Justice secretary Robert Buckland last week blamed the public for England’s new lockdown.
In particular, the fault was with people failing to self-isolate properly.
Of course, in a purely technical sense Buckland is right.
The virus spreads by contact with an infected person. If people do not self-isolate, Covid-19 will continue to percolate across the population.
But this is to miss the point. The real question is: why have people been so cavalier about following the regulations in recent months?
Back in March and April, lockdown rules were widely observed more or less to the letter. At first, regulations which banned crowds at sporting events and closed pubs were accepted as being reasonable. Later, the entire nation accepted the government’s message to stay at home except in extremely limited circumstances.
However, as the summer unfolded, the authorities began to give a more mixed message.
Tens of thousands took part, for example, in Black Lives Matter marches. The police, far from dispersing these events, appeared to offer support.
A reasonable inference to draw was that the authorities did not really believe that mass outdoor gatherings spread Covid in any serious way. The official line of the various UK governments, however, continued to be that the virus remained a major threat.
This kind of public information obviously plays a part when people decide what course of action to follow in terms of, say, self-isolation or not visiting crowded bars. But each person also has information which is private to that individual, or at most shared by a few close family and friends.
Many people, for example, visited crowded beaches and did not seem to catch Covid. And in their immediate circle, most of those who did catch the virus experienced no real problems. It was not the killer the government scientists warned it was.
Over time, the public has gradually come to place more weight on their own private information, and less on the set of public information provided by the government.
To the scientists on SAGE, this appears to be wholly irrational. Private information by definition is only partial. Public information gives a more complete and hence more accurate picture.
But it can be entirely rational for a person not to just to give increasing weight to one of these, but to come to rely exclusively on either private or public information.
A famous 1992 paper in the Journal of Political Economy by Sushil Bikhchandani and colleagues of the University of California explains why.
A key driver of the change is the relative weights which other people use. The more the people you know rely on their own information rather than that put out by the government, the more rational it is for you to do the same.
The California economists coined the phrase “information cascade” to describe this process.
The UK government allowed doubts to creep in about the reliability of its information. Mass gatherings were a Bad Thing, but the police did nothing to stop them. As such, the information they are giving out now about the importance of self-isolation is being viewed with scepticism.
It was not inevitable that the public message would be undermined. But thanks to other communication debacles (the wildly misleading Whitty-Valance charts, for example), momentum is now firmly moving against government messaging.
Such a trend can only be reversed by drastic action. The justice secretary should look close to home for the culprits of our current predicament. Sacking some prominent scientific advisers could get the “information cascade” flowing back in the government’s direction.