There's one reaction to the UK's lack of meaningful economic recovery that is surprisingly absent.

To see it, remember that a big reason for our slow growth is a lack of capital spending; the volume of business investment, though up from its 2009 low-point, is still 11.6% below its 2007Q4 peak.

But why is capital spending so weak? There are lots of possibilities: the slowdown in technical progress has created a dearth of investment opportunities; fears that banks will restrict future credit lines are causing firms to hoard cash; falling real wages are encouraging labour-capital substitution; and spare capacity and weak demand mean there's little need to expand.

I don't want to reject any of these. But there's another possibility, raised in a new paper by Charles Lee and Salman Arif - that investment and the recovery are held back by depressed animal spirits.

They point out that business investment is well correlated with investors' sentiment towards shares. My chart shows that a similar thing is true in the UK. We can measure sentiment by the ratio of Aim stocks to the FTSE 100; Aim shares tend to be smaller, less well-known and more speculative than bigger shares, and so high prices for them are a sign of high spirits. You can see that this ratio has tended to predict business investment, with a lag - the lag being because it takes time for investment decisions to translate into actual spending.

Of course, a correlation between investor sentiment and capital spending might exist simply because rational expectations of the future determine both. If so, then current weak sentiment and weak investment are a sign of weak future growth.

But Lee and Arif's work suggests this might not be so. They estimate that, in most advanced countries, high investment leads to weaker GDP growth and falling profits. That's exactly the opposite of what you'd expect if sentiment and investment were rationally determined.

This leaves us with another possibility - that it is irrational animal spirits that drive sentiment and capital spending. And herein lies the point that is not widely made. It's that the economy is being depressed in part by company bosses being irrationally pessimistic. We're paying the price for stupidity in boardrooms.

Such a reaction should appeal to both Keynesians - who coined the phrase "animal spirits"? - and to government supporters wanting to deflect blame from Osborne.

And yet it is rarely heard.I suspect one reason for this lies in the power of managerialist ideology. Whilst the ruling class are quick to attribute irrationality to ordinary people, they are blind to the possibility that irrationality can also be found at the top of hierarchies.