How pinched and petty-minded is the attitude that underlies so much of the comment on Jeremy Corbyn. Many of our grandest pundits dismiss him because they reckon he has no chance of becoming Prime Minister.

For this school of commentary, success is all that matters in politics. If you are not doing everything to maximise your electoral chances, you are an idiot whose views deserve to be ignored because you yourself are never going to get to the top.

Even in its own terms, this approach is blinkered. For it is seldom possible to know in advance whether a political project is going to succeed or fail. Not long ago, the commentariat told us David Cameron would fail to get a majority at the general election, and that Corbyn had no chance of becoming Labour leader.

But there is a deeper reason for objecting to the dismissal of political ideas simply because the person holding them looks doomed to failure. For here is a dreadful, self-imposed limitation on freedom of thought.

Inconvenient ideas, which challenge the way things are being done in September 2015, are dismissed simply because the person advancing them is eccentric: he has a beard (so did the great Lord Salisbury), is said to have gone round East Germany with Diane Abbott on a motorbike (wonderful way to see the place, one might have thought), and has been known to eat cold baked beans straight from the tin (what an economy of time, energy and money).

At all times and in all places, human beings dismiss some ideas as too outlandish to merit any kind of fair-minded consideration. But in the Labour Party under Tony Blair, virtually all ideas except those held by the Leader and a few others were treated with contempt. Hence the low quality of the remaining Blairites: these dismal careerists have never been encouraged to have an original or provocative or at least faintly interesting opinion in their lives, and now that their Leader has left the stage, are like robots which have lost radio contact with their controller.

In the Labour Party under Blair, you didn’t get put in prison for having dissident opinions. But you did get put in a box marked “eccentric”, or in Corbyn’s case, “loony Left eccentric”. In career terms, you were never going to get anywhere.

The inestimable service that Corbyn has done to our democracy in recent weeks is almost entirely overlooked. He could just have said of the House of Commons: this place is a waste of time and I’m going to go off and foment revolution.

He instead stood for the leadership of his party, won it by inspiring a quarter of a million people to vote for him, and came to the Dispatch Box to convey something of their views.

The response of the commentariat is to dismiss the views of those quarter of a million people as loony too. I have probably done that myself: have shaken my head and wondered how anyone could be naive enough to agree with Corbyn about defence, or renationalising the railways, or whatever it might be.

But in conversation with Corbyn supporters, I find that although (to my way of thinking) they are misguided, they are not, for the most part, lunatics. They are deeply dissatisfied with the present set-up, which they think concentrates power in too few hands.

They detest inequality, and feel that since 1983, when Neil Kinnock became Labour leader, they have generally been ignored or taken for granted by Britain’s main left-wing party. They feel their freedom is circumscribed, not by oppression, but because they themselves are ignored, and are just expected to do as they are told – a horrible feeling which exists in many private corporations too.

In Scotland, this feeling became so strong that Labour voters turned en masse to the SNP. Something like that could happen in England: indeed to some extent it already has, with millions of Conservative and Labour voters turning to UKIP.

De Tocqueville, in his great work on the Ancien Régime and the Revolution, explained why free institutions, in which discontent is expressed, are as useful to the powerful as to the weak:

Les institutions libres ne sont pas moins nécessaires aux principaux citoyens, pour leur apprendre leur périls, qu’aux moindres, pour assurer leur droits.

Corbyn himself may fail, but the mood of febrile dissatisfaction which has taken him to the Labour leadership needs to be addressed, not ridiculed.