TPC sponsored a fascinating debate today between John McCain’s top policy adviser, Doug Holtz-Eakin, and Barack Obama’s senior economic adviser, Austan Goolsbee. More than anything, I was struck by how much time each spent criticizing the other guy’s fiscal plan rather than promoting their own.

The discussion coincided with TPC’s release of an updated analysis of the candidates’ tax plans. The new report concludes that both will significantly increase the deficit over the next decade. Including interest costs, Obama would do so by $3.4 trillion, while McCain would raise the deficit by $5 trillion. The Obama plan would cut taxes for most people, but raise levies significantly on the very wealthy. McCain, but contrast, would cut taxes for nearly everyone, but provide by far the biggest reductions for those making the most money.

McCain’s primary policy goal is economic growth, Obama’s is progressivity. These are big and interesting contrasts, and it would have been nice to learn more about what drives their bosses’ agendas. But, instead, I mostly heard why the other candidate’s plan is so awful.

Goolsbee talked a lot about McCain’s “budget shammery.” It is a nice turn of phrase, but neither candidate gets high marks for transparency. Both prefer to use a budget baseline that assumes the Bush tax cuts will go on forever and that the Alternative Minimum Tax will be permanently “patched.” I understand why, since that appears to give them more money to pay for campaign promises. But, in truth, both candidates are hiding a lot of fiscal irresponsibility behind these wonky arguments over baselines.

Holtz-Eakin gets credit for giving a straight answer to a very important question; How much tax revenue is right? In the short term, he said about 18 percent of Gross Domestic Product. Since he also said McCain wants to balance the budget by 2013, he is suggesting that spending also ought to be about 18 percent of GDP. That implies some pretty tough cuts in current government programs, which cost more than 20 percent of GDP.

There are serious questions about whether McCain could get there, and what kinds of spending cuts it would take, but at least I came away with some idea of where he is headed. Goolsbee, by contrast, ducked the question at least twice. The closest he came to an answer was to concede that Obama’s 2013 deficit would be lower than this year's, which will exceed $400 billion. Not exactly a high fiscal bar.