The Nobel-Prize winning economist Robert Fogel recently told students at Cornell that “half of you (may) live to celebrate your hundredth birthday.” Fogel’s prediction goes well beyond standard projections, which envision today’s college students’ living into their late 70s. But Fogel, who has studied centuries of change in human well-being, said that conventional forecasts are usually too cautious. “In the late 1920s,” he recalled, “the chief actuary of the Metropolitan Life Insurance Company put a cap of 65 on life expectancy.”

Fogel’s forecast reminds us that, sooner or later, Americans will have to work longer and retire later. It will become economically, politically, and morally intolerable for government (aka taxpayers) to support people for a third or even half their adult lives. Our present Social Security “debate” ought to start this inevitable transformation. But it isn’t. We are in deep denial about the obvious.

Some months back, I advocated gradually raising the eligibility ages for Social Security and Medicare to 70 over the next 25 years. Even this would only reduce the large increases in future federal retirement costs. Naturally, I was deluged with fan mail. “You must be on drugs,” said one. Yet my proposal was not harsh. Eligibility ages would rise less than 2.5 months a year, barely affecting those near retirement and giving ample warning to younger workers.

Mostly, people simply don’t want to work longer. But one common objection is worth examining: age discrimination. It’s rampant, said my critics. If older workers can’t keep their jobs or get new ones, then my proposal condemns them to poverty. “The fact is that most employers don’t want older workers,” said one reader.

Although this sounds plausible, it’s an oversimplification. Even now, increasing numbers of older Americans are working. Since 1985, labor-force participation rates of men and women in their 60s have been rising, reports Boston College economist Joseph Quinn. In 1985, 25% of men from 65 to 69 were in the labor force; in 2004, that was 32.6%. Among women, the comparable figures were 13.5% and 23.3%. Indeed, as the inflow of younger workers slows, the demand for older workers should increase.

But the job market could work better for older people, and age discrimination laws are one reason it doesn’t. They act much like minimum wage laws. That is, they protect higher wages and benefits for people with jobs. But by increasing labor costs to artificially high levels, they discourage the hiring of some older workers and lead to the “downsizing” of others.

On average, older workers cost their employers more than younger workers. They benefit from seniority or accumulated merit raises. Their health costs are also higher: about double for people 55 to 64 compared with people 19 to 44, according to government figures. But the Age Discrimination in Employment Act (ADEA) makes it hard for employers to offset older workers’ higher costs.

There’s a collision between law and economics. One way companies resolve it is by offering older workers voluntary buyouts. In accepting voluntary early retirement, workers typically sign a release that they won’t sue under the ADEA. Companies may also shun hiring older workers because they entail more legal risks. The Equal Employment Opportunity Commission typically receives 16,000 to 17,000 age discrimination complaints annually. About 60% are dismissed for “no reasonable cause”; another 20% are closed without action.

Nearing 60 myself, I’m not blaming antidiscrimination laws for all of older workers’ problems. Older workers (say north of 50) who become unemployed can have a horrendous time finding new work. Being older, they have specialized skills; that makes them more valuable but also limits possible jobs. They may be told they’re “overqualified” for many openings.

But I am saying that the current system’s serious problems will worsen. Workers leave career jobs in their late 50s and early 60s, often with buyouts. Then some return to work as part-time workers or “contract workers.” They often don’t get benefits and are paid at lower rates. But because all contract and part-time employees are paid separately, a case of age discrimination is harder to make.

Our present system encourages earlier retirement among career workers and frustrates their re-employment. We could take steps to change this: Review age discrimination laws to make it easier for companies to keep career workers; allow people to buy into Medicare at age 62 or 65 while still working. I am now at an age when my body is beginning to break down. But most of us are far healthier than our parents at similar ages, and most jobs are less physically demanding. Most of us can work longer. That’s the essence of our problem, but not of our debate.