A striking number of accounts stress the continuity between the foreign policy of Wilhelmine and Nazi Germany. Hitler was simply a more virulent nationalist and militarist, so some sort of revisionist expansion was inevitable in German foreign policy. The Nazis, however, were a fundamentally different type of right-wing force. Hitler dismissed the very existence of humanitarian ethics as a mere social construction and illusion, refusing even the typical scorn more traditional German nationalists expressed vis-à-vis its wartime adversaries. Hitler’s regime explicitly redefined the national community not as a cultural and linguistic entity but as a biological one. Rather than a continuation of previous tendencies in German nationalism, it was a decisive moral break and led to a wholly different basis for, and type of, international aggression. Hitler dismissed the ambitions of Weimar nationalists of the Wilhelmine variety, whose only interest was to rail against the injustices of the Versailles Treaty and demand the return of lost German lands that were rightly hers. For Hitler, no one had any right to any piece of territory; one simply took it. As a consequence, he defined fundamentally different foreign policy goals than his contemporaries and predecessors: the creation of Lebensraum to provide for Hitler’s growing population.

A comparison of the behavior of the German army in World War I and World War II in occupied Eastern Europe shows the human cost of the difference between Wilhelmine and Nazi nationalism. Hitler aimed not at the paternalistic civilizing of conquered peoples but rather the elimination, evacuation, and instrumentalization of non-Aryan populations. Yet the fact that Hitler is the exemplar of this kind of instrumental violence indicates the rarity of behavior thought to be so common in international relations models. This has great normative implications. As much as moral philosophy seeks to maintain a separation between the way the world is and the way that it should be, all normative arguments rest on (even if only implicitly) empirical claims about what is possible. We know by the empirical rarity of those who think like Hitler that he was mistaken about the amoral nature of man, and therefore that normative theorizing still has a place. Once we understood where Hitler’s crude struggle-based biological determinism went wrong, by failing to recognize what is uniquely about humans among other animals – their morality – biology buttresses rather than undermines liberal ethics. Morality is more than a social construction.