A recent article in “The New York Times” by Richard H. Thaler expresses a realistic view of the problems of mortgages on houses that are greater than the value of the house. The following excerpts of Thaler’s article should be considered in determining if it is worth continuing to rent a house from a mortgage company if you can’t afford the rent

Much has been said about the high rate of home foreclosures, but the most interesting question may be this: Why is mortgage default rate so low?

After all, millions of American homeowners are “underwater,” meaning that they owe more on their mortgage than their home is worth. In Nevada, nearly two-thirds of homeowners are in this category. Yet most of them are dutifully continuing to pay their mortgages, despite substantial financial incentives for walking away from them.

A family that financed the entire purchase of a $600,000 home in 2006 could now find itself still owing most of that mortgage, even though the home is now worth only $300,000. The family could rent a similar home for much less than its monthly mortgage payment, saving thousands of dollars a year and hundreds of thousands over a decade.

Some homeowners may keep paying because they think it’s immoral to default. This view has been reinforced by government officials like former Treasury Secretary Henry M. Paulson, Jr., who while in office said that anyone who walked away from a mortgage would be “simply a speculator – and one who is not honoring his obligation.” (The irony of a former investment banker denouncing speculation seems to have been lost on him.)

But does this really come down to a question of morality?

A provocative paper by Brent White, a law professor at the University of Arizona, makes the case that borrowers are actually suffering from a “norm asymmetry.” In other words, they think they are obligated to repay their loans even if it is in their financial interest to do so, while their lenders are free to do whatever maximizes profits. It’s as if borrowers are playing in a poker game in which they are the only ones who think bluffing is unethical.

That norm might have been appropriate when the lender was the local banker. More commonly these days, however, the loan was initiated by an aggressive mortgage broker who maximized his fees at the expense of the borrower’s costs, while debt was packaged and sold to investors who bought mortgage-backed securities high returns, using models that predicted possible default rates.

The morality argument is especially weak in a state like California or Arizona, where mortgages are so-called “non-recourse loans.” That means the mortgage is secured by the home itself; in a default, the lender has no claim on a borrower’s other possessions. Non-recourse mortgages may be viewed as financial transactions in which the borrower has the explicit option of giving the lender the keys to the house and walking away. Under these circumstances, deciding whether to default might be no more controversial than deciding whether to claim insurance after your house burns down.

In fact, borrowers in nonrecourse states pay extra for the right to default without recourse. In a report prepared for the Department of Housing and Urban Development, economist Susan Woodward estimated that homebuyers in such states paid an extra $800 in closing costs for each $100,000 they borrowed. These fees are not made explicit to the borrower, but if they were, more people might be willing to default, figuring that they had paid for the right to do so.

Morality aside, there are other factors deterring “strategic defaults,” whether in recourse or non-recourse states. These include the economic and emotional costs of giving, the perceived social stigma of defaulting, and a serious hit to a borrower’s credit rating. Still, if they added up these costs, many households might find them to be far less than the cost of paying off an underwater mortgage.

An important implication is that we could be facing another wave of foreclosures, spurred less by spells of unemployment and more by strategic thinking. Research shows that bankruptcies and foreclosures are “contagious.” People are less likely to walk away from their home if they know others who have done so. And if enough people do it, the stigma begins to erode.

A spurt of strategic defaults in a neighborhood might also reduce some other psychic costs. For example, defaulting is more attractive if I can rent a nearby house that is much like mine (whose owner has also defaulted) without taking my children away from their friends and their schools.

So far, lenders have been reluctant to renegotiate mortgages, and government programs to stimulate renegotiation have not gained much traction.