This is a quote from the book "The Virtue Of Selfishness" by Ayn Rand
...t is rationally appropriate to do so.
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This last means that one need not launch into unprovoked moral denunciations or debates, but that one must speak up in situations where silenc
e can objectively be taken to mean agreement with or sanction of evil. When one deals with irrational persons, where argument is futile, a mere “I don’t agree with you” is sufficient to ne
gate any implication of moral sanction. When one deals with better people, a full statement of one’s views may be morally required. But in no case and in no situation may one permit one’s ow...