Robert Samuelson of Newsweek has thrown down the gauntlet for the 2008 presidential contenders: What would they do about the huge budget costs of aging baby boomers?

The numbers are daunting indeed. By 2030, when there are projected to be more than 70 million people over 65 in the U.S., the combined costs of Social Security, Medicare and Medicaid are expected to consume 75% of (today's) budget, crowding out all other spending, if not bankrupting the country altogether. But because most of the proposed solutions are politically unpopular, Samuelson observes, it's been easier for politicians (of both parties) to do nothing.

Samuelson's suggestion: commission a half-dozen think tanks, split between liberals and conservatives, to submit 35 pages each outlining a vision of the future, including specific policy planks about benefit cuts, eligibility ages, tax hikes and the like. Under his plan, a book compiling the papers would be published in time to drive the election-year debate.

"If published in April, the book might prod the presidential candidates to address the future," Samuelson writes. "If they didn't, it would measure the enormity of their evasion."

Samuelson's challenge is all to the good, but the framing is too narrow, too Beltway. Rather than merely craft a policy that averts the fiasco, we need a vision that fosters a renewal, both social and individual. Aging boomers are more than liabilities, after all, they are also assets. Changing the starting point of the discussion also changes the end result. Rather than muddle through, why not breakthrough?

Certainly, longer working lives are likely to be a feature of boomers' encores, but that reality will be much more appealing if work itself is re imagined: encore careers at the intersection of personal meaning, continued income and social impact.

Presidential candidates looking for a creative response to Samuelson's question are welcome to adopt the encore idea. Meanwhile, let's take up his challenge as well, crunch some numbers, and get cracking on our own 35-page proposal.