Wehler's work has been criticized. From the Right, Otto Pflanze claimed that Wehler's use of such terms as "Bonapartism", "social imperialism", "negative integration" and Sammlungspolitik ("the politics of rallying together") has gone beyond mere heuristic devices and instead become a form of historical fiction.  The German conservative historian Thomas Nipperdey has argued that Wehler presented German elites as more united than they were, focused too much on forces from above and not enough on forces from below in 19th-century German society, and presented too stark a contrast between the forces of order and stabilization versus the forces of democracy with no explanation for the relative stability of the Empire.  In Nipperdey's opinion, Wehler's work fails to explain how the Weimar Republic occurred, since, according to Wehler, prior to 1918 the forces of authoritarianism were so strong and those of democracy so weak.  In a 1975 book review of Wehler's Das Deutsche Kaiserreich , Nipperdey concluded that a proper history of the Imperial period could only be written by placing German history in a comparative European and trans-Atlantic perspective, which might allow for "our fixation on the struggle with our great-grandfathers" to end.