[H]e, who will not reason, is a bigot; he, who cannot, is a fool; and he, who dares not, is a slave.

The aphorism divides resistance to reasoning into three moral/intellectual failures: refusal (bigotry), incapacity (folly), and fear (slavery). Its force lies in treating rational inquiry not merely as a cognitive skill but as an ethical duty and a condition of freedom. “Will not” targets dogmatism—choosing belief over evidence; “cannot” points to ignorance or lack of training; “dares not” highlights social or political coercion, where people self-censor to avoid punishment or exclusion. The progression implies that the gravest threat is intimidation, because it turns potentially rational agents into subjects who surrender autonomy. The line is often invoked in defenses of free thought, education, and civil liberty.