It is surprising how bad politicians can be at politics. The trouble over the national insurance increase for the self-employed was wholly unnecessary. In sporting language, it was an unforced error, avoidable by a smidgeon of foresight. Mrs May tells us that she admires Geoff Boycott, but imagine if she and Mr Hammond had been a brace of batsmen and he had been in the commentary box. Mr Boycott could be accused of relishing in castigation, even by Yorkshire standards. This time, he would have been justified.

He could have gone on lay into the fielders. If anything, modern ministers are overburdened with political advisors: so-called spads, an ugly and belittling term. But judging by recent performances some belittlement is justified, at least in the Treasury and No.10. There, spads should have been acting as an early-warning system. There is no sign that this happened. It may be that this is unfair: that good advice was proferred and re-proffered until the youngster was told to shut up. Somehow, I do not think so. If I am wrong, then I apologise to the unknown spad. If.

There are also suggestions that having failed to do what they ought to have done, some of these political advisors have been indulging in a briefing war along the lines of: “It was your boss’s fault.” “Rubbish: your boss is to blame.” If so, that is crazy. A modern government can only work if the PM and the Chancellor are as one, at least in public. If youthful aides have been making trouble and inciting some of the sillier Tory backbenchers – no shortage of those – to join in, the grown-ups ought to put a stop to that, right now. It should be made clear that the next time an advisor loses his head, metaphor will instantly become literal truth.(That is exaggerating the degree of literalness. The advisor would not be sent to the Tower. But he should be bin-bagged out of the building.)

Such ruthlessness is essential. After all, the issues at stake in last week’s kerfuffle were relatively minor. Imagine what could happen if – when – there is real difficulty during the Brexit negotiations. Theresa May and Philip Hammond need to sit down for a full and frank discussion, work out what went wrong and resolve that it will never happen again.

Despite recent impressions to the contrary, the PM and her Chancellor both have strong personalities, of a certain type. They both find it easier to command respect rather than affection. In politics, there is nothing wrong with that. But respect depends on competence, especially on the economy. On finance, voters are usually inclined to grant the Tories a reluctant trust. But that can be forfeited, as it was after 1992. Although last week’s events cannot be compared with Black Wednesday and the ERM, damage is done. Moreover, the Conservative party has a recurrent problem. As Michael Portillo once said, it often sounds like the political wing of the Treasury: not a sympathetic stance. That is exacerbated when, as last week, the Treasury’s political wing goes Awol. Did all those involved really think that no-one would notice?

If everyone had been awake, none of this need have happened. A lot of guff is talked about election manifestos. In recent decades, they have been given an elevated status in a specious attempt to deal with an insoluble question. Why should the people obey its government? There is one obvious answer: because otherwise they would be put in prison. But that is hardly the basis for a theory of obligation in a civilised society. There is the myth of the social contract: that our remote ancestors formed a compact with Leviathan in which they exchanged the precarious freedoms of man’s natural condition for security and protection. But even if such an event had occurred – a preposterous idea – why should every subsequent generation be bound by it? The social contract could hardly claim the same divine force as original sin.

There was a time when Tories would have had an answer to all this: the powers that be were ordained of God. In recent centuries, however, the Deity seems to have absented himself from the field of action, rather as the politicos in Nos 10 and 11 did in the run-up to the Budget. There have been attempts to replace vox Dei with vox populi, and to endow democracy with a modern equivalent of divine right. That will not work, for a number of reasons. First, it will never command a sufficient depth of allegiance. Why should a narrow majority based on a plurality of the electorate bind the rest of us, especially given the powers which modern governments have arrogated to themselves?

There was a time when all this was discussed by political philosophers and ignored by everyone else. But in recent decades, the debate has been gradually spreading for the study to the street. From China to Peru, the withdrawal of consent by the governed is alarming the governors and this is likely to continue. Cromwell wanted consent but wondered where he was to find it, In this respect, that brave bad man was being hypocritical. He wanted consent, for what he intended to do anyway (just as Mrs Thatcher believed that everyone should be free, to do what they ought to do).

But Cromwell’s problems with consent were as nothing to those of modern governments. That is why all recent British governments have been reduced to asserting the divine right of the manifesto. Even so, there was no reason for Mr Hammond to hit a rock. This is what he ought to have said. “I do not like raising taxes. Still less do I enjoy reneging on a manifesto commitment. Yet I have reluctantly concluded that both steps are necessary. In an uncertain world, we have to do everything possible to avoid adding to the burden of debt. But there is one point on which we can be certain. The cost of social care has increased, is increasing and will increase further. So I have to raise revenue. On national insurance contributions, the case for discriminating in favour of the self-employed is not as strong as it used to be. I am therefore…”

There would have been protests. But Jeremy Corbyn and Tim Farron as champions of the self-employed? Not much conviction there. The whole matter would now be dying down. It would have helped if the Chancellor had also announced another revenue-enhancing proposal, to reduce the foreign aid budget to 0.5% of GDP rather than 0.7. That would save almost £4 billion a year, and if it also encouraged an efficiency and anti-corruption drive at DfID, the world’s poor need be no worse off.

Anyway, that is for the future. In the short-term, the PM and the Chancellor need to decide which category they fall into. There are two sorts of human beings. There are those who make mistakes. There is a second and much smaller group: those who learn from their mistakes. Let us hope that they firmly resolve to belong to the learners.