In his 1933 inaugural address, US President Franklin D Roosevelt tried to reassure a country in the depths of the Depression that “the only thing we have to fear is fear itself”. Roosevelt argued fear would paralyse efforts to revive the US economy.

This week, Joe Biden took the opposite tack, warning we face a long, dark pandemic winter. According to models run by Joshua Epstein, an epidemiologist at New York University, the president-elect did the right thing. In this case, ginning up the right level of fear is as important in fighting the virus as the Covid-19 task force he has appointed. 

Fear is a powerful motivator, Professor Epstein says, so setting expectations and managing behaviour is absolutely critical to containing the virus. Traditional economic models are based on the idea that rational actors weigh the costs and benefits of their decisions and optimise the outcome. But such rational actors don’t really exist. In his work, Prof Epstein offers an alternative. The individuals in his models are programmed to feel fear, respond to it and spread it through their social networks.