Brad DeLong wants to keep Social Security away from Congress' grubby little paws:

...I'm attracted to the Federal Reserve model. Get the cabinet secretaries out as Trustees of Social Security. Replace them with guys appointed for fourteen-year terms. Mandate that they keep the system in actuarial balance--just like the Federal Reserve has a mandate to preserve price stability. And have them raise and lower the retirement age a bit at a time as the fortunes of the system wane and wax.

Fair enough. His commenters also (sort of) bring up a point I've always liked -- differential retirement ages. The standard argument, after all, is that longer life expectancies will enable us to raise the retirement age with some fairness. But only some people will benefit here. I, for instance, sit at my desk all day and either search around on google or talk on the phone. If I retired at the age of 70 or later, assuming I live that long, it wouldn't be a huge deal. A coal miner, meanwhile, probably ought to retire at the age of 55 or so—modern medicine might help him or her deal with arthritis and other disabilities, but eventually the body wears out and you can't heave around a pickaxe all day. Meanwhile, that manual laborer isn't going to get retrained for a desk job at that late age, so where does that leave him?

So some people retire later, some people retire earlier. How does this all shake out? Based on this chart, the overwhelming majority of workers seem to have jobs with relatively low physical stress (management or office). So they would all get raised retirement ages and Social Security would be on even sturdier footing without forcing the coal miners to keep heaving their pickaxes at the age of 70. Hm? On the other hand, this downplays the importance of mental stress, so maybe it would never fly, I don't know.