Experts with opinions and experts with facts

Photo by Markus Spiske on Unsplash

I have muted the words “coronavirus” and “Covid-19” on Twitter. I hardly see any tweets about the coronavirus epidemic anymore. I would like to stay informed but felt that Twitter was no longer the right medium for that. The line between knowledge and opinion had blurred. I could no longer judge which information I should trust and which I shouldn’t. One scientist tweets that the number of infections is increasing exponentially, the other writes it isn’t. One thinks government measures are going too far, the other not far enough. All experts, but not in this area.

My class on critical thinking last week was about experts and expertise. “Who do you think is an expert on the coronavirus epidemic?” I asked the students of the bachelor’s program in human health. “The epidemiologist?” The first hesitated. The lesson couldn’t get a better start. “I am an epidemiologist,” I replied, “but I know almost nothing about epidemics.”

Expertise is subjective
An expert is someone with extensive knowledge and experience in a specific subject or area. Someone recognized by others for their expertise. An authority. Should someone be a professor or doctor? How many years of experience should someone have? There are no criteria for who is an expert in a particular subject or area. The assessment of expertise is subjective and relative. Someone is an expert, especially when others think they are.

Expertise has limits. An expert specializes in a particular subject, often at the interface of several disciplines. This means that an expert is also well informed on a broader range of topics. My specialization is in the field of predictive DNA tests for complex diseases, such as cardiovascular disease and diabetes. I understand prediction, DNA, testing, and the risk factors for complex diseases, but that does not mean that my expertise covers all those subjects. I may know more about these subjects than the average citizen, but my knowledge on these topics comes with doubts. I can assume that my understanding is correct, but then I am ignoring the limits of my expertise. Someone is an expert on a specific topic, but not outside of it.

So what experts say falls into two categories: topics they know about and topics they don’t know. It is crucial to keep those two apart. When experts talk about topics they know about, they talk based on knowledge and skills. They examine the relevant facts and research results, subject them to a critical evaluation, and then come to a conclusion. They can explain what those facts and results are, why they are important, and how they led to that conclusion.

When experts talk about topics they don’t understand, they are, just like everyone else, people with an opinion, intentions, and interests; but also with prejudices, lack of knowledge, and faltering introspection. People who say things they have heard somewhere. Let’s say, ordinary people like you and me.

On social media, it is not always clear whether an expert sends a fact or an opinion into the world. A tweet with a photo of their dog leaves no doubt, but serious messages are confusing and potentially misleading. After all, scientists are followed on social media because of their expertise. How should followers know which of their posts rely on their expertise? How should they know, for example, that “Wash your hands often” is expert advice if CDC tweets that, but not when I share it, as an epidemiologist?

It is even more confusing if scientists without relevant expertise start discussing expert advice. I was guilty of this myself this week. A colleague wrote that there was sufficient reason to cancel meetings, and I asked what scientists know about the effectiveness of self-isolation. Perhaps a legitimate question, but the timing was misplaced. CDC, ministries and other authorities know that they must take far-reaching measures about unclear future scenarios based on unreliable and scarce data. They know that the effectiveness of the measures is not 100 percent certain, but they cannot afford to wait for research first. Did I really have to ask that question? Was anything going to change with the answer? (no)

Expertise has limits. When scientists make statements in the field of my expertise, I immediately see who understands it, who is misinformed but could understand it, and who misses the mark. Such statements leave an impression of the quality and rigor of their work. I anticipate that experts look at non-expert statements similarly. Making statements about topics that you do not understand is not only meaningless, but it — perhaps unjustly — may question your expertise.

A version of this article first appeared in Dutch in the NRC Handelsblad on March 14, 2020.

Professor of epidemiology | Emory University, Atlanta USA | Writes about (genetic) prediction, critical thinking, evidence, and lack thereof.

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