I have in the past complained about centrist utopianism. Tim Montgomerie in the Times offers an example of this. He points out "nothing has actually done more in world history to ensure the poor don't stay poor...than the advance of free trade" and then asks: "Do politicians such as Mr Corbyn really want to roll back globalization?"

This overlooks an important fact - that the pace of globalization has already slowed markedly not because of leftist politicians but because world capitalism is faltering.

Figures from CPB show that the volume of world trade grew by only 0.8 per cent in the last 12 months.This isn't a sudden dip, but seems part of a post-crisis trend for slow growth. In the 15 years to December 2007, world trade grew by 7% per year. Since then it has grown only 2% per year.

This is why I accuse Tim of centrist utopianism; his claim that world trade will lift people out of poverty ignores the fact that this trade has slowed. To paraphrase Tom Paine, he is admiring the plumage but ignoring the sick bird.

There are many possible reasons why world trade has slowed. One possibility is that greater uncertainty about exchange rates or the availability of credit are discouraging firms from exporting. Some firms have become more aware of the impossibility of overseeing long supply chains and so are reshoring production. Perhaps the same depressed animal spirits that are suppressing capital spending are also suppressing investment in export sales' efforts. Or perhaps poorer nations such as China are victims of their own success: rising wages mean their cost advantage is diminishing and with it western firms' desire to source goods from them.

This might be important. We know that a country can reduce abject poverty by opening itself up to global trade and attracting investment to take advantage of its low wages. But this cannot go for long: there are many cases of countries falling into a "middle income trap" in which growth stagnates and with it the pace of poverty reduction. As Lant Pritchitt and Larry Summers wrote (pdf):

Regression to the mean is the single most robust finding of the growth literature, and the typical degrees of regression to the mean imply substantial slowdowns in China and India relative even to the currently more cautious and less bullish forecasts.

One reason why stock markets have reacted so badly to China's slowdown is that they fear this very possibility.

This, though, implies that formal globalization alone might not be sufficient to ensure a continued rapid pace of poverty reduction.

The issue, therefore, is not merely whether capitalism is desirable or not. It is also: how healthy is it? Partisan cheer-leading pieces such as Tim's overlook this crucial question.