Today we know that World War II began not in 1939 or 1941 but in the 1920’s and 1930’s when those who should have known better persuaded themselves that they were not their brother’s keeper.

Humphrey argues that the origins of World War II lay less in the formal outbreak dates (1939 in Europe, 1941 for the United States) than in the preceding decades’ moral and political failures. By invoking the biblical phrase “Am I my brother’s keeper?” he frames isolationism, appeasement, and indifference to aggression and persecution as a refusal of collective responsibility. The line suggests that catastrophic wars are incubated when leaders and publics rationalize inaction in the face of mounting injustice. In Humphrey’s broader political idiom—internationalism and liberal moral responsibility—the quote functions as a warning: peace depends on early, shared vigilance and a willingness to defend others’ security and rights before crises become irreversible.