In a recent episode of the GeekPlanet podcast, hosts Robert J. Marks and Brian Krouse talked to Dr. Joseph Green*, a computational neuroscientist and contributor to the book Minding the Brain (2023).
Their discussion centered not on the technical details of neuroscience, but on the deeper philosophical questions it raises especially the claim that we are nothing but our brains. The result was an illuminating conversation about what neuroscience can explain, what it can’t, and how philosophy fits into the picture.
Neuroscience works with what it can measure — but that’s not everything
Dr. Green acknowledges that neuroscience, like all sciences, relies on tools. These tools measure what is physical and detectable: electrical spikes, chemical signals, neurotransmitters, and neural circuits. Because these tools focus on the material aspects of the brain, scientists naturally spend most of their time studying neurons and their activity.
But there is a catch. The ability to measure something does not automatically make it the whole story. Green argues that neuroscience has developed a “flattened” view of the brain — one that unconsciously equates the measurable with the meaningful. In other words, because we can record neurons, we tend to treat neurons as if they are the entire explanation of the mind. This can lead to a subtle but powerful bias: reducing the mind to whatever our instruments are capable of detecting.
This reduction is often expressed through materialistic monism, the belief that everything about human beings is ultimately just matter in motion. Green says this belief is not proven by neuroscience — it is simply assumed. Science can only study physical processes, so it is limited to material explanations. Thus, it cannot, by its own methods, rule out the possibility that aspects of the mind may be immaterial.
The border between neuroscience and philosophy
Krouse asks whether this limitation means that philosophical questions — such as the nature of the soul, free will, or consciousness — lie outside the reach of neuroscience.
Green acknowledges that it does. Neuroscience can describe correlations, like which parts of the brain light up during a decision. But it cannot say whether the decision itself originates entirely in the brain or whether there is an additional non-physical component involved.
This does not mean neuroscience is failing. Rather, it means that neuroscience simply does not have the tools to answer metaphysical questions. For example, if scientists someday learn to stimulate a mouse’s brain so it turns left instead of right, that does not prove anything about whether the mouse freely chose one direction or another. It only shows that physical interventions can influence behavior — not where the original intention comes from.
Green emphasizes that the field is still young. We are far from understanding the total causal structure of the brain, and therefore there remains “logical space” for different metaphysical models.
Neuroscience may eventually constrain some philosophical theories, but right now it cannot rule them out.
Why materialism should not be treated as scientific fact
Many popular books and articles claim that neuroscience has shown humans to be nothing more than “a bunch of neurons.” Green strongly pushes back against this idea.
He stresses that neuroscience has not demonstrated that all mental life reduces to brain activity, and more importantly, it does not even have the ability to test that hypothesis. Yet the cultural influence of neuroscience is so strong that people often treat neuroscientific claims as ultimate proof. Green describes this as a kind of “appeal to authority,” where adding a neuroscientific explanation makes a claim seem more credible — even when it adds nothing of substance.
This is why Green believes scientists must remain humble. Neuroscience can describe the workings of the brain, but it cannot answer deeper questions about personhood, purpose, or the existence of an immaterial mind. For those questions, philosophy remains essential.
The challenge of defining consciousness
Marks and Green also discuss the difficulty of defining consciousness, a term that everyone uses but few define clearly. Scientists such as Christof Koch try to offer operational or clinical definitions — useful for determining whether a patient is conscious during surgery or after injury. But these practical definitions do not address the philosophical mystery of subjective experience — what it feels like to be conscious.
Green argues that both perspectives are important, but they operate at different levels. Understanding when a patient is conscious is critical in medicine. But understanding what consciousness is requires philosophical reflection—not just brain scans.
Neuroscience, AI, and human uniqueness
In the final portion of the interview, Marks raises the question of whether growing human brain tissue or developing advanced AI could someday create a form of “super-intelligence.” Green is skeptical. Biological intelligence, he says, is fundamentally different from artificial systems because it is tied to the body, sensations, and emotions. Human intelligence is not just computation — it is lived experience.
A call for intellectual humility
Green ends with an appeal for humility. Neuroscience is powerful and rapidly advancing, but it cannot yet — and may never — explain the full reality of the human person. Treating the brain as the entirety of the mind is not scientific fact but philosophical speculation. The relationship between neuroscience and philosophy of mind remains an open and fascinating frontier.
*Note: “Joseph Green” is a pseudonym.
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