"It makes no sense in a stimulus package," said Chad Stone, chief economist at the Center on Budget and Policy Priorities. Stone and others argue that direct payouts, such as unemployment insurance or food stamps, pump money into an ailing economy more quickly.

A) This is accurate. B) So what?

If you're judging stimulus measures purely by how fast they get money into the economy -- to deal with a recession that may well already be underway -- these tax incentives aren't the most effective way to go. (Yes, yes, I'm fully convinced of the wonder and glory and jobs that clean energy can create. It just can't create them overnight, and overnight is when we need stimulus.)

However, like ol' Don Rumsfeld said, freedom is messy. Legislating is a compromised, ad hoc business. This is a good opportunity to get something we've needed for a long time and are having trouble getting elsewhere, so I'm disinclined to be swayed by high-minded parliamentary concerns. These tax credits are good economics and good climate policy; if they are suboptimal qua fiscal stimulus, well ... tough nuts. If the donkey can get you there, no sense waiting for a pony.