Mark Thoma has posted the article ‘The Progress is Real’ quoting Paul Krugman.

Thoma adds the insight:

That brings up the second point. Republicans in Congress have blocked efforts to implement fiscal policy measures over and above the initial stimulus effort (and they would have blocked the Fed as well if they had the power to do so). An aggressive infrastructure construction effort would, for example, buttress monetary policy and speed the recovery, and it would also provide benefits (including higher future growth) that exceed costs, but Republicans are not going to let that happen. This is like hiding half of the medicine a patient needs for recovery based upon medical quackery, and then asking why the doctor is doing such a lousy job.

This is the metaphor I always think about, but perhaps Thoma states it better than I would.

I think about the example of the use of anti-biotics. If you are going to use anti-biotics, you must use the full dose. If you don’t use the full does, you leave behind the organisms that were able to survive the partial dose. These are the organisms that mutate into anti-biotic resistant ones. At some point, when you do apply full doses of the previous anti-biotic, they no longer work because of the partial doses that went before.

In the case of the economy, the more often you apply a stimulus that is too weak, the more likely you are to develop an economy that becomes resistant to stimulation. In this case, the stimulus that would have been big enough when you first applied the weak stimulus is now no longer big enough. You now have to apply a stimulus that is even bigger than the one that would have worked in the first instance.