Wars cost money, even if President Bush's wartime tax cuts encouraged us to believe otherwise. So House Appropriations Chairman David Obey (D-Wis.) has made a modest proposal: To fund any escalation in Afghanistan with a surtax that would hit the top five percent of tax payers only. In the abstract, I think Obey's plan represents an important point. Budgeting is the art of prioritizing, and when we agonize over non-discretionary spending while blithely passing big war budgets with a flick of congressional "Yea" votes, we shield ourselves from the costs of war, stacking the deck in favor of foreign adventures, and against necessary domestic spending.

But there's a reasonable concern with Obey's specific proposal.

The right way to tax a war is to impress on the electorate the idea of shared sacrifice. So long as most Americans consider war efforts something we export entirely to our armed services, the choice to wage war feels something like a non-recourse loan for most voters. If it works out, America wins. If it doesn't work out, at least I didn't have to do anything. Enshrining the value that wars have a cost we should bear collectively is a good principle.

But that's not really the principle Obey is advancing. A surtax on the top five percent of tax payers wouldn't be a shared sacrifice. It would be the highest percentiles paying for a war effort fought mostly by the lower percentiles, which is, it turns out, essentially what we have already. A broader-based war tax would go further toward this idea of "shared sacrifice." But in the aftermath of a recession, a broad-based tax increase is almost certainly out of the question -- not merely among conservatives, but among moderates and liberals who don't want to burden the fragile job market.

So I'm with Mark Thoma. A surtax might be palatable, but it's not a shared sacrifice. A general tax would be a shared sacrifice, but it wouldn't be palatable -- among the electorate or among White House economists who want to avoid broad-based taxes until the economy is healthier. In any case, it sounds like the war tax is dead, anyway.

Update: I misread the specifics of Obey's proposal, which would tax all Americans at a progressive rate, exempting those earning under $30,000. It would also give the president the prerogative to waive the tax until 2012 if the economy takes a while to pick up. All told, not a bad idea, and not nearly as limited as I imagined.