Where’s the evidence? After years in which respect for science and reason has been in decline, it should be encouraging to hear this question being doggedly asked. And yet the demand for evidence is being used by those sceptical of measures scientists generally support to bring the virus under control: vaccines, lockdowns, masks. Ironically, the scientists’ mantra is now being used against them. How did this happen?
The problem is that while it is well-understood that science is evidence-based, there is not enough understanding of how evidence works. People demand conclusive evidence when strictly speaking there can never be any such thing.
This general shape of the problem has been known to philosophers for centuries. In his wonderfully titled treatise The Lion of Upsetting of all Principles (Tattvopaplava-siha), the 9th-century Indian sceptic Jayari Bhaa pointed out that all knowledge we have of the world is based on experience and as such lacks certainty. It is not just that our senses could be deceived and that witnesses are unreliable. More profoundly, no matter how many experiences of particular cases we have, it takes a logic-defying leap to move from multiple instances to universal principles. David Hume made this problem central to western philosophy nine centuries later.
Scientists accept the impossibility of absolute proof but are not generally too bothered by it. They know that in practice, evidence can be so overwhelming that it in effect settles a matter. You wouldn’t send a rocket to the moon using anything other than Newton’s Laws. Still, it’s easy to forget that the absence of absolute certainty that scientists take for granted can easily trouble those who have come to believe that science provides concrete proofs.
However, even this lesser standard of proof is hard to obtain. It requires repeated experiments with tight control of variables. Little wonder that some of the most robust proofs of cause and effect, such as with smoking and lung cancer, took years to establish. Links between alcohol and health outcomes still remain contested, after years of investigation.
The claims people are demanding strong evidence for now all concern the kinds of things that make such demands impossible to meet.Unless and until thousands of people have taken a vaccine and have been monitored for months if not years, it’s impossible to prove efficacy or rule out bad side effects. Nor is it possible to know for sure how much protection masks offer when laboratory experiments won’t match real-life conditions. As for lockdowns, there are simply too many variables in play to establish for sure that they are effective. You can’t run a double-blind trial on an entire population.
Nonetheless, in all these cases scientists do have good evidence to draw on: well-established general principles. From these they can come to conclusions about which measures are most likely to be effective. With stronger, more direct evidence unavailable, it’s the only way to proceed. In time, they may be shown to be mistaken. As Karl Popper argued, the possibility of being proven wrong is one of the hallmarks of a scientific claim, not a reason to dismiss one.
Take vaccines first. Confidence in their safety and efficacy is based on a combination of strong but necessarily limited evidence about how the specific vaccines have worked in trials, combined with a much larger body of even more robust evidence about how vaccines work in general. In light of the rigorous work completed in some of the world’s best laboratories and the absence of any evidence that the new vaccines are exceptions to well-established general rules, an evidence-based approach would be very confident of their safety and cautiously confident about their efficacy.
Consider that every member of Independent Sage would take the vaccine, the body set up to shadow the government’s own Scientific Advisory Group for Emergencies because there were question marks over its independence.
We also have very good evidence that Covid-19 spreads mainly through small droplets from the nose or mouth. This strongly suggests we should limit close mingling and cover our faces. The fact that we don’t know for sure how well masks work is not an objection, since not wearing them would be contrary to the only evidence we do have.
Questions over the evidence that lockdowns work are the hardest to answer confidently. But again, we do know that close contact is how the virus spreads and so limiting this is clearly the default measure. Many in hospitality object that the virus spreads more in households than in the controlled environments of pubs and restaurants, but you can’t stop people being stupid in their own homes. An inability to shut down the primary areas of infection is no argument for keeping the second-worst locales open.
The fundamental mistake too many make is to demand a level of proof that real-world evidence can’t provide. Their grievance is compounded when they also demand a degree of justice that real-world politics cannot deliver. It is indeed unfair that hospitality closes while people flout the rules by meeting in private homes, and that people in low-risk districts of tier 3 areas face the same restrictions as those in high-risk ones. But making the system perfectly fair requires a degree of control and policing that is unrealistic. Justice in the real world, especially when controlling whole populations, is inevitably imperfect.
You don’t have to have the wisdom of the Buddha to see that a refusal to accept the imperfections of the world is the source of a great deal of dissatisfaction. All governments are muddling through this crisis, some more competently than others but none with 20/20 vision. The doubters may think they are upholding a proud tradition of robust scepticism but the truth is they betray a lack of understanding of the inevitable uncertainties of evidence and realities of fairness.
