In recent years, the American consumer spent too much money. Bought too much house, took on too much debt and generally lived beyond his or her means. Free-spending ways helped cause the worst financial crisis since the Great Depression.

And now they’re going to have to do their part to end the crisis. How? By spending. Enough already with the saving that many Americans have suddenly begun doing. This very moment, Congress and President Obama are preparing to send them a tax rebate, to inspire them to stimulate the economy, to spend as if the future of the country depended on it.

John Maynard Keynes, the great 20thcentury economist, would have appreciated the apparent absurdity in these mixed messages. He coined a phrase,“the paradox of thrift,”to point out that what was rational for an individual during hard times - saving money - could be ruinous for an entire economy. Eventually, many of the savers may end up out of work because everyone else is saving, too. At his recent news conference, Mr.Obama was asked directly whether people should spend or save their rebate checks. He avoided the question.

Fortunately, though, it has an answer. The first part involves figuring out how to spend money now to save money later - which can lift the economy today and help individual households cope with their battered finances in the long run. The second part involves realizing that Keynes’s paradox isn’t ironclad. In a financial crisis, when banks may need capital as much as retailers or restaurants need business, many people can save without guilt.

Besides developing the most famous prescription for curing downturns, Keynes can also be considered the godfather of behavioral economics, as the columnist David Ignatius recently wrote. While other economists obsessed over statistical models that treated people as hyperrational automatons, Keynes wrote about“animal spirits. He helped explain how psychology shaped economics.

Psychology-tinged economics - that is, behavioral economics - has taken off over the last two decades, and one of its central findings is that most people do not do a good job of planning for the future. They aren’t nearly as nice to their“future self, as economists say, as to their“present self.

They eat just one more doughnut and put off exercising until tomorrow . They fail to set aside enough for retirement.

These habits end up causing a lot of trouble. But they also present an opportunity in a time like this. Most people could save themselves a good bit of money by giving proper respect to their future self. They could spend a little now and save a lot later.

I asked behavioral economists for some examples, and they helped me come up with a nice little list. Parents of young children can pay to join a large retail store that offers members discounts and make up their membership fee with just a few months of diaper purchases. Frequent book buyers who don’t mind screen reading can buy the new Kindle. It costs $359, but most new books then cost less than $10. Families who shop at rent-to-own stores can temporarily pare back and then buy furniture or electronics outright. People who do a lot of laser printing can purchase a printer that uses only a cent or two of ink per page. (Many use far, far more.)

In these cases - and, no doubt, many others - the initial investment tends to pay off quickly, sometimes in mere months. That’s why such spending is perfectly suited to the moment. It will keep people employed or create new jobs when the economy needs the help. But it will also shore up households’finances.

The one big caveat is that some people will feel that they can’t afford to lay out an extra $50 or $100 right now.

Millions of workers have already lost their jobs, and many others simply want to cut back. In December, households saved an average of 3.6 percent of their disposable income, up from about 1 percent in recent years.

In a normal recession, this new saving would have a lot more downside than upside, just as Keynes explained. But this recession is different. It has been caused by a financial crisis. If Americans don’t get their finances in better shape banks will remain afraid to lend, and the recession will linger.

Even more immediately, banks need to get their own finances in order.

Whenever this recession finally ends, our future selves are going to be facing some very big bills. They can use all the help we can give them.

DAVID LEONHARDT/ ECONOMIC SCENE