Here's a theory: one of the most important, yet under-rated, divisions in politics is that between centralizers and decentralizers.

This isn't quite the same as the authoritarian-libertarian axis used by Political Compass, or Haidt's liberty-oppression axis. For one thing, the axis I have in mind is often an instrumental one - it's about how our values are best achieved - rather than one of values themselves. For another, some centralizers can be quite libertarian: some Blairites, for example, favour strong central political leadership and yet are socially libertarian. And for yet another, some forms of central organization can be freely entered into.

And it's certainly not the same as the left-right axis. For example, Seamus Milne and left-libertarians are both on the left, but on opposite sides of the centralizer-decentralizer axis. And that subset of right-libertarians who are sincere and consistent are on the same side of this axis as we left-libertarians, whereas securocrats such as Theresa May are on the opposite.

Here are some examples of the centralizer-decentralizer axis:

- Vote Leave's demand to "take back control" appealed to some decentralizers - even though it amounted to just shifting power from Brussels to London. (The fact that the slogan appealed so much to authoritarians is more evidence that this axis isn't the same as the authoritarian-libertarian axis.)

- We supporters of greater worker democracy are decentralizers whilst our opponents are centralizers.

- Supporters of a citizens income come from left and right, but are decentralizers. Those who favour conditional or needs-based forms of welfare, on the other hand, are centralizers.

There is, though, a more pressing example of my axis: the split in the Labour party. There are two different visions of the party. One - that of the centralizers - sees it as primarily a Westminster party. This was expressed by John McTernan's quip: "who cares about the grassroots?" The other vision is that of the party as a social movement which aims to change politics from the bottom-up. As Matt Bolton puts it:

If only the party could get enough members, enough boots on the ground, it can counteract the power of the media, build concrete connections with local communities and activist groups, and fundamentally shift the terrain of politics - the very meaning of 'electability' itself - for good.

This is a backlash against the centralizing of the Blair years, in which - as Phil says - class atomization allowed the party to become dominated by Blair.

Although we think of this division between centralizers and decentralizers as being between left and right today, it hasn't always been so: in its hey-day, when the Labour movement comprised both parliamentary and industrial wings, many trades unionists were quite right-wing.

Instead, the division should be regarded as being about how to achieve social change: can it be done merely through conventional parliamentary means in which a "strong leader" and good messages break through to voters? Or does it also (or instead?) require a broader social movement to counteract the massive ideological and media obstacles the party faces?

My sympathies are with the latter. But that's not my point. Instead, the point is that there is mutual incomprehension here, in part because of a failure to see what the issue is. This, I think, contributes to the mutual loathing between Corbyn and lobby correspondents.

And here, even the so-called neutral media are in fact horribly biased here. The BBC's political reporters identify politics with what goes on around parliament: "political correspondent" and "Westminster correspondent" are interchangeable. This represents an unthinking bias towards the control end of the axis, and as such functions not just as a bias against Corbyn but a bias against understanding as well.