Disbelief in science and the difference between correlation and causality

Before the scientific method existed, people tried to understand the world by other means: Tradition, intuition, spirituality, authority or anecdotes. For thousands of years, something was considered “true” if it was proclaimed by religious leaders, monarchs or charismatic personalities. Power and self-assurance replaced evidence. The motto: correlation instead of causality.

The 4 humors

An example from the history of medicine shows this dramatically: the theory of humors dominated thinking for almost two millennia. Diseases were attributed to an imbalance of the four humors – blood, phlegm, black bile and yellow bile. This idea originated in the writings of ancient physicians and was systematically written down by Galenos of Pergamon around 200 AD. Observation or experimental verification? Not a chance.

The consequences up to the 19th century

Bloodletting became the standard therapy – for fever, inflammation or respiratory diseases. Even George Washington, the first president of the USA, died in 1731 after his doctors drained almost 50% of his blood volume and gave him laxatives to treat a sore throat that is easily cured today. At the time, this was not “alternative medicine”, but accepted practice in the context of humoral medicine. And the results were correspondingly devastating.

For most of human history, the average life expectancy was just over 40 years. Children died of diarrhea, infections or malnutrition. Around 1800, about 30% of children did not survive their first 12 years. Women regularly died in childbirth, minor injuries such as simple abrasions could be fatal, as it was easy to become infected with the bacterium Clostridium tetani and then die of tetanus. However, people did not know this and believed that “bad air” or curses or demons were the cause of the illness. Therapies consisted of bloodletting, mercury applications, leeches or other questionable “natural” remedies. There was no systematic procedure for testing ideas or weeding out false ones. Anyone who questioned the prevailing beliefs risked being branded a heretic.

That was the world before the scientific method. Today we know better – and yet the temptation to rely on gut feeling, groupthink in Facebook groups or the persuasive power of influencers is still great.

Correlation is not causality

A central problem of scientific disbelief lies in the misunderstanding between correlation and causality. Two things can occur at the same time without one causing the other. For example, if you observe that people are eating more ice cream and at the same time read that there are more deaths by drowning, you might conclude that eating ice cream somehow leads to drowning. In fact, there is a third variable – the weather – that explains both phenomena. On hot days, more people go swimming and therefore more drown. And, of course, many people treat themselves to an ice cream.

This is exactly where the scientific method comes in: Many hypotheses on a question are put forward, tested, rejected (falsified) and the hypothesis remaining at the end is repeated and independently tested. This is the only way to clarify whether a correlation is causal or merely coincidental. Without this distinction, we remain susceptible to false conclusions – and to the persuasive power of influencers and Facebook gurus who sell correlations as pseudo-scientific “evidence”.

Why this is relevant today

In times of fake news, health myths and conspiracy narratives, it is clear how quickly old patterns return. Okay, the ice cream example is deliberately a bit silly because it can easily be identified as fake news. However, a convincingly presented “That helped me” still replaces hard data for many people today. “I got the Covid vaccination and then developed histamine intolerance, so the vaccination is the trigger for my histamine intolerance” is a common refrain. But personal anecdotes are not proof. Not even if several people in a Facebook group keep claiming it. Correlation is not causation.

Science is laborious, critical and often uncomfortable. But it is our best tool for exposing false causalities and understanding real connections. It was and is our way out of humorism, belief in esotericism and astrology, trust in demon conjuring and prayer as a cure for illness or belief in bad air as a trigger for malaria.

History reminds us that without critical examination, we remain susceptible to errors that not only influence our thinking, but can also cost us our lives. But critical examination must be learned and follow scientific methods. It doesn’t just mean shouting out loud that the evil scientists are trying to lead us all astray. It means either becoming a scientist yourself or believing experts.

Without modern scientific methods, we would still be knocking on heaven’s door today at an average age of 40 because we have scratched ourselves while weeding and contracted tetanus or measles while going out. Thanks to these methods, however, we are no longer afraid of most infectious diseases and have an average life expectancy of over 80 years.

Further reading

1. https://www.wgff.de/aachen/download/d_kindersterblichkeit.pdf
2. Papyrus Ebers und die antike Heilkunde, Akten der Tagung vom 15.-16. 3. 2002 in der Albertina/UB der Universität Leipzig, Edited by Hans-Werner Fischer-Elfert, 2005, Harrassowitz Verlag Wiesbaden, ISSN 1613-5628, ISBN 3-447-05209-0
3. https://home.uni-leipzig.de/schreibportal/korrelation-als-kausalitaet/
4. Sudarshan, Raghav et al, Tetanus: recognition and management,The Lancet Infectious Diseases, Volume 0, Issue 0