Evidence-Based Debunking

debunking handbook

The Debunking Handbook is a very short text by John Cook and Stephan Lewandowsky on evidence-based debunking that was released about a year ago. The general message of the handbook is that debunking is tricker than it seems. If you do it wrong, you can enforce the falsehoods and myths, rather than undermining their influence.

The Debunking Handbook will not provide you with arguments against any specific form of pseudoscience. Rather, it will help you maximize the impact of your own refutations by making them less likely to backfire. This post will examine the tips given in the Debunking Handbook (free to download), then make a few homemade examples of how an evidence-based debunking could look like.


Mentioning a myth creates a sense of familiarity, and familiarity increases the likelihood that people will accept a myth as true. So how do you debunk a myth without spreading it? The key is to put emphasis on the facts, not the myth. Using the myth as a big and bold headline is a huge mistake — people will forget the details of your debunking over time but remember the title, which reinforces the myth. So make readers familiar with the facts, not the myth.


It is important to make the information provided in the debunking easy to follow and understand. The authors phrase it perfectly: “a simple myth is more cognitively attractive than an over-complicated correction”.

Worldview threat

Reading information that goes against your worldview can make your belief in that worldview stronger. This occurs via many different cognitive mechanisms, such as confirmation bias and selective skepticism. Ways to avoid the worldview backfire effect is to include self-affirmation and make use of clever framing techniques.

Filling the gap

Debunking leaves a gap open that must be filled by an alternative narrative consisting of facts in order to be effective. This can consist of an explanation of why the myth is wrong, exposing the tactics of denialists, why the crank promotes that myth, explicit warning that the reader is about to see a myth mentioned and the use of clear graphics.

Here is my stab at a couple of short example using some of the tips from the Debunking Handbook:

Evolution is a well-substantiated scientific explanation for the diversity of life

A massive amount of scientific evidence from areas such as paleontology, genetics, molecular biology, biogeography, biochemistry, embryology converge on the conclusion of evolution. It is a unified explanation for the biological diversity and explains the formation of new species.

A favorite myth promoted by creationists is that the term “theory” means speculation. However, words sometimes have different meanings and in science, a theory is defined as an explanation well-substantiated by the evidence.

Vaccines provide only a very small challenge to the immune system

Vaccines undergo stringent testing before being licensed and are therefore generally very safe. Due to new recombinant technologies, scientists do not need to use the whole organism anymore and so can only pick out the special parts that are important for use in a vaccine. Therefore, even the combination of all vaccines currently given only provide about 200 or so immunological challenges.

A common myth among anti-vaccine advocates is that vaccines overwhelm the immune system. But this is false because even a single bacteria has more immunological challenges (~2000) than all the vaccines given combined and humans are exposed to literally billions of microbes every day since birth.

These examples are by no means perfect. For instance, the second example could benefit from a graph with, say, a pie chart, comparing the immunological challenges from vaccines with that of a single bacterium.

What examples can you come up with?

Emil Karlsson

Debunker of pseudoscience.

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