The epidemic of world lawlessness is spreading. When an epidemic of physical disease starts to spread, the community approves and joins in a quarantine of the patients in order to protect the health of the community against the spread of the disease.

Franklin D. Roosevelt used this “epidemic” and “quarantine” analogy in the late 1930s as fascist aggression in Europe and Asia intensified and the United States debated whether to remain neutral. The language is closely associated with his effort to shift American opinion away from strict isolationism by framing international aggression as a contagious threat to global stability. In this setting, “quarantine” referred not to medical policy but to collective action—economic and diplomatic pressure by peaceable nations—aimed at isolating aggressor states to prevent wider war. The metaphor was meant to make foreign conflict feel immediate and communal, like a public-health emergency requiring coordinated prevention.

The quote argues that lawlessness among nations behaves like a contagious disease: if unchecked, it spreads from one outbreak to many. By invoking quarantine, Roosevelt suggests that neutrality and passivity are inadequate responses; responsible communities isolate the source of infection to protect everyone. The deeper claim is moral and strategic: aggression is not merely someone else’s problem but a systemic danger that erodes international norms and eventually threatens even distant bystanders. The metaphor also softens the leap from noninvolvement to action—“quarantine” implies restraint and prevention (sanctions, diplomatic isolation) rather than immediate military intervention, while still insisting on collective responsibility.