“The liar is no whit better than the thief.”
Roosevelt argues that criticism loses moral legitimacy when it becomes false, making truthfulness a constraint on reform even when the target of criticism may deserve scrutiny.
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The Man with the Muck-Rake, April 14, 1906. Roosevelt is discussing public criticism, journalism and slander; the surrounding speech simultaneously calls for relentless exposure of genuine wrongdoing when the attack is truthful.