When scientific topics become controversial with the public, as with climate change and COVID-19, the public often divides into sides that “question the science” or “trust the science.” It’s important to understand, however, that there is more to these concepts than what can fit on a bumper sticker.

Questioning scientific understanding is fundamentally important to scientific progress. All good scientists are skeptical about everything related to science, especially when it involves their own specialty area of science. But, being skeptical is not the same as rejecting.

The best skeptics think carefully about information and simply place their ideas into three broad categories:

1. Conditionally accept as reasonable;

2. Conditionally reject as unreasonable; and

3. Withhold judgement until more is known.

Scientific experts in a particular field truly understand which ideas fit into which category. They are immersed in the research for years and often for decades, both reading the papers and, even more importantly, doing actual research: They see strengths and weaknesses of arguments on that topic much more clearly than others can. In addition, they go through peer review, the typically humbling process of having other experts judge their work before it can (or can’t) be published.

Who among us is an excellent judge of … everything?

(To the readers yelling at their screens right now because they see themselves as perfectly good judges of everything, you are, respectfully, wrong. And please don’t equate informed judgment with liking or disliking an idea.)

Of course, individual scientists have biases which may affect such decisions, though good scientists try hard to make sure their opinions are driven by evidence and not by factors like politics. It’s not possible for any scientist – or, for that matter, any human being – to be completely objective, and this is why the collective opinion of many experts is more important than the opinion of one.

Political alignment, for example, is a factor that might introduce bias into a scientist’s opinion in fields like climate change and COVID-19. Ideally, the experts span the spectrum of political beliefs and balance out these biases, but typically that is not the case, as shown in a Pew Research Center poll in 2009 which found that most scientists are moderate or liberal. The relatively small percentage of conservatives is concerning.

‘Big picture’ vs. ‘small picture’ ideas and differences

But just as experts should make judgments based on evidence and not politics, the same goes for people criticizing experts. An effective argument that liberal politics is driving climate change research findings, for example, needs to be backed up with strong evidence and not simply with assumptions that correlation implies causality.

An important factor in evaluating the degree of consensus has to do with what can be thought of as the scale of ideas. Experts may virtually all agree on ‘big picture ideas,’ like human actions play an important role in contemporary climate change and wearing masks reduces the spread of COVID-19. At the same time, intense arguments can be taking place on ‘small picture ideas,’ like the accuracy with which we are catching all the effects of clouds within climate models, and precisely how much COVID-19 transmission takes place in different indoor settings.

Another example comes from a controversy getting less public attention these days: evolution. Virtually all professional biologists accept that natural selection drives biological evolution (big picture), but still there are intense debates on just how genes are involved in the changes that happen to a species (small picture).

Public controversies mostly involve big-picture statements, and disagreement on small points is not the same as disagreement on big ones. Of course, all scientific ideas may change, even big-picture ones, but change in big-picture concepts is far less likely than it is in smaller picture concepts.

Government policy decisions, the focus of most public debates on science, should be based on sound science, of course. However, policy demands a broader view. Climate change policy, for example, requires a deep understanding of climate science, but also must involve economic and social ramifications of the various policies. Ideally, experts in each of the three areas generally agree to accept the big-picture idea in their area as “accept as reasonable.” In that situation, climate, economics, and sociology can be weighed to find the best policy to implement. If, as with the case of COVID-19 in 2020, a policy must be implemented before the experts can agree on the ‘reasonable’ category, then policy makers need to consult with a number of experts and develop the best policy under the circumstances. And the public then must be informed that the policy is based on the best current understanding, but may change as new research findings become available. Granted that such public notification is not always easy to implement in the real world.

For a lay person, and for a scientist not specializing in a particular field, “trusting the science” (also phrased as “follow the science” and “the science is real”) involves finding out where the experts collectively put an idea in the three options mentioned above.

As British philosopher Bertrand Russell said it nearly a century ago …

This approach is not a new concept, and the same basic idea was presented in 1928 by British philosopher Bertand Russell:

Even when the experts all agree, they may well be mistaken. Einstein’s view as to the magnitude of deflection of light by gravitation would have been rejected by all experts not many years ago, yet it proved to be right. Nevertheless the opinion of experts, when it is unanimous, must be accepted by non-experts as more likely to be right than the opposite opinion. The scepticism that I advocate amounts only to this:

(1) that when the experts agree, the opposite opinion cannot be held to be certain;

(2) that when they are not agreed, no opinion can be regarded as certain by a non-expert; and

(3) that when they all hold that no sufficient grounds for a positive opinion exist, the ordinary man would do well to suspend his judgment.

These propositions may seem mild, yet, if accepted, they would absolutely revolutionize human life. 

Clearly, we are still grappling with the same problem nearly 100 years later.

Have I given a simplistic overview of a highly complicated reality? Of course. But that’s how we can start to understand something. Learning, like science, is a never-ending process.

Jeffrey A. Lee is a professor in the Department of Geosciences at Texas Tech University. He is the author of The Scientific Endeavor: A Primer on Scientific Principles and Practice (2016).