The Semmelweis Reflex: An Ancestral Prejudice

Do you know someone who refuses to believe something if it goes against their beliefs or the socially established view? This is a really common cognitive bias. It defines the most inflexible minds and has had serious consequences throughout history.
The Semmelweis Reflex: An Ancestral Prejudice
Valeria Sabater

Written and verified by the psychologist Valeria Sabater.

Last update: 19 May, 2023

For centuries, science has had to fight against ignorance. For example, Giordano Bruno was a Dominican friar who lived in the 16th Century. He was a brilliant astronomer who dared to defend the Copernican model. Consequently, he affirmed that the sun was a star around which other planets revolved, such as the Earth.

In addition, he stated that there must be millions of other worlds in the universe and that, in all that vastness, there must be more forms of life. However, these ideas were considered heresy. In fact, the Roman astronomer ended up being burned at the stake. Michael Servetus suffered the same fate after defending his theory regarding pulmonary circulation.

Our history contains countless great discoveries that were originally ignored or even punished by death. This tendency to reject new perspectives because they contradict already established beliefs, defines the Semmelweis reflex. It’s a psychological reality that neither time nor modernity has been able to deactivate from our minds.

The Semmelweis reflex is a reasoning fallacy of which we’re often unaware.

Fragmented mind symbolizing the reflection of Semmelweis
Almost no one likes to read or have new approaches explained to them that go against their own beliefs.

Beware of the Semmelweis reflex

The Semmelweis reflex has its origins in another tragic figure in the history of science. Ignaz Semmelweis was a Hungarian doctor who made an important discovery in 1847. He found that handwashing with chlorine solution significantly reduced death rates from puerperal fever. Indeed, this simple practice prevented both pregnant women and newborns from dying.

Today, we know Dr. Semmelweis as the savior of mothers. However, in his day, he was ostracized. Moreover, he was branded as a charlatan and ridiculed. Indeed, his colleagues took it extremely badly that they were seen as responsible for the deaths of so many women and their children. How could they accept that something like not washing their hands was the cause of such high mortality rates in hospitals?

Sadly, he was fired which led to depression and alcoholism. The contempt of the medical community led him to end up in a psychiatric hospital, dying two weeks after admission at the age of 47. His life story now outlines the Semmelweis reflex.

A fallacy of reasoning that impedes progress

The Semmelweis reflex defines the almost instinctive rejection that we feel when exposed to information that contradicts our beliefs. As such, reading or having new paradigms explained to us that put in check the scientific schemas we consider to be valid causes us displeasure.

An investigation conducted by Vipin K. Gupta et al claims that the Semmelweiss reflex is an ancestral prejudice, a fallacy of reasoning long rooted in the human mind. It means we all prefer to adhere to existing beliefs and theories and don’t like new currents or ideas to contradict what we’ve always taken for granted.

As a matter of fact, if we look back to the past, we’ll see that all scientific progress has had to fight against skepticism. It happened to Albert Einstein with his theory of relativity and even to Steve Jobs when he created Apple. Their ideas and advances were the objects of criticism and numerous doubts. But, today, no one questions their revolutionary ideas.

A psychological phenomenon typical of inflexible minds

You might think that the Semmelweis reflex has its reason for being and its purpose. After all, we can’t accept every new trend that contradicts existing theories as valid. For example, what would happen if someone discovered the mechanism for time travel? Or, what if a drug was formulated that slowed down aging?

Being skeptical is a normal and desirable reaction when faced with new and contradictory information. We must all develop flexible, open, and critical thinking. Through this, we can analyze, compare, and create our own opinions about the data we receive.

The problem with the Semmelweis reflex is that, instead of allowing us to analyze new paradigms, we reject them out of hand. It’s a psychological phenomenon that ignores, blocks, and punishes any new current that threatens our existing beliefs.

Ignaz Semmelweis couldn’t convince doctors to sanitize their hands after autopsies and before attending to women in labor. It was Pasteur who finally instilled in the scientific community the need to carry out basic hygiene and disinfection tasks to prevent diseases.

Man with an enlightened mind applying the Semmelweis reflex
The Semmelweis reflex is deactivated by a curious, open, and flexible mind

How can we protect ourselves from this reflex?

Researchers often lament the fact that many scientific studies are rejected and not published because their proposals go against certain ideologies, beliefs, and even interests. In fact, the Semmelweis reflex may be preventing many innovative ideas from improving our quality of life and promoting progress.

This inherent human tendency is now curdled with economic and even political interests. We need to try and avoid reinforcing this bias and fallacy of reasoning. And we can do it by being aware of it. We simply need to adopt more open, curious, flexible, and also critical mental approaches.

Finally, we should try to avoid putting up walls in front of new currents of knowledge. We should first analyze what comes to us without rejecting it just because it’s contradictory. If we can tolerate these initial feelings and exercise our curiosity, we’ll be able to enrich ourselves on both personal and intellectual levels. This would obviously be extremely valuable.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Gupta VK, Saini C, Oberoi M, Kalra G, Nasir MI. Semmelweis Reflex: An Age-Old Prejudice. World Neurosurg. 2020 Apr;136:e119-e125. doi: 10.1016/j.wneu.2019.12.012. Epub 2019 Dec 16. PMID: 31837492.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.