Reductionism isn’t enough for public health

Chinese medical poster, 1933 (ref US NLM; image source here)

By Håkon Boman Andresen

The overarching goal of the public health sciences is to increase the population’s health. Society spends a lot of money each year on health research, which again is used to develop public policies and guidelines. However, is this causing the population to have better health?

I argue here that the Cartesian, dualist paradigm has skewed the way we understand the concept of health, in a negative direction. It presents a reductionist perspective that has led to health and the human body being understood as something physical, like a machine. The engine is built of small and large parts, and they work together to make the machine perform descartesbodymachineas it should. This has at least two consequences, which I believe can be quite severe for the experience of being a human. First, the reductionist perspective leads to the idea that if a person’s health is malfunctioning in some way or another, you can fix the parts that are malfunctioning, and then health will be restored. This might be fine if we are dealing with a broken arm.

With other illnesses, for example mental illnesses such as schizophrenia, depression or anxiety, how could this work? It is not possible to replace a malfunctioning brain or any of its parts. The reductionist might say “not yet”, or that there are drugs which can treat these issues. However, it is not the malfunctioning of a single part in the brain that causes depression, but a malfunctioning of an entire situation, such as an unstable life situation combined with individual factors.

Another consequence of the reductionist perspective is that health is researched in a closed system. Interventions where the participants are carefully selected, and those who do not fit the criteria is not included in the study, are used to find causal mechanisms (often drawn on correlations). Then generalizations are done to entire populations. As well, probabilities derived from epidemiological studies are used to predict outcome. One consequence of this is that a lifestyle with regular exercise and healthy food (whatever this means) is deemed the best lifestyle, because the probability for early mortality is lower with this group, and also includes many other effects which most people find positive (such as wellbeing, better functioning in one’s daily life, etc.). However, regularly exercising and only eating healthy foods is not a given for being healthy: there is plenty of evidence that this can be a hazardous lifestyle. Eating disorders, bodily wear and tear, etc., are just some of the possible consequences/effects of such a “healthy” lifestyle. Still, there are plenty of RCTs and large-scale population studies, which use statistical trends within the population to draw causal conclusions on an individual level. This has the potential to be harmful to certain individuals. On the other hand, alcohol, smoking, junk food and drugs is understood as unhealthy, because these are correlated with early mortality and diseases.

This is not to say that regular exercise and the foods normally associated with being healthy cannot contribute towards health, but health consists of so much more. Alcohol, cigarettes, drugs and junk food can also contribute towards better health! Enjoying a burger with fries and an ice cold beer (or five) with good friends can increase happiness and relaxation and reduce stress, which most people would agree is important for living a healthy life. Reductionist methods have their place within health research, but only up to a certain point. There are situations in real life that we cannot reduce to a minimum, and there are times we can know the smallest parts, but still not be able to predict the outcomes. And even though some things might be healthy or unhealthy for the human body in some way, they can also have the opposite effect in another way.


Hence, I am convinced the reductionist point of view is less than effective when it comes to health as a holistic concept, which is concerned with the well-being and functioning of the entire human organism; mind, body and everything else (it’s quite difficult to escape Descartes’ dualistic paradigm). Still, I am unsure if it is correct to call much of the research within public health reductionist; descriptive might be a better term. In Norway, there are large population-based studies on the population’s health. These studies find that those who partake in regular exercise and eat certain foods have lower probability for early mortality and disease, while those who drink and smoke have a higher risk. There is then made a causal claim that regular exercise and healthy eating reduces mortality and disease, and drinking and smoking increases mortality and disease, and recommendations to the population are then made. However, this knowledge, combined with a reductionist way of thinking, has created normative ideals about how we should live our lives. It seems today that exercise and eating “healthy” foods is understood as not only something that is necessary to be healthy; it is also a virtue and a duty to exercise and eat correctly. And if you smoke at all, drink more than recommended, you have a body which looks like it’s had too much junk food or you do illicit drugs, people judge you as unhealthy and morally faulted.

This is where Popper’s propensity theory enters the picture. This theory disagrees with the probability point of view, because it is an oversimplification. When it is found that those who partake in regular exercise have lower rates of early mortality, it does not mean that regular exercise is either sufficient or necessary for experiencing good health. There are many instances of physically active people suffering early deaths. And when smoking is found to increase mortality within a population, it doesn’t mean that everybody who smokes will die an early death; there are plenty of smokers who live until they’re 90 (Churchill comes to mind). This way of thinking of probability is what Popper would call a subjective theory of probability, where only one or a few variables are considered relevant.

However, life is complex, every situation is unique, and it is meaningless to talk about probabilities for a single person, based on probabilities within the entire population. Hence, Popper argues for a propensity perspective, where we rather think about inherent propensities within situations. Therefore, for many people, regular exercise is a propensity that disposes towards good health, but for some, regular exercise might dispose towards worse health or not do anything at all. Illicit drugs might be correlated with negative health outcomes, but this doesn’t mean they necessitate early mortality or ill health.

HumanMachineHuman beings are not machines, and the whole cannot necessarily be fixed by fixing the single parts. If the world was like this, it would be great, because the world would have been much simpler and easier to understand. However, look at it the other way around, and you see that the human body will not necessarily be destroyed or seriously damaged if something isn’t optimal or adhering to statistical trends. Instead of generalizing and telling people how to live according to what is healthy for a majority, I would like to see acceptance for a plethora of possible lifestyles, for there are many roads that all can lead to healthy lives, given the right circumstances. Life and health is far from black and white and full of uncertainties, so pick your battles and enjoy something “unhealthy” every now and then. Nobody gets out alive, anyway.

To quote a song by the Norwegian band Highasakite:

Science and blood tests

Doesn’t say anything ‘bout how I feel

Author: CauseHealth

CauseHealth - Causation, Complexity and Evidence in Health Sciences

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