This error in reasoning described by philosophers of the mind indicates a common fault in psychology.
When you think of something that brings you back to your past memories, is it you who reflects, or does your brain reflect? The fact of turning your attention towards mental phenomena as internalized as memories can indicate that everything you do at that moment is limited to internal activity, something that is carried out by the nervous system.
But, on the other hand, could we not say that it is always the brain that thinks and feels, since our whole mental life is linked to it? It is not necessary to stick to what happens when we remember: when talking to someone, the brain transforms concepts into words, right? In fact, we could even say that it is not the whole brain, but a part of it, that thinks and plans: what the prefrontal cortex does is not the same as what the medulla oblongata does.
If these questions have led you to think that really your real “I” is your brain enclosed in a set of muscles and bones, just as a machinist operates a cabin train, many philosophers, psychologists and neuroscientists would tell you that you have fallen in what is known as the mereological fallacy. Let’s move on to the corresponding question.
What is the mereological fallacy?
Although the study of mental processes and the brain is something very complicated, that does not mean that it is impossible. Currently we have a level of technology that allows us to keep systematic records on nervous activity and behavior, with which lines of research that a few decades ago seemed like science fiction stories are now a reality.
Now, many philosophers would say that the revolution in technological advances that we have experienced in the second half of the twentieth century and in the twenty-first century has not been accompanied by a revolution of ideas comparable to the previous one; at least, as regards our way of thinking about how the human brain and behavior work. Many times we fall into something that some philosophers have called a mereological fallacy.
This concept was promoted by the philosopher Peter Hacker and the neuroscientist Maxwell Bennett who, in their Philosophical Foundations of Neuroscience , pointed out an error that, according to them, most researchers in the brain and in the field of psychology had been making: to confuse the part for the whole. For example, affirming that the brain reflects, chooses, values, etc.
From the point of view of these two authors, the way in which mental processes are conceived by both the majority of people at the popular level and many researchers in the scientific field is not very different from those who believe in a soul that, from somewhere of the brain, governs the body. Thus, the mereological fallacy is not technically a fallacy because it does not arise from an erroneous argument (although it is in the broadest sense of the term), but rather a failure to attribute a subject to a predicate.
Thus, falling into the mereological fallacy is to attribute to the brain, or some of its parts, properties and actions that are actually carried out by people. In the same way that it would be absurd to say that it is not the hawk but its wings that fly, it would be fallacious to say that the brain thinks, reflects or decides. We often get carried away by these assumptions simply because it is easier for us to understand how the mind works if we allow ourselves to be carried away by reductionism, and not because scientific research has shown that this set of organs reason or think apart from the rest of the body.
In other words, the mereological fallacy consists in understanding the human mind in a very similar way to what philosophers like René Descartes did to explain what the psyche is by appealing to the spiritual and the divine. This is a deeply rooted mistake.
From Cartesian dualism to metaphysical monism
The study of the brain has been marked for centuries by dualism, that is, the belief that reality is composed of two radically different substances, matter and spirit. It is an intuitive belief, since it is easy to consider that there is a clear division between the own state of consciousness and almost everything else, the “external”, it is very simple.
In the seventeenth century, René Descartes created a philosophical system that formalized the relationship between the body and the mind; just as he understood this relationship. Thus, the mind, the spiritual, would be seated in the pineal gland of the brain, and from there it would govern the acts performed by the body. The precedent of the mereological fallacy, thus, was present from the beginning of the formalization of the scientific study of the brain, and of course this affected psychology and philosophy.
However, the openly declared dualism did not last forever: already in the twentieth century monistic approaches, according to which everything is matter in motion, gained hegemonic status. The philosophers and researchers who point to the existence of the mereological fallacy as a recurring problem suggest that this generation of researchers continued to treat the brain as if it were a synonym for the soul or, rather, as if it were a miniature person who controls the rest of the organism . That is why the mereological fallacy is also called the homunculus fallacy: it reduces human properties to small and mysterious entities that supposedly inhabit some corner of our heads.
Thus, although dualism was apparently rejected, in practice it was still considered that the brain or its parts could be understood as an essence to which our identity was attributed. The monists used ideas based on metaphysics to change the name of the soul and baptize it as “brain”, “frontal lobe”, and so on.
The consequences of the mereological fallacy
The mereological fallacy can be understood as a poor use of language when talking about how mental processes really are and what the human condition is. It is not by chance that Peter Hacker is a follower of the work of Ludwig Wittgenstein, a philosopher known for having argued that the failures of philosophy are actually inappropriate uses of language. However, falling for this fallacy means much more than not speaking properly.
A linguistic error that can have consequences beyond the simple confusion of terms is, for example, looking for parts of the brain responsible for thinking or decision-making, something that usually leads to analyzing smaller and smaller areas of the brain. Let us remember that this, considering the existence of the mereological fallacy, would be like attributing to the axis of the wind mills the property of moving the blades.
In addition, this trend is a way to continue believing in something very similar to the soul without calling it by that name. As a consequence, the belief that there is an essence from which our actions and decisions are born remains intact, and the body / mind dualism, or rejection of the idea that we are not fundamentally different from any other animal, is still there, in disguise.
A frequent, automatic and unconscious mistake
The concept of mereological fallacy has not been unanimously accepted by neuroscientists or philosophers of the mind. John Searle and Daniel Dennett, for example, have been critical of it. The second, for example, affirms that it is possible to talk about “partial” actions and intentions and attribute them to the brain and its sub-systems, and that delaying the meaning of the terms “thinking” or “feeling” in this way is not harmful. It is a point of view that bets on pragmatism, downplaying the negative consequences of the mereological fallacy.
In addition, it may come to be thought that when talking about the brain outside of scientific fields, whether in day-to-day or popularization, it is very difficult to talk about the functioning of the brain without doing it as we would about of people. This has made it a relatively little known idea: it describes something that we have been doing for centuries and that we do not normally see as a problem that affects us. Essentialism is something that is very attractive when it comes to explaining all kinds of phenomena, and if we can reduce the causes of something to a clearly identifiable element isolated from the rest, we usually do so unless we are attentive.
For the moment, then, it is difficult to find a way to talk about the mechanisms of the nervous system without automatically and without realizing the mereological fallacy. Doing so requires entering preambles that few outreach initiatives can resist, and having experience and training in philosophy and neurosciences that few people can afford. However, that does not mean that it is better to forget the fact that this problem is still there, that it is important to take it into account both in research and in faculties related to Psychology and Philosophy, and that metaphors about how the brain works they must be taken as such.