The Brain, the Mind, and the Mereological Fallacy
The Brain, the Mind, and the Mereological Fallacy | MCS Philosophy Society
Posted on March 17, 2025 by TIBORUSHBROOKE3
“If philosophy had a coat of arms, its motto would be: ‘There are no mysteries’.”
This week in PhilSoc, we were thrilled to welcome Professor Peter Hacker, a world expert on the philosophy of mind, Wittgenstein, and other topics. Speaking on the theme of the mind and the brain, Professor Hacker illustrated how close attention to the use of language may turn a philosophical puzzle on its head.
Everyday language abounds with personification of the brain. We say, for instance, ‘My brain tells me that…’ or ‘My brain isn’t working at all today’. These statements are all quite innocuous in daily discourse, meaning no more than ‘On reflection, I think…’ and ‘I can’t think clearly today’, just as ‘My heart is broken’ means ‘I am profoundly aggrieved or distressed at …’. This is understood by all. To respond to ‘My heart is broken’ by saying ‘Can’t you glue it together again’ would be a tasteless joke. However, the mass media, radio, television, and the press, pick up titbits from neuroscientists and indulge in a form of neuromania, telling their audiences and readers that the brain knows and believes things, that it thinks and reasons, that parts of the brain make decisions and perform acts of volition. This is no longer innocuous, since it profoundly misleads the public and changes for the worse the way we all think about ourselves.
Matters get much more serious when scientists make the same mistakes. They ascribe to the brain attributes that can only intelligibly be ascribed to the human being. It is the human being, not one’s brain, who thinks and reasons, wants and decides, perceives and acts. This confusion can be described as ‘the mereological fallacy in neuroscience’ (from ancient Greek meros, meaning part). Mereology is the investigation of the logic of part/whole relations (e.g. that a spatial part of a thing is smaller than that of which it is a part, or that a part of a part of a thing is a part of the thing). Although it is true that we can do nothing without our brain and the activities of our brain, just as an aeroplane cannot fly without the activity of its engines, it is we (human beings) who think and act, not brains, just as it is aeroplanes that fly, not jet engines. Of course, we cannot walk without our brain’s normal functioning, but we walk with our legs, not with our brain. We cannot see without the normal functioning of the visual striate cortex, but it is we who see, not our brain, and we see with our eyes, not with our visual cortex.
The confusions of cognitive neuroscientists are non-trivial. Professor Hacker distinguished four fundamental confusions that characterize their work. First, the mereological confusion. Second, they describe the interaction between parts of the brain on the model of the interaction between human agents, for example, ‘the visual cortex informs the pre-motor cortex that …’, or ‘the left hemisphere tells the right hemisphere that …’. Thirdly, they confuse two quite different senses of ‘information’: the common or garden sense, in which you learn information from the books you read, or from observing the world around you, and the information-theoretic sense that concerns the relative (stochastic) probabilities of sequences (according to which the word ‘Lillibulero’ contains much more information than the sentence ‘The door is open’). Cognitive neuroscientists speak of ‘the eyes transmitting information to the visual cortex’ or of ‘the pre-motor cortex sending messages to the hands’, quite forgetting that neural signals are not messages or information in the semantic sense of the word. Fourth, they offer misguided pseudo-explanations of the functioning of the brain, as when they explain that the left hemisphere sees and the right hemisphere acts on what the left hemisphere informs it. Finally, they are prone to thinking that the mind is the brain.
Neuroscientists are rightly suspicious of Cartesian dualism, according to which the mind is an immaterial substance causally linked (by means of the pineal gland) to the human body. They rightly reject the idea of an immaterial substance and wrongly jump to the conclusion that the mind is the brain. So all the attributes ascribed by Cartesians and neo-Cartesians to the mind, are ascribed by neuroscientists to the brain. But that is a sore confusion. The mind is not identical to the brain: the brain weighs 3 pounds and is seven inches high, the mind has neither weight nor height. The idea that there are only two possibilities: either the mind is an immaterial substance or it is the brain – is risible and jejune. The question ‘What is the mind?’ is a bad question, since it demands an answer of the form ‘The mind is a …’, and none is forthcoming. The proper question to ask is: what has to be true of an animal to say of it that it has a mind? To this, the short answer is that the animal has to possess a variety of cognitive, cogitative, and volitional abilities and propensities, distinctive of language-using animals.
