Simon Wren-Lewis on ideology and demand denial (I agree with his comments on the "asymmetry" in the views of Keynesian and non-Keynesian economists, and that in many cases ideology is the likely explanation for the differnece):
Ideology and Demand Denial, mainly macro: ...What the debate over fiscal policy has revealed is an underlying generic antagonism towards Keynesian analysis.
There is an asymmetry here. Keynesian economists do not deny that productivity or other supply side shocks can often be important. On the other side there appears to be, among many at least, a belief that Keynesian economics is never relevant. What this amounts to is what Krugman and others call demand denial. Yet the basis in economic theory for demand denial appears very unclear. Say’s Law, or maybe some kind of quantity theory with fixed velocity, would do it – but these were really bad ideas that the profession dismissed many decades ago. ...
Keynes had a number of thoughts on this, as the following from the General Theory shows (‘it’ in the first sentence is a theory that involves demand denial).That it reached conclusions quite different from what the ordinary uninstructed person would expect, added, I suppose, to its intellectual prestige. That its teaching, translated into practice, was austere and often unpalatable, lent it virtue. That it was adapted to carry a vast and consistent logical superstructure, gave it beauty. That it could explain much social injustice and apparent cruelty as an inevitable incident in the scheme of progress, and the attempt to change such things as likely on the whole to do more harm than good, commanded it to authority. That it afforded a measure of justification to the free activities of the individual capitalist, attracted to it the support of the dominant social force behind authority.
Now beautiful though this passage is, a good deal has changed since 1936. New Keynesian theory is a ‘consistent logical superstructure’, so there is no intellectual prestige involved in denying its relevance (except, perhaps, to fellow believers). Yet two sentences still ring true. The first is the idea that austerity is virtuous. Some of the popular discourse around fiscal policy has moral overtones, perhaps stemming from the idea that governments, like individuals, have to practice self control. Now while I think seeing economics as a morality play is generally unhelpful, in the case of fiscal policy there is a problem of deficit bias: governments over the last few decades have tended, on average, to spend too much or tax too little. (Some particular evidence, and a fairly comprehensive discussion of reasons for deficit bias, can be found here. ...) However deficit bias is a long term problem and a recession is not the time to start dealing with it.
The final sentence from Keynes also still rings true. One explanation for demand denial is that it has ideological roots. In the real world we have the problem of ensuring aggregate demand matches supply, and this requires state intervention – normally monetary policy. For those who want to argue that state intervention in the economy is generally a bad thing, it is embarrassing to acknowledge that there is one area where it is essential. But I get no joy in seeing ideology mess with economics, and so I would be more than happy to be convinced that there was another explanation for demand denial.