… is from page 3 of Bryan Caplan’s deeply insightful and informative 2007 book, The Myth of the Rational Voter (original emphasis):
In the minds of many, one of Winston Churchill’s most famous aphorisms cuts the conversation short: “Democracy is the worst form of government, except all those other forms that have been tried from time to time.” But this saying overlooks the fact that the governments vary in scope as well as form. In democracies the main alternative to majority rule is not dictatorship, but markets.
