Gandhi's advice to the young man that he should still practise absolute non-violence if someone attacked his sister, is not perfect. He would better have advised the use of force unless the young man were so developed that he could successfully defend her without it and unless the assailant were so sensitive that non-violence would bring out a response in him. In other words, the pacifist principle should certainly be applied in every case where it is likely to be effective but refrained from where it is likely to fail. It is not a principle of universal applicability.
-- Notebooks Category 11: The Negatives > Chapter 3: Their Presence in The World > # 439