We do not protect freedom in order to indulge error. We protect freedom in order to discover truth. We do not maintain freedom in order to permit eccentricity to flourish; we maintain freedom in order that society may profit from criticism, even eccentric criticism. We do not encourage dissent for sentimental reasons; we encourage dissent because we cannot live without it.

Henry Steele Commager (1902–1998) American historian, writer, activist

Essay (1951), “The Pragmatic Necessity of Freedom”
    (Source)

This was originally given as a Cooper Lecture, Swarthmore College (1951), collected as an essay in Clair Wilcox, ed., Civil Liberties Under Attack (1951).

Subsequently, it was given as a lecture at Cornell University (1953-10), before the revised version was included in Commager's Freedom, Loyalty, Dissent (1954) as "The Necessity of Freedom."