Mansfield’s conclusion is a spirited attack on the idea of homo economicus:“
“The economists I know are generally, as individuals, sober and cautious, the most respectable of all professors and in their honesty and reliability representing the best in bourgeois virtue. But when they get together as economists, they give way to boyish irrational exuberance over the accomplishments and prospects of economics as a science.”
“it is not possible for us, or most of us, to live perfectly flexibly, always ready to calculate anew in fresh circumstances what it is in our interest to do. Thus the ideal of calculated self-interest posited by economics is not a human possibility. We will get in the habit of being spenders or savers and will not be able to turn on a dime, changing our behavior when our interest changes. Indeed our selves are not independent of our ways of life, and it is not possible to calculate your self-interest without knowing your way of life.
Economics needs to stop trying to duck responsibility for what it recommends. It needs to examine the whole of life and to focus on the virtue or virtues of different ways of life. It should give over talk about "preferences," as if human desires were given facts unaffected by the science of economics. It should abandon the crude positivism that claims that one can study facts without giving advice, or that one can confidently predict without causing people to believe in one's predictions. It needs to replace its false modesty with true moderation.” The failure of the predictions of so many economists should remind us that economics is a social science not a pure science. Indeed, one of the reasons why behavioural economics is so valuable is that it reminds us of this crucial point.