 Friedman speaks of these as “historically contingent but constitutive a prioris”. His 2011 takes first steps beyond the two-process dynamic of his 2001 to address the problem of changing conceptions of rationality (i.e., intersubjective objectivity) and to bring in a wider social dimension. Like Renn, Friedman makes philosophical reflection a key to understanding changes so rapid that they amount to discontinuities. Up to a point he defends Kuhn on the existence of scientific revolutions and incommensurability. Kuhn ran into trouble with incommensurability and relativism, he says, for failing to include the history of scientific philosophical reflection that parallels the first-order, technical scientific work itself. Friedman’s leading example is also the relativity revolution.