Don’t believe what you think!


Edzard Ernst
Edzard Ernst
Edzard Ernst is Emeritus Professor of Complementary Medicine at the Peninsula School of Medicine, University of Exeter. He is the author of ten books on complementary and alternative medicine.

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What follows is a slightly modified and abbreviated version of the introduction to Professor Edzard Ernst’s recently published book, Don’t Believe What You Think.

Why do even intelligent, well-educated people so often draw wrong conclusions about so-called alternative medicine (SCAM)? The main reasons, I submit, are misinformation, motivated ignorance, motivated reasoning, confirmation bias, and denialism.

Misinformation overload

The popular press has an insatiable appetite for SCAM. There are currently some 50 million websites on the topic. This amount is extraordinary; no other medical subject comes even remotely close. Amazon UK lists currently over 50,000 books of SCAM. This figure dwarfs the numbers of books on most other medical subjects – gynaecology: 10,000, orthopaedics: 10,000, rheumatology: 4,000, for instance. These numbers become even more impressive, once we realise that the vast majority of all SCAM books are written for a lay readership, while most of the books on other medical topics are for healthcare professionals. It is clear from these data: consumers are currently bombarded with information about SCAM.

news paper with the word truth in large writing

But such an abundance of material is not necessarily a bad thing. What makes this plethora of information worrying is the fact that the information includes an opulence of falsehoods. SCAM has been an industry of ‘fake news’ and ‘post truths’ long before these terms even entered our vocabulary. Crucially, most SCAM proponents seem to be unwilling or unable to differentiate between reliable and unreliable sources of information; those that agree with their preconceived ideas tend to be viewed as reliable, and those that don’t are dismissed as unreliable.

Some 15 years ago, my team systematically investigated this ‘industry of untruths’ by extracting from 7 best-selling SCAM books the number of treatments being recommended for given diseases. The results were staggering; every SCAM seemed to be recommended for every condition regardless of any common sense or scientific evidence. In fact, for most of the recommendations, the evidence was either non-existent or outright negative. Even worse, there was no agreement between the 7 books indicating that the recommendations were entirely random. Here are a few examples (the numbers in brackets refer to the number of different SCAMs recommended for that condition):

  • Addictions (120)
  • Arthritis (131)
  • Asthma (119)
  • Cancer (133)
  • Depression (87)
  • Diabetes (89)
  • Hypertension (95)

When we evaluated the content of SCAM websites for certain diseases, such as cancer, our findings revealed that most sites recommended for an abundance of treatments not supported by sound evidence. The potential for patients to get harmed by these books was undeniable. We concluded that “the most popular websites on SCAM for cancer offer information of extremely variable quality. Many endorse unproven therapies, and some are outright dangerous.

We also assessed the content of the websites of 200 chiropractors. Our findings showed that 95% of these sites made unsubstantiated claims. We concluded that “the majority of chiropractors and their associations in the English-speaking world seem to make therapeutic claims that are not supported by sound evidence”.

But this bombardment of consumers with misinformation is not just confined to the written word. When the falsehoods come directly from the mouth of a SCAM enthusiast, they get even more dangerous. SCAM practitioners issue wrong advice to their patients all the time, and the same sadly applies to many pharmacists. Another of our investigations determined what advice health food store employees present to individuals seeking treatment options for breast cancer. Eight researchers asked employees of all health food stores in a major Canadian city what they would recommend for a patient with breast cancer. Thirty-four stores were examined, and a total of 33 different products were recommended. Crucially, none of these products were supported by good evidence of efficacy.

Many consumers will readily accept the false information as true. Others might initially have some doubts but will eventually yield to the constant onslaught. The plenitude of cleverly marketed untruths acts like a brainwash and is unquestionably a prime reason for consumers’ erroneous beliefs about SCAM.

Motivated ignorance

A stethoscope on a table

Motivated ignorance is a lack of knowledge due to a conscious decision to ignore information that, for some reason or other, is inconvenient, disturbing or unwelcome. The phenomenon is very common and affects us all. A classic example of motivated ignorance is the person who feels unwell but does not consult a doctor because she is afraid of a serious diagnosis; she thus makes the conscious decision to remain ignorant about her health.

