One of centrists' great conceits is that they are rational and moderate whist the left are fanatical ideologues. New Labour for example championed "evidence-based policy-making"; Chris Leslie claimed (pdf) that they favour "evidence not ideology": and Steven Pinker has a BBC radio show telling us how to think better. Two recent interventions remind us that all this is self-serving nonsense.

One came from David Blunkett, who told the Today programme (2"57' in) that if we let in a few refugees, "Nigel Farage might end up being Prime Minister". That of course is mere speculation. What is evidence is that the UK does not get many asylum applications. There were only 29,456 in 2020, compared to 102,525 in Germany, 37,860 in Greece, 86,380 in Spain and 81,735 France. Lord Kerr is right: "we are not the preferred destination in Europe" for refugees. And given that the labour market impact of migration is tiny, we could easily accommodate more. The only "migrant crisis" is that of the migrants themselves: from the UK's point of view, there is no crisis - only maladministration and cruel racism.

The other intervention came from Tony Blair. He claims that Labour "is seen as being for everyone other than the hard-working families who feel their taxes aren't spent on their priorities."

Seen by whom? Not by hard-working families themselves. As Ben Walker has pointed out, in the 2019 general election Labour out-polled the Tories among working-age voters living in households with annual incomes below £100,000. Labour's problem is not with working people; it is with the retired.

Blair's detachment from the evidence does not stop there. He goes on to claim that Labour must "push the far left back to the margins" and reject "the old-fashioned statist view of the left". This misses the fact that the "far left" is rejecting old-fashioned statism. It is fighting against the Tories assault upon civil liberties. And the "defund the police" slogan of Black Lives Matters, whatever its merits or not, is a profoundly anti-statist sentiment.

Of course, there is an authoritarian statist tradition on the left. But it is one of which Blair himself was a big part: New Labour created over 3000 new criminal offences and greatly increased the prison population, trends which the "far left" deplore.

There's another odd thing about Blair's comments. In attributing statism to the left, he omits to point out that its is the Tories who are increasing the size of the state: the OBR forecasts the tax burden rising to its highest level since the early 50s.

This increase will happen because of weak GDP growth, so public services must be financed by taxes rather than economic growth.

Blair, however, makes no mention of this long-term economic stagnation. Which is no idiosyncratic omission, but rather a consistent theme of centrists. Leslie made little reference to the financial crisis and its aftermath in his Centre Ground pamphlet, and the Independent Group/CUK omitted mention of it in its launch statement.

This blindspot matters enormously. Economic stagnation is a major cause of the current state of our politics. As Ben Friedman showed in 2006, hard economic times fuel reactionary politics - hence Brexit and anti-migrant bigotry. If Blair is sincere in wanting "liberal, tolerant" politics, he needs some way of kickstarting growth.

Here, though, it is the left that is evidence-based whilst the centre is trapped by outmoded ideology. Blair says Labour needs "a new future-oriented policy agenda based on an understanding of how the world is changing." But this is just what Corbynite economic policies offered. They were based upon the recognition that the world has changed since the 90s, being characterised by stagnant productivity, negative real interest rates and the concentration of wealth and power among the 1%. By all means, argue with their remedies, but I don't think you can charge the left with not seeing that the world is changing.

Which brings me to a curious phenomenon. Mainstream economists acknowledge the need to kickstart productivity; the role of fiscal policy in fighting stagnation; and the fact that immigration in economically benign. Blunkett and Blair seem much less alive to these facts. The political centre is now very different from the economic centre. And it is the left, more than some centrists, that is evidence-based.