Older readers might remember a TV show called "How", which began - in unPC fashion - with the presenters raising their hands and shouting "How". I was reminded of this because the launch of Angela Eagle's leadership bid raised exactly this question.

She said:

Jeremy Corbyn is unable to provide the leadership that this huge task needs. I believe I can.

How?

She continued:

I will unite, I will not divide. I can bring our Party together again.

How?

I fear this lack of important detail is not an idiosyncratic failure of Ms Eagle's. Instead, it illustrates John Gaffney's point that Labour "doesn't know what leadership is, doesn't want to know, and doesn't like it - so doesn't know what it entails." This, I think, is true in three ways.

First, leadership - like much else - is about mechanisms. The question is: through what precise mechanisms does leadership translate into results? Ms Eagle doesn't answer this question. She is guilty of what I complained about recently: the "leadership-?????-success" fallacy.

Secondly, what matters is not so much getting the best person to be leader as getting the right match between the candidate and the job. As Boris Groysberg has shown (pdf), managers of similar ability are successes where there's a match between their skills and the organization's needs, but not where there is a mismatch.

This requires that Labour understands precisely what qualities it needs in a leader, and identifies the individual with those qualities. Wishful thinking about what would happen if only the party had a "proper leader" is not good enough. Instead, the question is: what exactly is the shape of the hole we're trying to fill, and who fits that shape?

There's something else. One key feature of good leadership in business is the ability to get feedback and act upon it. Two of the questions Bloom and Van Reenen ask in their work (pdf) assessing management competence are:

How well do companies track what goes on inside their firms, and use this for continuous improvement? [And] do companies set the right targets, track the right outcomes and take appropriate action if the two are inconsistent?

By these criteria, Corbyn's critics* are abject failures. They failed to take feedback from their defeat to him last year. He didn't win so crushingly because he's a political genius - he spent 32 years in parliament without ever being hailed as such - but because his opponents (except perhaps for Liz Kendall) were offering little but vacuous marketing-speak. Corbyn's critics should have learned from this that they need to develop some kind of inspiring vision of centre-left principles and policy. With precious few exceptions, though, this is still lacking. Corbyn's opponents seem not to have learned that they are not entitled to run the party, but must earn the right to do so.

Now, I don't say this to defend Corbyn. His inability to placate fractious MPs and his downright bizarre decision to attend a Cuba Solidarity meeting when there were far more important things to do suggest he isn't up to the job. In this context, though, the failure of his critics to understand what leadership means is simply tragic.

* I don't want to use the word "right" in this context as I'm not sure the left-right distinction is helpful in this context.