Stomachs don’t eat lunch. Eating lunch is something that a whole, embodied person does. We understand the role that stomachs play in the lunch-eating process; we appreciate that people can’t eat lunch without them. Brains don’t think. They don’t learn, imagine, solve problems, calculate, dream, remember, hallucinate or perceive. To think that they do is to commit the same fallacy as someone who thought that people can eat lunch because they have little people inside them (stomachs) that eat lunch. This is the mereological fallacy: the fallacy of confusing the part with the whole (or of confusing the function of the part with the telos, or aim, of the whole, as Aristotle, who as usual beat us to the crux of the problem, would say). Nor is the homunculus a useful explanatory device in either case. When I am asked how we might explain the workings of the mind without recourse to mental representations (students often ask this), the reply is that we fail to explain anything at all about the workings of the mind with them. “Remembering my mother’s face is achieved by inspecting a representation of her face in my mind.” This is explanatorily vacuous. And if reference to representations does nothing to explain dreaming, imagining and remembering, it is particularly egregious when mental content is appealed to for an explanation of perception itself, the original “Cartesian” mistake from which all of the other problems derive.
A person is constantly developing and revising an idea of his or her world; you can call it a “picture” if you like (a “worldview”), but that is figurative language. A person does not have a picture inside his or her body. Brains don’t form ideas about the world. That’s the kind of thing people do.
This original Cartesian error continues to infest contemporary cognitive science. When the brain areas in the left hemisphere correlated with understanding speech light up and one says, “This is where speech comprehension is occurring,” the mereological fallacy is alive and well. Speech comprehension is not something that occurs inside the body. Persons comprehend speech, and they do it out in the “external” world (the only world there is).
Positing representations that exist inside the body is an instance of the mereological fallacy, and it is so necessarily, by virtue of the communicative element that is part of the definition of “representation,” “symbol” etc. Neither any part of the brain nor the brain or nervous system considered as a whole interprets anything. The key to developing a natural semantic of intentional predicates is to realize that they are predicated of persons, whole embodied beings functioning in relation to a larger environment. Brain/body dualism can be presented as non-dualist (isn’t the brain a physical organ of the body?), but it is an insidiously Cartesian view that gets us no farther in naturalizing intentional predicates.
Suppose that you are driving down the freeway searching for your exit, and you’re worried you might have passed it. You remember that there are some fast-food restaurants at the exit, and you think that one always feels that they have gone too far in these situations, so you press on, keeping an eye out for the restaurants. However you manage to do this, it is no explanation to say that you have done it because your brain remembered the fast-food restaurants, and has beliefs about the phenomenology of being lost on the freeway, and decided to keep going and so forth. That’s like saying that the way you had lunch was that your stomach had lunch.
This realization may also be momentous for brain science. Go to the medical school bookstore, find the neurophysiology textbooks and spend a few minutes perusing them. Within the first minutes you will find references to the “movement of information” (for example by the spinal column), “maps” (for example on the surface of the cortex), “information processing” (for example by the retina and in the visual cortex) and so on. (Actually my impression is that brain scientists are relatively sophisticated in their understanding of the figurative nature of this kind of language compared to workers in other areas of cognitive science; the point is just that representational talk does indeed saturate the professional literature through and through.) But if brain function does not involve representations then we don’t know what brains actually do, and furthermore the representational paradigm is an obstacle to finding out: think of all those experimentalists developing protocols to try to “locate the symbolic architecture.” They might be looking for something that isn’t there. If there is any possibility that this is true these arguments need to be thoroughly explored at the very least.
Taking the argument from the mereological fallacy seriously also draws our attention to the nature of persons. It follows from what has been said that the definition of “person” will be operational. Operational definitions have an inevitably circular character: a person is any being that takes intentional predicates. In fact there is not a “machine-language” explanation of personhood. Kant, writing in the late 1700s, is fastidious about referring to “all rational beings,” he never says “human beings”; he understands that when we are discussing the property of personhood we are discussing (what I would call) a supervenient functional property (Kant would call personhood “transcendental”), not a contingent physical property. However Kant is programmatically intent on limiting the scope of materialism as such and thus fails to develop non-reductive materialism. Instead he imports the mental (“reason”) from the noumenal world and ignores the problem of the relationship between transcendental reason and the human body (this is not to say that he does not acknowledge the role of our particular, contingent sense organs in shaping our representations of the world to the extent that those representations are themselves contingent and particular to us).
With Kant we remain in our bodies but not of them.
Once one recognizes that intentional predicates are predicated of whole persons – once one sees that positing mental representations necessarily commits the mereological fallacy – the question of representation is settled. It is I, and not some “brain state,” that is remembering my mother’s face. However there is a tight network of arguments and assumptions, centered on a model of intentional states as “propositional attitudes,” that will have to be disentangled to the satisfaction of readers who are disposed to defend representations. After that unpacking is done the reader will also reasonably expect some account of a non-representational analysis of intentional predicates, something that is not achieved by simply pointing out the mereological fallacy.