Chapter 18 — How Princes Should Keep Faith

Everyone admits how praiseworthy it is in a prince to keep faith and live with integrity. What experience shows, however, is that the princes who have done great things have held good faith of little account and have known how to manipulate men through craft. In the end, those princes have overcome those who planted themselves on honesty alone. There are two kinds of combat: by law, proper to men, and by force, proper to beasts. The first is often insufficient, so the second must be used. A prince must therefore know how to use both the man and the beast — and Machiavelli cites the ancient instruction that Achilles and other princes were given to the care of Chiron the centaur as an allegorical acknowledgment of this necessity.

The two animals the prince must imitate are the fox and the lion: the fox to recognise traps, the lion to frighten wolves. A prince who is only a lion does not see the snares laid for him; one who is only a fox has no defence against open attack. He must be both. The practical rule that follows is stated without softening: a prince should not keep faith when keeping faith goes against his interest, and when the reasons that made him give his word no longer apply. Two conditions justify this: it must be difficult to keep, and the reasons for giving the promise no longer hold. Machiavelli adds that the prince can always find a reason to break faith when he needs one.

The historical evidence is the chapter's most provocative element. Alexander VI, Machiavelli observes, never did anything but deceive men, never thought about anything else, and always found material with which to do it. No man was ever more effective in assurances, or affirmed things with stronger oaths, yet kept them less. His deceits always succeeded because he knew so well the simple-minded side of men. Ferdinand of Aragon's pious wars were always fought for territory — the religious legitimation was a tool, not a motivation. The chapter closes with the practical rule: let the prince appear merciful, faithful, humane, religious, upright — and be prepared, when necessity demands, to be the contrary. Men judge primarily by appearances. A prince who can manage appearances controls his reputation, and reputation is what keeps a prince safe.