Nick Cohen describes how "diversity" can be used to justify illiberal inequality. I suspect this might be true in another way.

What I mean is that there might be less diversity of opinion and character now than there was in the past. Naturally, I can't quantify this, but consider some of the types of character and belief which I think are not as common as they should be:

- small state Keynesians. It's possible to favour both fiscal activism and a small state - as Keynes himself did. But almost nobody now falls into this camp; pro- and anti-fiscalists map quite closely onto pro- and anti-big government.

- free market pessimists. Very many free marketeers are optimistic about the potential for technical progress and growth, whilst secular stagnationists tend to be leftists. There's no necessary reason for this: Ricardo, for example, favoured free markets whilst worrying about a stationary state. This opinion, though, is rarely heard.

- free market egalitarians. It's possible to oppose many forms of equality because they are symptoms of rigged markets. With one or two exceptions, though, few do so; free marketeers tend to be apologists for the 1%.

- Oakeshottian conservatives. In one strand of conservatism, there's a melancholy tendency which believes that some problems are insoluble and which mourns the decline of traditional ways of life. Such a strand should be hostile to a rationalist managerialism which treats politics as a series of problems to be solved and which paves paradise to put up a parking lot. Such a view is now rarely heard, and the Tories are mostly the party of bosses - which is not something Oakeshott would have been comfortable with.

- Left Hayekians. Centrally planned economies are a stupid idea said Hayek. He was right. But big companies are centrally planned economies too, with the flaws this entails. A few Hayekians point this out - but not as many as should.

In addition to these under-represented opinions, there are also some character types which are waning. I'm thinking of the mega-rich with a sense of noblesse oblige: for every Gates or Buffett I suspect there are more narcissists with grossly excessive senses of entitlement. There are also fewer bachelor dons who published little but had great influence; I wonder how today's university bosses would react to Tolkein writing about elves or Lewis about Narnia. And there are also, I fear, fewer highly intelligent working class autodidacts; the deaths of Bob Crow and Bob Hoskins this year are to be mourned not just for the loss of talent but for the loss of particular types.

From these perspectives, what we have today is too little diversity and - perhaps - a loss of diversity in recent decades.

I suspect there are (at least) two reasons for this. One is a form of groupthink - perhaps accelerated by social media and asymmetric Bayesianism - which divides politics along narrow left-right lines.

The other is the rise of managerialist ideology which undermines professional virtues and which is intolerant of dissent; the fact that it is even possible for an academic to be disciplined for insubordination shows that management is the enemy of diversity. When a boss - in the state or private sector - calls for "diversity" what he really means is: "let's hire some women, blacks and gays who agree with me". Whilst this is to be welcomed in one sense - "minorities" could hardly do a worse job than middle-aged white men - it is a very partial form of "diversity". And it can be used to disguise a loss of diversity and rise of illiberalism in other senses.