Matthew Yglesias recalls a preferred social security framework from shortly after dawn of the second age. It's full of progressivity, mandatory private accounts, moral hazard mitigation, and refundable tax credits.
As for as I can see, however, it boils down to welfare for indigent seniors. I don't see, for example, how forcing private savings, sequestering the funds, then granting tax credits to cover the cost does anything to eliminate the "moral hazard." But then, I don't really believe there are all that many people so happy with their lives on the dole that they wouldn't lift a finger to improve their lot. I'm sure there are some, but it doesn't cost all that much to support someone in poverty, so unless there are hordes happy to live in dirty, vertical hovels, I can't see the "moral hazard" of the arrangement ruining the republic. Did we actually spend more last year on people in poverty than we did on Iraq? Why do people who would never choose to live in poverty themselves always assume that everyone else is just looking for their chance?
It must be hard to have so many policy tools at your fingertips that you can't figure out how to use them all.