Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" and of the new book "Governing America."

Aaron Carroll: Debate shed little light on Medicare, Medicaid

No one will confuse this debate and the last one. Both participants came prepared to fight. There are many who will say that Vice President Biden was too forceful, or was disrespectful, but for supporters of the president who wanted to see a more energetic response to the Republican campaign, Biden's performance was likely a balm.

The polls will tell us in the next few days, but if Biden's actions tonight inspire the base as I think they likely will, then the president will see some benefit.

Of course, my main interest is health policy, and in that respect, tonight was a bit disappointing. The entire discussion centered on Medicare. For all the bluster between the two campaigns, the differences between them on that program for the next decade are small.

For all the talk about the financial risk Medicare holds, neither wants to cut it severely soon. On Medicaid, however, the differences are stark; that program didn't come up at all.

I also was appalled that raising the Medicare age of eligibility was tossed off as an obvious thing to do. That's a terrible idea.

Dr. Aaron E. Carroll is an associate professor of pediatrics at the Indiana University School of Medicine and the director of the university's Center for Health Policy and Professionalism Research. He blogs about health policy at The Incidental Economist and tweets at @aaronecarroll.

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