“I agree with everything you say, but I would attack to the death your right to say it.”
Source: Lord Malquist and Mr Moon (1966), Ch. 2: A Couple of Deaths and Exits.
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Tom Stoppard 116
British playwright 1937Related quotes
“I disapprove of what you say, but I will defend to the death your right to say it,”
Source: The Friends of Voltaire (1906), Ch. 7 : Helvetius : The Contradiction, p. 199; because of quote marks around the original publication of these words, they are often attributed to Voltaire, though Hall was not actually quoting him but summarizing his attitude with the expression. The statement was widely popularized when misattributed to Voltaire as a "Quotable Quote" in Reader's Digest (June 1934), but in response to the misattribution, Hall had been quoted in Saturday Review (11 May 1935), p. 13, as stating: I did not mean to imply that Voltaire used these words verbatim and should be surprised if they are found in any of his works. They are rather a paraphrase of Voltaire's words in the Essay on Tolerance — "Think for yourselves and let others enjoy the privilege to do so too."
The paragraph in which the statement first appears reads:
Context: 'What a fuss about an omelette!' he had exclaimed when he heard of the burning. How abominably unjust to persecute a man for such an airy trifle as that! "I disapprove of what you say, but I will defend to the death your right to say it," was his attitude now.

“I disapprove of what you say, but I will defend to the death your right to say it.”
Variants:
Monsieur l’abbé, I detest what you write, but I would give my life to make it possible for you to continue to write.
I wholly disapprove of what you say—and will defend to the death your right to say it.
Though these words are regularly attributed to Voltaire, they were first used by Evelyn Beatrice Hall, writing under the pseudonym of Stephen G Tallentyre in The Friends of Voltaire (1906), as a summation of Voltaire's beliefs on freedom of thought and expression. http://books.google.it/books?id=j3kGAQAAIAAJ&q=%22I+disapprove+of+what+you+say,+but+I+will+defend+to+the+death+your+right+to+say+it%22+intitle:%22The+Friends+of+Voltaire%22&dq=%22I+disapprove+of+what+you+say,+but+I+will+defend+to+the+death+your+right+to+say+it%22+intitle:%22The+Friends+of+Voltaire%22&hl=it&ei=6J3uTbDYKcLX8gOnkLGTBw&sa=X&oi=book_result&ct=result&resnum=1&ved=0CCsQ6AEwAA
Another possible source for the quote was proposed by Norbert Guterman, editor of "A Book of French Quotations," who noted a letter to M. le Riche (6 February 1770) in which Voltaire is quoted as saying: "Monsieur l'abbé, I detest what you write, but I would give my life to make it possible for you to continue to write" ("Monsieur l'abbé, je déteste ce que vous écrivez, mais je donnerai ma vie pour que vous puissiez continuer à écrire"). This remark, however, does not appear in the letter.
Misattributed

“I don't necessarily agree with everything that I say.”

Speech to the Hawarden Amateur Horticultural Society (17 August 1876), as quoted in "Mr. Gladstone On Cottage Gardening", The Times (18 August 1876), p. 9
1870s
Context: I am delighted to see how many young boys and girls have come forward to obtain honourable marks of recognition on this occasion, — if any effectual good is to be done to them, it must be done by teaching and encouraging them and helping them to help themselves. All the people who pretend to take your own concerns out of your own hands and to do everything for you, I won't say they are imposters; I won't even say they are quacks; but I do say they are mistaken people. The only sound, healthy description of countenancing and assisting these institutions is that which teaches independence and self-exertion... When I say you should help yourselves — and I would encourage every man in every rank of life to rely upon self-help more than on assistance to be got from his neigbours — there is One who helps us all, and without whose help every effort of ours is in vain; and there is nothing that should tend more, and there is nothing that should tend more to make us see the beneficence of God Almighty than to see the beauty as well as the usefulness of these flowers, these plants, and these fruits which He causes the earth to bring forth for our comfort and advantage.

Helen Schucman (1976), in interview by David Hammond August 1976 in Belvedere, California. Republished in: " An interview with Helen Schucman http://merelyacim.wikispaces.com/An+interview+with+Helen+Schucman" at merelyacim.wikispaces.com. Accessed May 21, 2014.

Quoted in "Govt behind Ballali death? I`ll resign..." http://ippmedia.com/ipp/guardian/2008/05/26/115168.html The Guardian (2008-05-26)

Quoted in Richard Ellman A Long the Riverrun: Selected Essays (1988), p. 253