At this point the economic case for austerity — for slashing government spending even in the face of a weak economy — has collapsed. Claims that spending cuts would actually boost employment by promoting confidence have fallen apart. Claims that there is some kind of red line of debt that countries dare not cross have turned out to rest on fuzzy and to some extent just plain erroneous math. Predictions of fiscal crisis keep not coming true; predictions of disaster from harsh austerity policies have proved all too accurate.

Yet calls for a reversal of the destructive turn toward austerity are still having a hard time getting through. Partly that reflects vested interests, for austerity policies serve the interests of wealthy creditors; partly it reflects the unwillingness of influential people to admit being wrong. But there is, I believe, a further obstacle to change: widespread, deep-seated cynicism about the ability of democratic governments, once engaged in stimulus, to change course in the future.

So now seems like a good time to point out that this cynicism, which sounds realistic and worldly-wise, is actually sheer fantasy. Ending stimulus has never been a problem — in fact, the historical record shows that it almost always ends too soon. And in America, at least, we have a pretty good record for behaving in a fiscally responsible fashion, with one exception — namely, the fiscal irresponsibility that prevails when, and only when, hard-line conservatives are in power.

Let’s start with the common claim that stimulus programs never go away.

In the United States, government spending programs designed to boost the economy are in fact rare — F.D.R.’s New Deal and President Obama’s much smaller Recovery Act are the only big examples. And neither program became permanent — in fact, both were scaled back much too soon. F.D.R. cut back sharply in 1937, plunging America back into recession; the Recovery Act had its peak effect in 2010, and has since faded away, a fade that has been a major reason for our slow recovery.