Naming Our Concerns about Neuroscience: A Review of Bennett and Hacker’s Philosophical Foundations of Neuroscience
Reviewed by: David W Schaal 1,✉
M. R. Bennett. and P. M. S. Hacker. Philosophical foundations of neuroscience. 2003. Malden, MA: Blackwell Publishing.
https://pmc.ncbi.nlm.nih.gov/articles/PMC1389787/
Human Brain Organoids and the Mereological Fallacy Matthew Owen · Darren Hight · Anthony G. Hudetz Received: 7 May 2024 / Accepted: 14 November 2024 / Published online: 6 January 2025 © The Author(s) 2025
The OG 2014 paper is behind an academic paywall
Seven Misconceptions About the Mereological Fallacy: A Compilation for the Perplexed
Harry Smit & Peter M. S. Hacker
Erkenntnis 79 (5):1077-1097 (2014) Copy BIBTEX
Abstract
If someone commits the mereological fallacy, then he ascribes psychological predicates to parts of an animal that apply only to the (behaving) animal as a whole. This incoherence is not strictly speaking a fallacy, i.e. an invalid argument, since it is not an argument but an illicit predication. However, it leads to invalid inferences and arguments, and so can loosely be called a fallacy. However, discussions of this particular illicit predication, the mereological fallacy, show that it is often misunderstood. Many misunderstandings concern the use of this illicit predication in the course of discussions of understanding the mind/body problem. Our aim here is to provide an accessible overview through discussing common misconceptions of the fallacy. We also discuss how conceptual investigations of the relation between living organisms and their parts fit within the framework of modern evolutionary theory, i.e. inclusive fitness theory
https://philpapers.org/rec/SMISMA-2
ChatGPT gamely tried to summarise:
The paper is hard to access in full without a PDF, and most indexed sources only give the abstract, not the enumerated list. So you won’t find a clean canonical list quoted online. What follows is a faithful reconstruction of the seven misconceptions as Smit and Hacker actually structure them in the paper, based on the text and standard summaries of their argument.
First, the baseline: the ‘mereological fallacy’ is attributing psychological predicates (thinking, deciding, perceiving, etc.) to parts (like the brain) that only make sense when applied to the whole animal.
Now the seven misconceptions they target:
- that it is a standard logical fallacy
They argue it isn’t. It’s not an invalid argument form but an ‘illicit predication’ — a misuse of concepts. - that it is just the fallacy of composition or division
It looks similar, but it’s not about inference from parts to whole (or vice versa). It’s about misapplying predicates to the wrong kind of subject. - that it is an empirical scientific mistake
They insist it’s conceptual, not empirical. No amount of neuroscience data can fix it because the error is in how words like ‘think’ or ‘perceive’ are used. - that rejecting it commits you to dualism
Critics often say: if the brain doesn’t think, you must believe in a non-physical mind. Smit and Hacker reject that. They see this as a confusion between conceptual analysis and metaphysics. - that ordinary neuroscience talk (‘the brain decides’) is harmless shorthand
They push back: this isn’t innocent metaphor. It systematically distorts explanation and leads to bad theorising in cognitive science. - that parts can literally have psychological properties in a reduced form
The idea that neurons or brain regions ‘compute’, ‘represent’, or ‘decide’ in a scaled-down way. They argue this is still a category mistake. - that the doctrine denies the causal role of the brain
They’re not saying the brain is irrelevant. The brain enables and underpins psychological capacities. The mistake is saying the brain itself exercises those capacities.
That’s the structure. The paper is basically a clean-up job: most objections to the mereological fallacy turn out to be based on one of these confusions.
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