When my information changes, I alter my conclusions. What do you do, sir?

Reply to a criticism during the Great Depression of having changed his position on monetary policy, as quoted in "The Keynes Centenary" by Paul Samuelson, in The Economist Vol. 287 (June 1983), p. 19; later in The Collected Scientific Papers of Paul Samuelson, Volume 5 (1986), p. 275; also in Understanding Political Development: an Analytic Study (1987) by Myron Weiner, Samuel P. Huntington and Gabriel Abraham Almond, p. xxiv; this has also been paraphrased as "When the facts change, I change my mind. What do you do, sir?"