# Hans Morgenthau German-born American political scientist (1904–1980) — the founder of **classical realism** in international relations and, for a generation, the most influential American thinker on foreign policy. His textbook *Politics Among Nations* (1948) defined the field's terms and trained the Cold War foreign-policy establishment. ## *Politics Among Nations* and the six principles A Jewish émigré who fled Nazi Germany and settled at the **University of Chicago**, Morgenthau wrote *Politics Among Nations: The Struggle for Power and Peace* (1948) as a frontal assault on the **legalistic-moralistic** approach to foreign affairs he blamed for the catastrophe of the interwar years. Against the liberal faith that law, treaties, and international institutions could tame conflict, he argued that international politics is a perennial **struggle for power** among states pursuing their interests. His **six principles of political realism** distilled the view: politics is governed by objective laws rooted in human nature; the signpost of realism is **"interest defined in terms of power"**; interest is universal but its content is historically contingent; universal moral principles cannot be applied to state action in the abstract; no nation's morality is identical with the moral laws governing the universe; and the political sphere is autonomous, not reducible to economics, law, or ethics. ## Realism with a conscience Morgenthau's realism was not amoral. He insisted that the statesman must weigh consequences and exercise prudence — the cardinal political virtue — rather than pursue ideological purity. From that same realist premise he became, in the 1960s, a prominent **critic of the Vietnam War**, breaking publicly with the Johnson administration and arguing that the war served no defensible American national interest. The break cost him his advisory role and demonstrated that realism, properly applied, could be a brake on intervention rather than a license for it. ## KB Significance Morgenthau is the **theorist who gave American realism its grammar**. Where [[George Kennan]] practiced realism in policy, Morgenthau systematized it into a teachable theory; where [[Kenneth Waltz]] would later strip it down to cold structure, Morgenthau kept human nature and statecraft at the center. For this KB he is the anchor of the [[Realism (International Relations)]] tradition — the intellectual lineage that runs to [[Henry Kissinger]] and that today underwrites the foreign-policy realism increasingly audible on the right, which frames restraint and great-power balancing as the genuinely conservative alternative to neoconservative crusading. ## See Also - [[Realism (International Relations)]] — the paradigm he founded. - [[Kenneth Waltz]] — who recast realism as structural theory. - [[George Kennan]] · [[Balance of Power]] · [[International Relations]]