What should be the attitude of rational intelligent people towards politics? This ancient question has been revived by a row between Jonathan Portes and Stewart Jackson.

My point here is not that Mr Jackson made a mistake. So what if he did? Twitter is a medium for snap judgments, and reasonable people will forgive folk for mistakes on it. However, Mr Jackson didn't fess up to his error, and - aided by Douglas Carswell - resorted to abuse.

This episode demonstrates several biases. There's ego-involvement; having misread the data (we've all done it), Mr Jackson saw the need to stand by his error. There's tribalism; Mr Jackson's allies support him, even though he's wrong. There's wilful ignorance, in Mr Carswell's advice to "just ignore" Jonathan. And there's an epic sense of privileged white male victimhood in the belief that folk like Jonathan "determine parameters of debate."

All this reinforces my scepticism about Jonathan's work on immigration. Introducing facts into the immigration debate is like teaching a pig to sing; it wastes your time and annoys the pig.

It also shows that politics is about power, not truth; Mr Carswell's question, "who read[s] his blogs?" is a revealing one.

In this sense, intellectuals like Jonathan (and Simon) who get involved in politics are victims of a culture clash. Their opinion that the truth matters is an example of deformation professionelle - the mistaken belief that the perspective of one's own profession has general relevance.

So, what should be the attitude of intellectuals to politics? There are three possibilities, and I oscillate between them:

- Think of politics as a laboratory for studying behaviour. Physicists have the Large Hadron Collider; we have parliament. And just as physicists don't get angry when particles prove elusive, not should we get angry when politicians display cognitive biases. It's the nature of the beast.

- Shift the Overton window. Jonathan's work showing that free migration is a reasonable position won't convince many people overnight. But shifting that window is a decades-long job. Civilization advances one funeral at a time.

- Follow Epicurus's advice, and just ignore it. The problem is that whilst this is perfectly feasible for we comfortably wealthy types, it is not so possible for the worst-off - for insurance recipients (let's avoid the loaded language of "benefit claimants") or migrants. Someone must speak for them. In doing so, Jonathan is one of the few heroes of our time.

A clarification: this post is not about immigration. A reasonable person could argue that although migration has small net economic benefits, it carries non-economic social and cultural risks.

Another thing: This episode also reveals the appalling way in which political language is misused. Carswell claims to be a libertarian. But if you're opposed to free migration, you are not - by definition - a libertarian.