 However, Reichenbach’s first monograph on relativity (1920) was written from within a neo-Kantian perspective. As Friedman (1994) and others (Ryckman 2005) have discussed in detail Reichenbach’s innovation, a modification of the Kantian conception of synthetic a priori principles, rejecting the sense of “valid for all time” while retaining that of “constitutive of the object (of knowledge)”, led to the conception of a theory-specific “relativized a priori”. According to Reichenbach, any physical theory presupposes the validity of systems of certain, quite general, principles which however may vary from theory to theory. These coordinating principles, as they are then termed, are indispensable for the ordering of perceptual data; they define the objects of knowledge within the theory. The epistemological significance of relativity theory, according to the early Reichenbach, is to have shown, contrary to Kant, that these systems may contain mutually inconsistent principles, and so require emendation to remove contradictions. Thus a “relativization” of the Kantian conception of synthetic a priori principles is the direct epistemological result of the theory of relativity. But this finding is also taken to signal a transformation in the method of epistemological investigation of science. In place of Kant’s “analysis of Reason”, “the method of analysis of science” (der wissenschaftsanalytische Methode) is proposed as “the only way that affords us an understanding of the contribution of our reason to knowledge” (1920: 71 [1965: 74]). The method’s raison d’être is to sharply distinguish between the subjective role of (coordinating) principles—“the contribution of Reason”—and the contribution of objective reality, represented by theory-specific empirical laws and regularities (“axioms of connection”) which in some sense have been “constituted” by the former. Relativity theory itself is a shining exemplar of this method for it has shown that the metric of spacetime describes an “objective property” of the world, once the subjective freedom to make coordinate transformations (the coordinating principle of general covariance) is recognized (1920: 86–7 [1965: 90]). The thesis of metric conventionalism had yet to appear.