From an early age I learned, from the advice of adults or from my own experiences—and sometimes the hard way—the relationship between cause and effect. It’s simple: if you touch the hot oven door, you’ll get burned! Subsequently, I discovered that there are a multitude of pressing uncertainties all around us in daily life. To figure out what actually causes the things that go on around us is added to the long list of life’s complicated issues.

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Where it cannot find a logical explanation for certain phenomena, the human mind seeks to identify potential causes, but in many cases they amount to nothing more than mere coincidence. In 1874, Ignaz Semmelweis, a Hungarian obstetrician at a hospital in Vienna, noticed the significant difference in maternal mortality rates between two of his wards, and began to closely observe the habits of his medical personnel. He noticed that the ward in which doctors and medical students attended births right after completing autopsies, and without following proper hygiene rules, had a much higher mortality rate. At his recommendation, the disinfection of hands before contact with patients was introduced, and the mortality rate dropped dramatically.

It is true that closely observing the circumstances which precede an event plays an important role in discovering the reasons which led to its occurrence. Unfortunately, we are often faced with the danger of thinking that merely observing an apparent connection between two consecutive realities is enough to establish a cause-effect relationship. “Does lightning produce the noise which follows it?” “Is dawn summoned by the rooster’s song?”

What causes the false cause

When we think that event 1 is the cause of event 2 simply because 1 happened before 2, we have fallen into the pitfall of a false cause fallacy. The main source of this fallacy is oversimplification, neglecting other factors which might have a determining role,  and prioritising the connection we first identified between the two events. We need sufficient and thorough arguments to prove that the first event is the cause of the second.

“Vaccines cause autism”. It’s unlikely you haven’t yet heard this statement. Autism, a complex developmental disorder affecting one’s ability to communicate and interact with others, is also unsettling due to the question mark which still hovers over its etiology. The confusion started with a 1998 article published by Andrew Wakefield and his colleagues in a prestigious medical magazine, which suggested a causal relationship between the MMR vaccine and autism. This article signaled the disease’s onset in the immediate period following the vaccination. As a result of neglecting certain research rules (low number of subjects, financial interests of the authors, etc.), the study was withdrawn, and its conclusions have been denied by multiple other researchers, who have stressed the genetic nature of this disorder.1

Nevertheless, some parents are still reluctant to vaccinate their children because of its supposed relationship with autism. The false cause fallacy plays a role one can hardly ignore, especially because the period in which the first signs of autism appear coincides approximately with that period in the child’s life when the vaccine is administered.

Many superstitions originate in this fallacy, completely ignoring the possibility that there might not actually be any connection between the two events, and that their succession is a mere coincidence.

Each of us has received, at least once in our lives, a chain message which threatened immediate negative consequences unless the message was forwarded. These messages continue to circulate because there are enough people who honestly believe that there is a slight chance that the message is true, and they try to avoid its threats. In the case of such people, any unfortunate event which happens after they ignore such a message will automatically be associated with the message, irrespective of the real cause.

There are professional athletes that have well-established rituals for match day, or who carry certain objects that they consider to be magical. What is the reason? They had positive results in the past after acting a certain way, and now they rigorously repeat those actions, hoping to obtain the same result once again. The explanation lies in the fact that we prefer to believe we have the power to control our lives and to influence the way in which the unknown is present in our lives.

On the other hand, we like to be right, to discover a general, valid “truth”, even if all we have at our disposal is our own experience and the experiences of those close to us. We therefore have the tendency to generalise what is happening to us, and to select only the data that confirms our theory, ignoring what does not “fit”.

Bearing this tendency in mind, if we drink a certain kind of tea when we have a headache, and we get the impression that it helps to alleviate the pain, before declaring with utmost certainty that we have identified a remedy against headaches, we must consider the existence of several possibilities: 1) the tea really does, in fact, have beneficial effects that are experienced by most consumers (this requires adequate checking, carried out by specialists, using a large sample of test subjects); 2) the tea only had a beneficial effect once (a real effect, or a placebo effect); 3) the mere ingestion of some liquid had a beneficial effect; or 4) the alleviation of the headache after consuming the tea was a mere coincidence. What we need to understand is that every time we declare with certainty that something caused something else without having enough logical evidence, we commit the false cause fallacy.

How to avoid the pitfall of the false cause fallacy

To avoid the false cause fallacy, it is useful to train our minds to adequately identify the circumstantial factors which favoured a certain result in the succession of two ordinary events. It is necessary to find the honest answer to the following questions:

1) Is there a real connection between the two events? More often than not we are presented with events that seem connected, synchronized even. Often, the temporal association is the only aspect in favour of there being a relationship between them (“Exactly at the moment I turned the TV off, my neighbour above me started to feel better”). Even if some actions may have unpredictable effects (the butterfly moving its wings in a certain area of the world causing a hurricane thousands of kilometers away), their causality with events needs to be tested.

2) If the connection is real, is it possible that other factors are involved which may influence the relation between the two elements?2

Researchers often begin by merely observing reality, but continue by experimenting and studying the impact of various variables on a certain phenomenon to exclude the possibility that the event was caused by a factor other than the one they suspect. It is important not only to know that there is a connection between the two events, but also to know how these are connected. (A person on the street waves and smiles at me: he/she probably knows me. Subsequently, my husband confirms that the person knows him and smiled at me because I was with him).

Therefore, a mere suspicion or a hypothesis is useful but not enough. It is imperative that this is confirmed. It is no doubt more laborious to do things this way, but I will thus move closer to the truth.

3) Is it possible to deal with reverse causality? There are multiple documented cases of animals manifesting very peculiar behaviours before earthquakes. Do animals cause earthquakes? The answer is, obviously, no. But they do respond to the beginnings of earthquakes in ways which precede the manifestations we humans perceive.

4) Could it be that the two events have a common cause? In some situations there is a real connection between two phenomena, proved even by statistical data. However, the relationship between them is not one of cause and effect, but that they both share the same cause. For instance, the increase in ice-cream consumption in summer, followed by a large number of suspected cases of sunstroke, is no evidence for the negative effects of this dessert, because both the consumption of ice-cream and the sunstroke are influenced by exposure to high temperatures.

5) When we look for the real cause of an event, it is essential to select the right informational sources, and to check whether these provide enough evidence. Evidence must be scientifically well-researched, and not just mere theories, to draw a certain conclusion. However, it is necessary to always remain flexible. It is possible that one of the factors involved in determining the cause of a state of affairs is not known or sufficiently studied at the moment of our analysis.

The strongest weapon against fallacies remains an open, lucid mind, which either has pertinent and up-to-date information at its disposal, or makes an effort to look for such information.

Frank DeStefano, Tom T. Shimabukuro, «The MMR Vaccine and Autism», in Annual Review of Virology, vol. 6, 2019, p. 585-600.
U. Hahn, R. Bluhm, F. Zenker, «Causal Argument», in Oxford Handbook of Causal Reasoning M. Waldmann, editor, Oxford University Press, Oxford, 2017.