Last month, the official group of scientific advisers — SAGE — warned the government that only a quarter of those who need to self-isolate due to coronavirus symptoms were in fact doing so.
This illustrates a concept which is of great practical importance: namely the conflict between individual and collective rationality.
Consider Margaret Ferrier, an SNP MP (who has since had the whip removed) who travelled by train from London to Scotland despite knowing she had tested positive for Covid-19. Better for her personally to be at home in Glasgow than stuck in a London hotel for a week, but worse for society as a whole as she risked spreading the virus to everyone on the train with her.
The textbook model of economics neatly sidesteps this potential problem. It sets up an idealised situation in which there is no conflict between individual and collective rationality. The task is then to discover what assumptions about behaviour are needed to be compatible with such an outcome.
It is a very challenging question, and several of the early Nobel Prizes in economics were awarded for work in this area.
Economics itself has moved on in recent decades and pays much more attention to the potential rift between what is good for the individual and what is good for society.
One of the most influential thinkers in this area is Elinor Ostrom who received the Nobel prize in economics only three years before her death in 2012. Her work is very relevant in the Covid crisis.
Her doctoral dissertation was on how farmers and others in Southern California solved the problem of water management in their local area. For individuals with favourable locations, it was rational to grab as much water as they could. But collectively, this was a bad outcome. Others would be short of water.
The key feature of Ostrom’s work was to show that individuals were capable by their own actions of avoiding conflicts of individual and collective rationality. It was not necessary to have a heavy-handed regulator trying to impose a solution from above.
Like the Nobel laureates before her, she basically worked out what assumptions were needed for this to happen.
An essential element is that those involved must have some feeling of being part of a group. Further, disruptive and self-serving behaviour should be speedily identified and punished, in ways which are seen to be fair within the group. People also need to feel a sense of ownership of any restrictions which are asked of them.
When Boris Johnson announced lockdown on 23 March, in effect the nation was the group. For a period, most people behaved with proper regard to others.
The subsequent maze of complex and often contradictory diktats issued by health bureaucrats and politicians since then has eroded much of this trust.
Countries such as Germany which had locally based Covid strategies from the outset have fared much better than the centrally planned attempts in the UK, in part because they have been able to maintain this trust and sense of community.
At long last, the UK government shows signs of being willing to trust local authorities to do what is best for their area — in the form of local lockdown rules. They may still get it wrong, but local autonomy on Covid policy at least gives the chance of restoring the trust which is essential to any successful strategy.