Politics Among Nations: The Struggle for Power and Peace

The six principles, added as an introductory chapter to the second edition, assert that politics is governed by objective laws rooted in human nature; that the key concept is interest defined as power; that interest is not fixed but varies with context; that universal moral principles cannot be applied to state actions without regard for time and place; that the moral aspirations of a particular nation cannot be equated with universal morality; and that the political sphere maintains its own autonomous standards distinct from economics, law, or ethics.

Morgenthau rejected the interwar idealist assumption that international law, collective security, and world opinion could reliably prevent war. He argued that these mechanisms were weak because they ignored the underlying struggle for power. His realism insisted that states must prioritize the rational pursuit of national interest defined as power, not moral or ideological aspirations. This did not mean amorality: Morgenthau acknowledged that moral principles influence statecraft, but they must be filtered through the concrete circumstances of time and place.

Morgenthau treated the balance of power as the primary mechanism for restraining the struggle for power and preserving peace. However, he was not naive about it: he warned that nations cannot reliably calculate power distributions, so they must seek a 'margin of safety'—superiority rather than strict equality—to avoid disadvantage. He also argued that the postwar bipolar system was far less stable than earlier multiple balances because of inflexibility, the disappearance of the balancer, and the rigidity of the two-bloc system.

Waltz's 1979 Theory of International Politics overtook Morgenthau's text in the classroom by shifting the explanation for state behavior from human nature to the structure of the international system. Where Morgenthau rooted the struggle for power in a universal 'lust for power,' Waltz argued that anarchy itself forces states to seek security and power regardless of human nature. This structural turn made neorealism appear more parsimonious and 'scientific,' while relegating Morgenthau's classical realism to a more historical and philosophical tradition.

No—this is a common misreading. Morgenthau insisted that moral principles are real and relevant, but that universal morality cannot be applied directly to state actions without considering consequences. He distinguished between a statesman's 'official duty' to protect national interest and his 'personal wish' to see universal moral values realized. The sixth principle on the autonomy of politics sat uneasily alongside his acknowledgment of moral significance, but he consistently argued that prudence, not moral crusading, should guide foreign policy.

Politics Among Nations remains one of the most widely known texts in international relations, entering its seventh edition in 2005. Interest revived after the Iraq war, which many saw as a repudiation of Morgenthau's prudence in favor of neoconservative moralism. However, critics note its dated examples, its near-exclusive focus on military and diplomatic power, and its neglect of economic factors, propaganda, and domestic policy-making. Its defense of diplomacy as the path to peace still resonates, though few scholars today accept its full anthropological pessimism.