Evidence can only map the terrain – but without it we are lost
4 min read
At the end of his report on the Challenger shuttle disaster, Richard Feynman wrote that NASA owed it to the citizens that funded it to be “frank, honest, and informative, so that these citizens can make the wisest decisions for the use of their limited resources”.
For NASA, one might read any public body. Because the problems that led to Challenger’s failure – top-down political pressures that ignored the evidence known by those ‘on the ground’ – are not confined to space launches. As Feynman said, people “fooled themselves” that evidence – which would otherwise cause a launch to be cancelled – couldn’t stand in the way of high-profile plans. For launch after launch they got away with it. But we all know the end result, because, as Feynman said: “Reality must take precedence over public relations, for nature cannot be fooled.”
The idea that ignoring inconvenient evidence can make the problem it indicates go away is always tempting. As President Trump said during Covid: “If you don’t test, you don’t have any cases. If we stopped testing right now, we’d have very few cases, if any.”
But are we just as guilty in Parliament? I applied to become a crossbench peer after hearing Baroness Bennett of the Greens on the radio commenting that the House of Lords needed more people in it who could deal with and communicate scientific evidence. That had been the basis of my whole career – as a documentary-maker at the BBC and then at Cambridge University running the Winton Centre for Risk and Evidence Communication.
Following our motto of “to inform and not persuade”, we at the Winton Centre worked on how to present evidence in a way that allowed people to understand what was known about a topic, and what was not known, and to combine that with their own values and principles to make their own decision.
This is often seen as a revolutionary concept. Once I was talking to a group of civil servants about how to communicate uncertainties so that decision-makers knew how much weight they should put on each piece of evidence. One official asked how to respond to a boss who’d suggested he “talk to fewer experts – ideally just one” as a way to narrow down the uncertainties. Trumpian logic alive and well in Whitehall.
Presenting evidence clearly whilst speaking in Parliament is certainly a new challenge. I know from my academic research (and my own experience) that numbers are very hard to compare and interpret properly without ‘seeing’ them – ideally graphically. It’s easy enough to throw a ‘powerful’ statistic into a speech, and my decades of making television programmes help deliver a script that persuades its audience. But my subsequent years of ‘informing not persuading’ now make me acutely sensitive to that method.
Every policy decision has the potential to benefit some people and harm or cost others. I want to see the evidence on what those benefits and harms might be, to whom, with what levels of certainty. I want to see how different policy options might alter these, and the practicalities of implementing different policies. Then, separately, I want to hear the moral and value-led arguments on how different people weigh that evidence. Because we do all weigh things differently.
Evidence doesn’t ‘tell you’ what the policy should be. It doesn’t provide a map that shows you where to go. You can’t ‘follow the science’. Evidence provides a map of the landscape, which helps you see how to get to the end point you choose to go to.
Anyone arguing for one policy over another can make their case for a different destination: why they think a particular cost outweighs a particular benefit or vice versa. Or they can argue over the evidence itself. But trying to blur evidence with a fog of uncertainty, cherry picking facts to cite to support your argument, using it as a tool to persuade? You might fool your opponents – even yourself – and win your argument. But nature is not fooled by rhetoric, and one of the risks you tried to ignore will, eventually, manifest itself.
