Is high personal debt a threat to the UK economy? Vince Cable thinks so. He told radio 4 yesterday (9'28" in):

A sudden change in household confidence - people beginning to get alarmed about their debt levels - could trigger a serious downturn.

This is a more ideological claim than you might think.

First,some economics. As Simon says, the question of what is the right level of debt is a very tricky one, not least because so much depends upon the distribution of debt. In fact, it's possible that high consumer debt far from being a bad thing is in fact to be welcomed, because it's a sign that households might be rightly optimistic about the future.

What's more, history tells us that consumer-led downturns are quite rare. Since data began in 1955, there have been 45 calendar quarters in which real GDP fell. In only 11 of these did consumer spending fall by more - and several of these were in response to increases in sales taxes (1968Q2, 1975Q3 and 1979Q3) interest rates or oil prices (1980Q4). It's rare therefore for an exogenous drop in consumer spending to trigger a recession. More often, consumer spending acts as a stabilizing force.

Recessions are far more often due to errors by those in power than to consumers: policy-makers setting interest rates wrongly; corporate bosses investing too much and then retrenching; or bankers cutting credit after making bad loans.

This is why I say Cable's claim is ideological. In inviting us to worry about the alleged irrationalities of consumers, he is deflecting attention away from what has more often been the threat to our prosperity - the errors of our rulers*. In this way, a question that might undermine the legitimacy of the rich and powerful - do bosses, banks and policy-makers know what they are doing? - is not asked.

From this perspective, there's a link with the fuss over Peter Tatchell being "no-platformed." The kerfuffle over students' wanting to limit cognitive diversity distracts us from a more pernicious form of no-platforming - the Westminster bubble's narrowing of the Overton window to exclude many ideas from debate. It expects us to give a toss what a criminal associate thinks about Brexit whilst underplaying or ignoring more serious issues such as the cases for a citizen's income or worker democracy or what to do about the UK's lamentably low productivity.

What we see in both cases is a means of shoring up inequalities of power: fretting about consumer debt or silly student politics whilst underplaying the greater defects of the powerful help to legitimate the latter.

You might think I'm making a Marxist point here. Maybe. But I'm also channelling another classical economist - Adam Smith:

We see frequently the vices and follies of the powerful much less despised than the poverty and weakness of the innocent. (Theory of Moral Sentiments, I.III.29)

* In fairness, such errors might be occasionally inevitable because we can only have limited knowledge of complex emergent processes.