What forensic science can teach people about healthy scepticism

How can you navigate a world full of outlandish claims? Shutterstock

Scepticism has a bad reputation. Sceptics are considered to be a grumpy bunch who automatically distrust anything and everything. But as any forensic scientist can tell you, it’s a very valuable approach to everyday situations– especially in a world where people are constantly being bombarded with information.

Every day we’re presented with “miracle cures” and “wonder diets”. Conspiracy theories and urban myths abound. We’re told that “superfoods” can change our lives. We’re assured that the appliances in our homes are perfectly safe. All of these claims are accompanied by what’s referred to as “evidence”. But how often do we critically interrogate this evidence?

I’m a trained forensic pathologist and teach the subject at a South African university. Some of the things that our students learn can be applied to help navigate those fantastic claims leaping out at you from pharmacy shelves, Facebook pages and in grocery stores.

How forensic scientists think

Most scientists, when approached with a claim that sounds too good to be true, will respond: “That’s nice – let’s prove it!” Forensic scientists, though, will reply: “That’s nice – let’s disprove it!” That’s the way we’re trained to think.

Our work entails asking many questions and looking at all of the available data. Two famous sceptics who applied forensic thinking to their work, Michael Shermer and Carl Sagan, came up with a list of basic questions that can be asked to get to the heart of the validity of any fantastic claim. Sagan was a world renowned professor of astronomy and director of the Laboratory for Planetary Studies at Cornell University. He was also a consultant and adviser to NASA. Shermer is a science writer, science historian and the publisher of Skeptic magazine.

  1. How reliable is the source of the claim?

  2. Does this source often make similar claims?

  3. Have the claims been verified by another source?

  4. How does the claim fit with what we know about how the world works?

  5. Has anyone gone out of the way to disprove the claim, or has only supportive evidence been sought?

  6. Does the preponderance of evidence point to the claimant’s conclusion or to a different one?

  7. Is the claimant employing the accepted rules of reason and tools of research, or have these been abandoned in favour of others that lead to the desired conclusion?

  8. Is the claimant providing an explanation for the observed phenomena or merely denying the existing explanation?

  9. If the claimant proffers a new explanation, does it account for as many phenomena as the old explanation did?

  10. Do the claimant’s personal beliefs and biases drive the conclusions, or vice versa?

How to think like a sceptic.

Scepticism in action

I saw this sort of questioning in action while attending a coroner court hearing in Britain. A man had hit a woman with his car. She then developed deep venous thrombosis – a blood clot – in her legs, which broke off and travelled to her lungs, causing a pulmonary embolism. She died.

At the hearing, the man was asked why he thought he’d collided with the woman. He explained that he’d been blinded by sunlight and hadn’t even seen her. The forensic scientists involved in the case put his story through rigorous tests. They confirmed that the sun was blinding at that particular time of year at that particular intersection and at 4pm specifically – which was when the crash had happened. All of the questions Sagan and Shermer outlined were applied and lots of data was gathered.

The magistrate ordered that a billboard be erected near that intersection so that the sunlight wouldn’t blind drivers at 4pm at that time of year.

The man’s claims were treated with scepticism and carefully assessed. It was solved with what medical practitioners call a “P4 approach”: predictive, preventative, participatory and personalised. In this case, it would prevent the same kind of accident from happening again. This is one of the most valuable aspects of forensic, sceptical thinking. If you carefully analyse claims and sift through the available evidence, you can make educated choices that can save time, money – and even lives – later on. This is the feedback system that all societies need.

Empowering people

This sort of thinking can be applied in many situations. In large parts of the developing world, primus stoves cause hundreds of deaths and many more injuries, almost every winter. Imagine if communities were equipped with the sort of forensic, sceptical tools I’ve described in this article? They’d be better able to assess which sorts of stoves are safe and which aren’t, and to demand improvements from the manufacturers. They wouldn’t be forced to take manufacturers’ or retailers’ claims at face value.

Forensic thinking and healthy scepticism can help us all to navigate the world much more thoughtfully – and safely.