AMONG THE many unexpected consequences of the recent elections has been a renewed interest in a subject many had thought politically untouchable. Defying conventional political wisdom, a number of Republicans brought up the subject of Social Security reform during the campaign -- albeit not necessarily explaining what, exactly, that reform would entail -- and nevertheless managed to avoid defeat. At the same time, a period of brief respite in the electoral cycle has just begun. Given all of the other issues that loom ahead, this may be the last chance to talk calmly about Social Security for a long time, and the opportunity shouldn't be missed.

"Calmly" is the operative word here: For too long this debate has been deformed by ideology and politics in ways that haven't necessarily helped anyone make good decisions. Although many have pretended otherwise, the truth is that there are huge costs to reform -- and huge costs to the preservation of the status quo. On the one hand, Social Security is not, as some would have it, yet another failed, oversized government program: It is popular precisely because it has fulfilled its original purpose, which was to protect the elderly from debilitating poverty. On the other hand, there is no panacea that can somehow "save" Social Security at no cost to anyone or anything else.

Beneath the rhetoric there is a surprising degree of consensus, among those on both sides of the political spectrum who have studied the issue, about the danger Social Security faces. Because of lower birthrates and longer life spans, the United States is rapidly approaching the time when the current system, in which taxpayers effectively pay the benefits of current retirees, will become untenable: The 12.5 percent payroll tax that now funds Social Security will no longer be sufficient. A few years ago, many had thought budget surpluses would cover the costs, but those have vanished in the tax-cut-and-spending spree of the past two years. So it makes sense to consider the merits of a pension system in which at least a part of the money that ordinary workers pay into Social Security is invested in the private sector. The return on capital investment is higher, historically, than the growth in wage levels that support the payroll tax: Even in the 1930s, a privately invested system, had it existed, would have been able to distribute higher benefits than the present structure. It should not be taboo to discuss a system that might provide the poor, in particular, with higher benefits in old age, and that would encourage saving in a country that is notoriously bad at it.

Social Security reform would be an expensive project, because it means that current workers during a transitional period will have to pay both for current benefits and for their own futures. There are also costs to maintaining the current system, however, including higher taxes -- possibly far higher taxes -- significantly lower benefits and a higher retirement age. A true debate needs to consider the real costs of both options -- and the real costs of the many alternatives. Social Security reform could be accomplished with individual accounts, privately run pension funds, government-run pension funds or some combination of all three. It is important to understand the advantages and disadvantages of all of these options before making any final decisions, but the nation cannot do so sensibly without an understanding that there is no easy way out. In the context of what may prove to be a deepening fiscal crisis, an honest discussion of the costs of change will require political bravery of a kind no leading politician has yet shown.