An Econ would not expect a gift on the day of the year in which she happened to get married, or be born. What difference do these arbitrary dates make? In fact, Econs would be perplexed by the idea of gifts. An Econ would know that cash is the best possible gift; it allows the recipient to buy whatever is optimal. But unless you are married to an economist, I don’t advise giving cash on your next anniversary. Come to think of it, even if your spouse is an economist, this is not a great idea.

Of course, most economists know that the people with whom they interact do not resemble Econs. In fact, in private moments, economists are often happy to admit that most of the people they know are clueless about economic matters. But for decades, this realization did not affect the way most economists did their work. They had a justification: markets. To defenders of economics orthodoxy, markets are thought to have magic powers.

There is a version of this magic market argument that I call the invisible hand wave. It goes something like this. “Yes, it is true that my spouse and my students and members of Congress don’t understand anything about economics, but when they have to interact with markets. ...” It is at this point that the hand waving comes in. Words and phrases such as high stakes, learning and arbitrage are thrown around to suggest some of the ways that markets can do their magic, but it is my claim that no one has ever finished making the argument with both hands remaining still.

Hand waving is required because there is nothing in the workings of markets that turns otherwise normal human beings into Econs. For example, if you choose the wrong career, select the wrong mortgage or fail to save for retirement, markets do not correct those failings. In fact, quite the opposite often happens. It is much easier to make money by catering to consumers’ biases than by trying to correct them.

Perhaps because of undue acceptance of invisible-hand-wave arguments, economists have been ignoring supposedly irrelevant factors, comforted by the knowledge that in markets these factors just wouldn’t matter. Alas, both the field of economics and society are much worse for it. Supposedly irrelevant factors, or SIFs, matter a lot, and if we economists recognize their importance, we can do our jobs better. Behavioral economics is, to a large extent, standard economics that has been modified to incorporate SIFs.