So, what's a nudge? A nudge is some small feature of the environment that attracts our attention and alters our behavior.

Retirement savings is probably behavioral economists' greatest success story. It is a prototypical behavioral-economics problem because saving for retirement is cognitively hard - figuring out how much to save - and requires self-control.

One simple step firms can take is make sure that people that are getting paid a lot of money, say more than a million or two, that a big chunk of that money is deferred. That's going to change the whole ballgame.

There are cases when I can make myself better off by restricting my future choices and commit myself to a specific course of action.

The money has to be deferred with what they call "clawback," which means they can get it back if I lose it all. So that guy making ten million a year selling credit default swaps, if we're going to keep five million of it in escrow for ten years, and with the right to go back and get it, if he starts losing money, then we're going to give people the right incentives not too take so much risk.

The assumption that everybody will figure out how much they have to save and then will just implement that plan is obviously preposterous.

Most economists, including me, agree that longevity insurance would make sense for a lot of people.