 The Neo-Kantians did not always think of themselves as members of a common movement. Though the members of the Marburg school very clearly identified with one another, and the members of the Southwest school identified themselves with one another, the two schools  initially[4]  made little effort to present themselves as part of a common movement. Their doctrines were different in some fundamental ways, and they often criticized one another’s positions. Nevertheless, there were some common features of Neo-Kantians of both schools—common features that made it natural for their contemporaries and for historians today to talk about them together. This section presents seven common features of the Neo-Kantians. These seven common features make it possible to distinguish, in a principled philosophical way, between the (“classical”) Neo-Kantians of the Marburg and Southwest schools and the various “back to Kant” philosophers of the mid nineteenth century and the assorted philosophers contemporary with the Neo-Kantians who were “neo-Kantian” in some broader sense. For example, Helmholtz and Lange did not share the Neo-Kantians’ anti-psychologism or commitment to the transcendental method (features 2 and 3 below), while Alois Riehl did not share their idealistic theory of objective validity (feature 6).