 There are four key ideas that are common to the Southwest and Marburg theories of objective validity. First, both schools emphasized the centrality of judgments (as opposed to concepts or intuitions), as the kind of representation that first makes objective validity possible (Rickert 1915: Ch.3; Cohen 1902: §10–11). Second, the Neo-Kantians were emphatic that the objective validity of knowledge does not consist in its being a copy (Abbild) or mirror of the object (Windelband 1910; Rickert 1934; Cassirer 1910: Ch.1; Rickert 1915: Ch.2). This “copy theory” of knowledge is inconsistent with a third key idea, that the objective validity of every area of culture is made possible by substantive a priori principles. The a priori principles that make possible some part of human culture are again not interpreted psychologistically: they are not features of the minds of individual subjects, they are not discovered empirically, and their necessity is not grounded in the empirical fact that they are universally accepted. These a priori principles are parts of culture—they are its fundamental norms or laws. Fourth, the Neo-Kantians described themselves as “idealists”. Idealism meant different things to different Neo-Kantians (see  section 2.2  and  3.2).  But all Neo-Kantians shared the view that knowledge requires a priori elements that are not present in what is given in immediate intuition. Knowledge, then, requires a “reshaping” or “transformation” of what is given. The copy theory that they reject would in this sense be a kind of “realism”. Of course, Neo-Kantian idealism must be rigorously distinguished from other kinds of idealisms. As noted earlier, they reject Kant’s doctrine of the thing-in-itself, and they emphatically do not believe that objects are in any way subjective or dependent on the representations of individual psychological subjects.