There is a point at which stupidity ceases to be a merely intellectual error and becomes a crime. If Nick Cohen is right, the government has crossed this point. He writes:

[David] Davis seems closer in spirit to a bubbly PR girl than a hard-headed statesman. He wants to hear only good news. He wants to see only smiling faces...On no account must businessmen and women say they are worried about Britain abandoning its membership of the single market, the civil servants warn. They needed to 'go into the meeting saying that they were very excited by the possibilities of Brexit. Anyone who felt differently tended to be asked to leave in the first five minutes.

This echoes Ian Dunt:

We are living under rulers who do not believe, or at least refuse to trade in, objective fact. Reality is a barrier to the successful implementation of Brexit and must therefore be ignored.

Now, I have a dim view of this government but even I struggle to believe these accusations simply because they are so outrageous - though I fear that the "have cake and it it" memo corroborates them.

I say this because we know that top decision-makers can be prone to at least five cognitive errors*. These are: overconfidence; wishful thinking; the confirmation bias; the planning fallacy; and the tendency to become detached from the reality of what's happened on the ground. Any good decision-maker should bend over backwards to avoid these obvious errors. If Nick and Ian are remotely correct, however, our government is doing the precise opposite; it is creating a climate in which these errors are actually encouraged.

In an uncertain world, it is impossible to take the best possible course of action. We should, however, be able to avoid the most egregious errors. The Tories seem however to be cultivating them.

This is unforgivable.

For one thing, these errors have been well-known for years. Kenneth Boulding warned (pdf) back in 1965 of the danger of decision-makers "operating in purely imaginary worlds". And the research on cognitive biases dates back at least as far as the 1970s and should by now be well-known to anyone who has even a passing interest in the social sciences.

But even if ministers are pig-ignorant of intellectual history - which itself is unacceptable - they should at least be aware of the Chilcot report. It showed that the decision to go to war in Iraq was based in part upon errors such as wishful thinking and the confirmation bias. And it warned that positive thinking "can prevent ground truth from reaching senior ears".

Success - or even basic competence - requires that we learn from mistakes. This government, however, seems to be doing the opposite. Instead of learning Chilcot's lessons, it seems desperate to repeat them.

All this poses two questions. One is: how can people who supported Brexit for years or even decades be so appalling prepared for the process of doing so?

But there's a bigger question. The point of being a government minister is that you must take decisions. You should therefore at least know how to avoid the worst ones, and be acquainted with the basics of decision theory. But the government seems to fail even in this. Which poses the question: why the hell do they want power if they are unwilling to exercise it with even minimal competence?

* Of course, there are many more. I'm confining myself to those that seem most relevant for now.