A lot of commenters are asking why this sort of funding is in the stimulus bill in the first place,and call it pork. They’re missing the point: the point of the stimulus bill is to stimulate the economy, both in the short and the long term. Funding science does exactly that; it helps pay for scientists, experiments, equipment, and more. I have written about this before. Funding science pays off multiply in the long term; it always has.Two things:
1) No, the stimulus bill is not meant to stimulate the economy in the long term. There is no evidence that the economy needs stimulating in the long term, considering the U.S. is the wealthiest economy in the world. If the bill was meant to stimulate the economy in the long term, we should all be screaming bloody murder, because they'd be throwing over $800 billion dollars at a demonstrable non-problem. It is meant to stimulate the economy in the short term, and it's not very clear that science spending would have any such effect.
2) Even then, the question is not whether science pays off, but how well it pays off relative to other types of spending, in terms of speed and expected value. The value of many kinds of science spending are highly uncertain (science being about discovery and all); the deadweight losses caused by taxing the economy to finance that spending are certain. Insert Keynesian "It doesn't matter what you spend the money on" argument here, but it does matter the speed at which it gets spent.
I agree with Plait that the anti-science Republican rhetoric is ridiculous. Furthermore, volcano watching could turn out to be immensely important and I'd not be opposed to government funding thrown that way, in a normal science funding bill. But stimulus it ain't.