In Thursday night’s debate, Vice President Joe Biden will almost certainly go after Representative Paul Ryan’s Medicare plan. And why shouldn’t he? It’s unpopular. But I’d like to make a case for that plan. It’s the best thing the Romney-Ryan campaign has going for it.

First, let’s define the problem. Today, Medicare costs about $550 billion. By 2020, according to the Congressional Budget Office, it will cost more than $1 trillion, sucking money away from every other government program.

According to the Urban Institute, the average couple in 2010 had paid $109,000 in Medicare taxes during their working years but would be able to receive about $343,000 in benefits. A chunk of that $234,000 gap will be paid for by their grandkids. That should weigh on the conscience of every American over 55. You’re supposed to help your grandkids, not take from them.