How can we know what is true?

True or False

Science denialists believe the opposite of scientists.

Science shows that vaccines are safe and effective; anti-vaxxers believe they’re neither.
Science shows that the earth’s climate is changing as a result of human activity; climate denialists either claim it isn’t changing or the change is not the result of humans.
Science shows COVID-19 is a coronavirus that causes serious illness; denialists either deny its existence or its severity.

Determining scientific truth requires being willing to change conclusions based on new evidence.

How we do we know what is true?

It’s NOT, as many denialists think, by deciding WHO to believe. You can’t determine scientific truth merely by deciding that Donald Trump knows more science than Dr. Tony Fauci.

It’s NOT even, as other denialist think, by deciding WHAT to believe. You can’t determine scientific truth by deciding that YouTube videos present a more compelling case for a particular belief than scientific papers.

Rather, scientific truth is determined by HOW to believe.

Science is a process.

As the authors explain in Enquiry and Normative Deviance; The Role of Fake News in Science Denialism:

Science denialism doesn’t merely involve a rejection of a scientific theory — otherwise scientists themselves would count as science deniers given that they would reject theories on the basis of their explanatorily inadequacy. Rather, science denialism deeply challenges the practice [of] impartially testing research methods, theories, and evidential sources with the aim of improving the accuracy of scientific theories.

That’s because science isn’t about specific beliefs; it’s about evidence and how we use it. Simply put, science requires two things:

First, determining scientific truth requires following all available evidence to logical conclusions.

That’s why science denialists hold beliefs that are inevitably false:

Instead of attempting to find ALL available evidence, denialists use only evidence that is offered to them by other denialists.

Instead of assessing ALL evidence, denialists assess only some, carefully cherry-picked pieces of data.

Instead of incorporating the MOST sophisticated scientific evidence (by reading and understanding scientific papers) denialists rely overwhelmingly on the LEAST sophisticated forms of data that can be easily transmitted in bite sized amounts by web pages and YouTube videos.

Second, and even more importantly, determining scientific truth requires changing conclusions based on new evidence.

What does that mean in practice?

It means acknowledging the LIMITATIONS of the existing data.

Scientific papers usually contain a section near the end that explicitly acknowledges that the existing data might have led to erroneous conclusions perhaps because not enough data was collected or because the data was inadvertently collected from a non-representative sample.

It means interrogating your own conclusions for ALTERNATIVE explanations.

In the same section of the scientific paper acknowledging the limitations of the existing data, there is usually a few sentences or a paragraph entertaining alternative explanations for the existing data and making a case for why those alternative explanations are not supported by the data.

It means acknowledging that the conclusion may change and SHOULD change if future data contradicts it.

Lay people often point to changes in scientific belief as if they reflect a weakness of science. But the willingness to follow additional evidence to a new (even an opposite conclusion) is the great STRENGTH of science.

It means testing to see if you are wrong by considering, reading and attending scientific meetings with those who disagree.

Scientific truth can only be found in contentious communities that deeply engage those with whom they disagree. Denialism, in contrast, takes place in supportive communities (information silos) that drastically limit the data available, misrepresent those who disagree and never, ever directly engage with them publicly.

In other words, the ONLY way you can tell whether a scientific claim is true is by having it compete with other claims on a level playing field and being willing to accept the outcome if it loses.

Science encourages that kind of competition. Denialism fears it.