… is from pages 168-169 of Gordon Tullock’s 1983 essay “The Machiavellians and the Well-Intentioned,” which is reprinted in The Economics and Politics of Wealth Redistribution  (volume 7 of The Selected Works of Gordon Tullock, Charles K. Rowley, ed. ):
Most of us like to think of ourselves as helping the poor and doing other good things, and we like also to have our own income and real well-being improved. The politician who argues that you should do something which will benefit you, not because it will benefit you but because it is abstractly the good and just, gets more votes than the politician who points out the difficulties with that line of reasoning. All of us like to think that we are better, more altruistic, more charitable, than we actually are. But, although we have this desire, we don’t want to pay for it. We are willing to make a sacrifice of perhaps 5 percent of our real income in charitable aid to others. We would like to think of ourselves, however, as making much larger transfers without actually making them. One of the functions of the politician in our society is to meet this demand – the demand I suppose one can call a demand for hypocrisy but nevertheless a very human demand. He provides arguments that programs which benefit us personally are actually aimed at helping the poor, the national interest, a cure for cancer, etc.