The phrase "I may disagree with what you say, but I will defend to the death your right to say it" is commonly attributed to the French philosopher Voltaire. However, it was actually written by Evelyn Beatrice Hall in 1906 as a summary of Voltaire's beliefs on free speech, not a direct quote from him. Hall wrote it in her book "The Friends of Voltaire" to illustrate Voltaire's attitude toward freedom of expression. Voltaire himself advocated for free speech but likely never spoke or wrote this exact phrase.