Homunculus Fallacy

31 Homunculus

KARL PILKINGTON: Does the brain control you or are you controlling the brain? I don’t know if I’m in charge of mine. Do you know what I mean though by that? […] I was making a shopping list, alright. Going, right, I need some rice, kidney beans, and I thought I had everything and I sort of was rolling up the paper and then something went “oh an onion.” My brain sort of went, “you forgot something.” I didn’t think I forgot.…

RICKY GERVAIS: No, no, you are your brain.

KARL: I was in control of my brain when I was writing down rice and kidney beans […] so what I am saying is who’s in charge? […] It just made me think, that was weird, who reminded me of that?

RICKY: You did! No, you are your brain! […]

KARL: How does your brain work? You give it information, don’t you? […] If I sat in a room with nothing, not feeding it anything, it wouldn’t know anything.

RICKY: No, no, there’s this thing that there are two yous. It’s this thing where there’s […]

STEPHEN MERCHANT: There’s Karl and Karl’s brain!

RICKY: There’s not a duality in this! If you go “come on, come on now – think!” that’s the brain saying that to itself. […] You are your brain. If you are anything, you are your mind, your brain, your collection of memories, your personality.

Selections from Ricky Gervais Podcast, Series 2, Episode 6

The homunculus fallacy (HmF) occurs when an argument attempts to explain a phenomenon in terms of the very phenomenon it was supposed to explain. This creates an infinite loop—or infinite regress—that explains nothing. For example:

JANE: How do you think life ultimately began? SARAH: I think aliens came here from a distant galaxy and planted seeds millions and millions of years ago. JANE: Okay, so how did those aliens and their galaxy begin? How did life start there? SARAH: Well, aliens from another farther galaxy came there and planted seeds billions of years ago.

The vicious circle is the hallmark of the fallacy. Even if the explanation accidentally turns out to be true (it might actually be aliens all the way down), the reasoning itself never resolves the original question, because each answer just pushes the real explanation one step further back.

Historically, the fallacy is tied to theories of vision, sometimes called the Cartesian theater. Someone might explain sight by saying that light forms an image on the retinas, and then a little person—a homunculus—inside the brain watches those images as if on a screen. But then how does that homunculus see? If you propose another homunculus inside its head, the explanation regresses endlessly and never gets closer to understanding vision.

The term was coined by Anthony Kenny in his 1971 essay “The Homunculus Fallacy.” Drawing on Wittgenstein, Kenny describes the error of ascribing to a part of a human being (like the brain) attributes that properly belong only to the whole person: “This dictum is often rejected in practice by psychologists, physiologists and computer experts, when they take predicates whose normal application is to complete human beings or complete animals and apply them to parts of animals, such as brains, or to electrical systems.” For instance, neuroscience shows the hippocampus plays a key role in memory, but it would be fallacious to say, “My hippocampus remembers everything.” It is you, the whole living person, who remembers—not a detached lump of tissue. A hippocampus removed from the body wouldn’t remember a thing. Similarly, other embodied expressions like “my stomach was craving chips” or “my legs were itching to dance” attribute agency to body parts, when in fact it is the whole person who craves or itches.

The fallacy also appears in abstract contexts such as epistemology. Consider someone defending their faith by appealing to “faith in faith”: “I have faith that my faith in God is justified.” If you then ask why they trust that faith, they might reply, “Because I have faith in the faith that supports my faith in God.” This produces the same endless regress; every layer of faith is justified by a further layer of the very thing it attempts to ground, ultimately explaining nothing. Some may try to break the loop by pointing to reason as the foundation for faith, but then the foundation of reason is again claimed to be God (faith), circling back to the starting point.

In the podcast exchange above, both Karl and Ricky commit the fallacy, albeit in different ways. Karl talks about his brain as a separate homunculus controlling him—a classic Cartesian theater. Ricky, on the other hand, insists that Karl is his brain, omitting the body entirely. Kenny’s formulation warns against both moves: Karl’s mistake is treating his brain as an internal homunculus, while Ricky’s is ascribing whole-person attributes to the brain alone. The remedy is straightforward: speak of oneself and others as whole human beings—mind and body together—not as a severed brain or a ghost in a machine. The temptation to offer explanations that spiral into infinite regress is common, but recognizing the pattern allows us to demand answers that actually advance understanding rather than endlessly postponing it.