Motivated ignorance has been studied extensively. In one investigation, for instance, volunteers were given the choice of reading either a pro or a contra article on the topic of gay marriage. Those who chose to read the opinion they agreed with would be given a chance to win $7, while those who chose to read the opinion they disagree with would have the chance to win $10. The results showed that 63% of the volunteers opted for motivated ignorance and chose not to read the opinion they disagreed with thus preferring to forfeit the chance to win more money.

We all regularly succumb to motivated ignorance, if we want to avoid disconcerting information. Such avoidance of knowledge occurs particularly in the area of healthcare. In SCAM, it is an important reason for people to shut their eyes and ears to the uncomfortable reality that their favourite SCAM might be not as fabulous as they think. The phenomenon is especially powerful when someone has acquired a quasi-religious belief in SCAM. On my blog, I often receive comments from such believers. Whenever they are confronted with the evidence that their SCAM might not be as beneficial as they had assumed, they deny the validity of this information. They might state, for instance, that they reject the evidence because they assume:

  • the evidence is fabricated,
  • the research is paid for by ‘Big Pharma’,
  • the study is fatally flawed.

It is hard to convince a religious person that her god does not exist. In my experience, it is equally difficult to convince SCAM-believers that their SCAM is bogus, and even harder perhaps that their guru is a charlatan. In fact, in many instances, this proves to be impossible. For people who are bent on rejecting science, even the most persuasive evidence will have little impact. In the extreme, motivated ignorance can kill the person who is afflicted by it; think, for instance, of patients refusing life-saving therapy and preferring to opt for an ineffective SCAM despite overwhelming evidence that the conventional treatment would save their lives.

Motivated reasoning

Motivated reasoning goes one crucial step further than motivated ignorance by consciously defending a treasured belief regardless of even the most compelling evidence against it. The two phenomena are paired like twins and usually affect us simultaneously. Motivated reasoning uses a range of techniques aimed at defending indefensible positions, e.g :

  • inventing untruths,
  • abandoning logic,
  • cherry-picking the evidence,
  • discrediting opponents.

Motivated reasoning can be seen as an attempt to avoid cognitive dissonance – the mental discomfort we experience when faced with contradictory beliefs – frequently at the expense of integrity and sometimes even honesty. Yet, motivated reasoning is common and few of us are immune to it. In SCAM, it is applied abundantly both by individuals as well as organisations, and there are countless examples to demonstrate it.Motivated reasoning is not merely distorting the views of SCAM providers and their patients, it also has the potential to endanger public health.

Confirmation bias

Confirmation bias describes our preference for information that is in line with our prior beliefs. For explaining why consumers often believe in falsehoods about SCAM, it probably is, next to misinformation overload (see above), the most important phenomenon.

While motivated reasoning and motivated ignorance are largely based on our conscious decisions, confirmation bias occurs without us even noticing it. It functions like a filter that eliminates disagreeable information and selectively allows material to enter our mind that agrees with our views. Thus, we subconsciously focus on information that confirms our opinion, while rejecting data that contradict it.

The effects of confirmation bias can be profound and alarming: we might pride ourselves of having an open mind and to fairly consider all the available evidence, while our preconceived beliefs continuously eliminate much of the information that would otherwise contradict them. In the end, we might feel entirely confident to be well-informed and correct, while we might, in fact, be totally misinformed and wrong.

An open book with glasses resting on the page

The best protection from falling victim to confirmation bias is to systematically follow where robust science leads us. The criterion must be the reliability of the science, not the direction of its results. Avoiding being influenced by confirmation bias can be a big ask indeed. It often requires not merely accessing the scientific literature but also differentiating between rigorous science, poor science, pseudoscience and fake science.

Patients, particularly those suffering from serious conditions, want the benefit of their pet therapy to be true, and thus it becomes true. They filter out unwelcome information and what remains is a positive impression.


In extreme cases, confirmation bias can degenerate into a complete denial of the truth. An apt example of science denial is SCAM providers’ prevalent negation of the benefit of immunisations. The evidence that vaccinations generate much more good than harm is truly overwhelming. Yet, in the realm of SCAM, many enthusiasts deny this well-documented, undeniable fact.

