The economic legacy left by the baby-boomers is leading to a battle between the generations

Voters need to understand that US demographic trends are bad for growth, and very bad for the total future tax burden. But majority rule democracy is not well-designed to find an optimize solution to the growing conflict between aging retirees and the working population that pays for the elderly benefits. 

This Economist analysis seems to conclude that inflation is the only politically feasible outcome:

(…)Sadly, arithmetic leaves but a few ways out of the mess. Faster growth would help. But the debt left by the boomers adds to the drag of slower labour-force growth. Carmen Reinhart and Kenneth Rogoff, two Harvard economists, estimate that public debt above 90% of GDP can reduce average growth rates by more than 1%. Meanwhile, the boomer era has seen falling levels of public investment in America. Annual spending on infrastructure as a share of GDP dropped from more than 3% in the early 1960s to roughly 1% in 2007.

Austerity is another option, but the consolidation needed would be large. The IMF estimates that fixing America’s fiscal imbalance would require a 35% cut in all transfer payments and a 35% rise in all taxes—too big a pill for a creaky political system to swallow. Fiscal imbalances rise with the share of population over 65 and with partisan gridlock, according to other research by Mr Eschker. This is troubling news for America, where the over-65 share of the voting-age population will rise from 17% now to 26% in 2030.

That leaves a third possibility: inflation. Post-war inflation helped shrink America’s debt as a share of GDP by 35 percentage points (see article). More inflation might prove salutary for other reasons as well. Mr Rogoff has suggested that a few years of 5% price rises could have helped households reduce their debts faster. Other economists, including two members of the Federal Reserve’s policymaking committee, now argue that with interest rates near zero, the Fed should tolerate a higher rate of inflation to speed up recovery.

The Economist does not link the IMF study which they referenced. I think it is: The Challenge of Public Pension Reform in Advanced and Emerging Economies, December 2011. Excerpt on reform options:

IMF pension reform chartA. Advanced Economies

32. Most advanced economies face the double challenge of high debt and rising age- related spending, particularly in health care (Figure 12). A number of countries with above-average levels of pension spending also face large projected increases in age-related outlays (Austria, Belgium, Finland, Greece, Portugal, and Slovenia). In some other countries with below-average levels of pension spending today, projected increases in age-related spending are substantial (Luxembourg, Korea, New Zealand, Switzerland, and the United States).

33. Pension reforms that curtail eligibility (e.g., by increasing the retirement age), reduce benefits, or increase contributions can help countries address these fiscal challenges. The trade-offs across these choices are illustrated in Figure 13. Beyond what is already legislated, with no increases in payroll taxes and no cuts in benefits, average statutory ages would have to increase by about another 21⁄2 years to keep spending constant in relation to GDP over the next twenty years.23 Relying only on benefit reductions would require an average 15 percent across-the-board cut in pensions. Relying only on contributions would require an average payroll rate hike of 21⁄2 percentage points. To keep pension spending as a share of GDP from rising after 2030, additional reforms would be needed: for each decade, retirement ages would have to increase by about 1 year, benefits cut by about 6 percent, or contribution rates increased by about 1 percentage point.

Also on future liabilities The Financial Impact of Longevity Risk, April 2012