which are the points of departure for concept formation and scientific research more generally. In short, then, in so far as the truth or falsity of problems is evaluated with reference to the intuitive, contentful grasp of duration, Bergson’s conception of problems retains a positivist element. Canguilhem, like Bergson and Bachelard, claims that there is a tight connection between the formation of scientific concepts and problems. Problems for Deleuze are rather responsible for the genesis of the thinking subject. This is the first sense in which problems, for Deleuze, are objectively real.