We’re told these days by our leaders that they’re “following the science” in their handling of the coronavirus pandemic. And, of course, we know what they mean. In an age where it became fashionable not to listen to the experts, they’ve never needed experts more. Briefings abound with flattenings of curves and keeping the R value below 1.

But, if I’m uncharitable enough to unpack the catchphrase, an oddity leaps out.

Politicians and scientists have a different understanding of truth. Politicians want clear answers—should we do this, yes or no? Invoking science should be the gold standard of clarity.

Scientists, on the other hand, deal in uncertainties. Hypotheses are contingent on testing, interpretations are contested, epoch-making claims turn out to be mere statistical blips as more data emerges.

There is so little data as yet on this new virus that “the science” is less a provider of clear yeses and nos than it is a habit of thought.  That habit of thought is the opposite of what the politicians mean—it is a cultivated scepticism, an openness of mind, a willingness to change your mind when the evidence changes.

In the future we’ll know a lot about this virus. But now we don’t know whether people who have recovered generate immunity or whether they can catch it again. We know that it appears to differentially affect men, the elderly and those with underlying health conditions, but we don’t know why some young patients with no known health conditions have a severe response. We think of it is a respiratory illness, but it doesn’t always respond to ventilation in severe cases and it appears to cause kidney problems in some patients. Other patients seem to be overwhelmed by their own immune responses, a so-called cytokine storm. It may not really be a respiratory condition at all.

We don’t think the virus is mutating in the way the influenza does, but we’re not sure. We don’t even know for sure yet what the death rate is.

Not being sure is “following the science”, but this doesn’t cohere well with policy-making. And we want simple clear answers. This is understandable in a population where scientific literacy is low. We’re only just getting used to weather forecasts that give us probabilities of rainfall rather than simple yes-no predictions. But, perhaps we’ll use this crisis to become more comfortable with uncertainty and more conscious of which things we can be certain about.

Angela Merkel, in a broadcast to the German nation, gave a detailed epidemiological explanation of what different values of R meant for the health system. Covid 19 is thought to have an R of between 2 and 3. This means, without intervention, every infected person goes on to infect between two and three others. If measures like social distancing keep R below 1, the chain of transmission starts to be broken. Merkel explained what a small increase in R meant: if it goes up to 1.1, the German health system would be overrun by October; at 1.2, the crisis would come in July, and at 1.3, by June.

Even where there is a certainty within a discipline, building a response to the pandemic involves different disciplines with different answers. An obvious example is the answer to the question “how long does the lockdown need to last for?” Epidemiology says the best answer is as long as there are high levels of the virus circulating in the population. But behavioural science tells us that people will only tolerate being cooped up for so long before they begin to go walk-about. There were already some signs in the fifth week of the British lockdown that this was starting to happen.

So, from an epidemiological point of view, the lockdown on 23 March came late. But from a behavioural viewpoint, this may have been the optimal time. And, of course, other factors have to be considered too, most particularly the effect on the economy, on people’s livelihoods and consequently on their mental and physical health, covid 19 notwithstanding. We won’t know until the official papers are released, but there are speculations that there was a policy debate in the UK in March as to whether to bear down on the spread of the virus or, alternatively, whether to let infections rip hoping for a quick peak and the creation of “herd immunity”. The world has never encountered anything like this, not even in the Spanish Flu pandemic of 1918-19, because there was no lockdown then. On the contrary, the First World War ground on towards its grisly conclusion despite the virus.

So there really is no simple “science” that can be followed. It’s all a matter of balancing some things that are known and guessing at some things that are not yet known. The decisions are ultimately political, not scientific. The “following the science” mantra may simply serve to shift blame onto the scientists if things go wrong.