Science denial is defined as dismissal of established scientific evidence for irrational reasons. Even though they sometimes get confused, denialism is fundamentally different from scepticism. In some ways, it is even the exact opposite. Scepticism is based on rational analysis, scientific information, theoretical predictions and empirical evidence. By contrast, science denial is irrational and disregards scientific information and evidence, even in the face of overwhelming data.  

Science denial can be naively innocent and inconsequential, for example, in the case of members of the flat earth society. However, in many instances, it causes considerable harm. The denial of the benefits of immunisations, for instance, has brought back measles epidemics and caused the death of hundreds of children. The South African AIDS denialists claimed that AIDS was caused not by the HIV-virus but by poverty-induced malnutrition, recommended nutritional treatments for AIDS and banned the use of antiretroviral drugs. This prompted around 171,000 HIV infections which caused ~343,000 deaths between 1999 and 2007.

Science denial is often paired with conspiratorial thinking which can be viewed as critical thinking gone badly wrong. Conspiration theorists tend to explain certain events as a result of secret machinations of powerful, dark forces. Thus, anti-vacationists as well as AIDS denialists tend to believe that the pharmaceutical industry is conspiring against the public in order to make money at the cost of our health.

The words "fake news" typed on a typewriter

In a similar vein, some SCAM proponents believe that their SCAM is suppressed by the powerful interests of the establishment. A study from the US, for example, found that belief in conspiracy theories is rife in the realm of SCAM. The investigators presented people with 6 different conspiracy theories, and the one that was most widely believed was the following: THE FOOD AND DRUG ADMINISTRATION IS DELIBERATELY PREVENTING THE PUBLIC FROM GETTING NATURAL CURES FOR CANCER AND OTHER DISEASES BECAUSE OF PRESSURE FROM DRUG COMPANIES. A total of 37% agreed with this statement, 31% had no opinion on the matter, and 32% disagreed. What is more, the belief in this particular conspiracy correlated positively with the usage of SCAM. Such findings imply that the current popularity of SCAM is at least partly driven by the conviction that there is a sinister plot by ‘the establishment’ that prevents people from benefiting from SCAM.

Perhaps the most tragic examples of the damage caused by confirmation bias combined with science denial and conspiratorial thinking are those of parents preventing their own children from receiving life-saving treatments.

The three-year old Noah was diagnosed with acute lymphoblastic leukaemia, a blood cancer with a very good prognosis when treated (~85% of all children affected can be completely cured and expect to live a normal life). The child was admitted to hospital and, initially, chemotherapy was started. But the treatment was not finished, because the parents took their child home prematurely. The mother, a 22-year-old ‘holistic birth attendant’, had been against conventional treatments from the start. She nevertheless agreed to the first two rounds of chemotherapy “because they can get a medical court order to force you to do it anyways for a child with his diagnosis”. Then she absconded and treated her son with several forms of SCAM: rosemary, colloidal silver, reishi mushroom tea, and apricot seeds.

In a matter of hours, they were found by the police. Noah was then taken from his parents to be medically treated. The parents, meanwhile, were being investigated on suspicion of child neglect. They insisted that they were merely trying to give their son alternative medical care, accusing the police and medical officials of stripping them of the right to choose their own treatment plan for their son. Their supporters called the state’s decision to take custody of Noah a “medical kidnapping”. 

Another article reported an even more dramatic case:

The parents of a seven-year-old boy who died after they decided to treat his otitis with homeopathy were convicted of manslaughter. Francesco, from Cagli near Pesaro, died on May 27, 2017 from bilateral bacterial otitis. His parents were found guilty of complicity in aggravated culpable manslaughter. They were given a suspended sentence of three months in jail. The parents had entrusted their son’s care to Pesaro homeopathic doctor Massimiliano Mecozzi, who is set to go on trial on September 24. The homeopath advised treatment with homeopathic products instead of the antibiotics which would have saved him, the court found. Francesco died after the otitis degenerated into encephalitis.

Such cases exemplify how misinformation overload, motivated ignorance, motivated reasoning, confirmation bias and science denial can generate the wishful thinking that misleads many of us into believing things that are not true. I therefore feel that it is wise and timely to caution: do not believe what you think!

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