A key maths tool during the pandemic came about because of an 18th-century debate about Christianity. The lesson we can draw today is that moral philosophy matters
Do the laws of science and mathematics explain everything, without any need to bring God into it? The pious once believed that wrathful deities could unleash plagues. As reason emerged in the temple of thinking, there was a move to claim God was behind the advance of reason. In this struggle between beliefs, new pathways of thought emerged, to the benefit of humanity.
The fruits of this theological and scientific collision have been revealed during Covid. The work of Thomas Bayes, an 18th-century clergyman and mathematician, has become central to understanding the pandemic. Bayes’ theorem shows how to calculate the accuracy of lateral flow tests used to map the spread of coronavirus. The maths is used to work out the conditional probability that a person is not infected, given a positive test. This is just the tip of the Bayesian spear. David Spiegelhalter and Anthony Masters wrote in April that many complex pandemic analyses “have been ‘Bayesian’, including modelling lockdown effects, the ONS infection survey, and Pfizer-BioNTech’s vaccine trial”.
