Aristotle famously characterized human beings as rational animals. He also thought the heart was the seat of intelligence and that the brain was basically a radiator for cooling the blood, so perhaps we should not be too quick to take his taxonomy of human faculties at face value. Patricia Churchland would agree, though for reasons that go considerably further than correcting ancient Greek anatomical errors.
Churchland is a Canadian philosopher who, starting in the 1980s, decided that philosophy and neuroscience had been living in separate apartments for far too long and that it was time they moved in together. She called the resulting cohabitation “neurophilosophy,” and she is widely considered its founding mother. Her core argument, put plainly, is this: the vocabulary philosophers and ordinary people use to describe the mind, words like “soul,” “free will,” “belief,” and “desire,” is scientifically empty. It refers to nothing neurobiologically real. And if it refers to nothing real, we should probably stop using it.
This, as you can imagine, went over pretty well with everyone.
What Is Neurophilosophy?
Before we get into why Churchland’s project is so controversial, it helps to understand what it actually is. Neurophilosophy is a strong claim that the right way to understand the mind is to look at what the brain is actually doing, and then rebuild our theory of mind from the ground up using that information.
If we take neuroscience seriously as a guide to what the mind actually is, we may discover that many of our ordinary mental concepts simply don’t carve nature at its joints. Let’s consider “belief.” When you say you “believe” that the coffee is too hot to drink, you are implicitly committed to the idea that there is some discrete, identifiable mental state inside you with a specific content that causes certain behavior. But when neuroscientists look inside your skull, they don’t find anything that obviously corresponds to that picture. They find patterns of activation distributed across neural networks, not tidy little boxes labeled “beliefs” and “desires.”
Churchland’s conclusion is that folk psychology, the commonsense theory of mind you and I use when we explain each other’s behavior in terms of beliefs, desires, and intentions, is a theory. And like any theory, it can be wrong. She thinks it probably is wrong, and that neuroscience will eventually replace it with something more accurate, the way chemistry replaced alchemy and astronomy replaced astrology. If you are currently insulted by the comparison of your inner mental life to alchemy, I’m afraid that is very much the point.
There Is No Soul, and Also No Belief
Churchland’s view is a version of what philosophers call “eliminative materialism.” The “materialism” part just means the mind is physical, which most people accept at some level these days. The “eliminative” part is where things get spicy. It means that certain mental categories we currently take seriously will eventually be eliminated from our best scientific picture of the world, not reduced to neural states, but simply dropped.
The soul is the obvious target here. Virtually everyone in the scientific community already agrees that “soul” picks out nothing in the physical world. But Churchland’s more provocative suggestion is that concepts like “belief,” “desire,” and even “pain” in its ordinary folk-psychological sense may be in the same boat. They are part of a theory that has served us reasonably well for coordinating social life, but that will ultimately prove too crude to capture what is actually happening in the brain.
This makes eliminative materialism extremely unpopular (and not just with religious people). It is also unpopular with philosophers who have spent entire careers analyzing the concept of belief, linguists who study how mental terms work in language, and basically any ordinary person who has ever been asked to describe their inner life and would prefer not to be told that their inner life is a theoretical fiction. That last group includes, I think, most people. In which case, my condolences.
The Objection
The most immediate objection to Churchland’s view goes something like this: “But I clearly have beliefs and desires. I know I believe it is raining right now. I know I want a cup of coffee. How could neuroscience possibly tell me I’m wrong about the contents of my own mind?”
This is a fair objection, and it deserves a fair answer. Churchland’s response is that introspection, our ability to report on our own mental states, is not infallible. There is now quite a lot of neuroscientific evidence that our introspective reports are frequently confabulated after the fact, that our brains make decisions before we are consciously aware of them, and that the story we tell ourselves about why we did something is often a post-hoc rationalization rather than an accurate causal account. The fact that something seems a certain way from the inside is not decisive evidence that it really is that way.
This is a such a fascinating point. It is also the kind of point that makes you feel vaguely nauseated once you really sit with it. The idea that your confident sense of your own beliefs and motivations might be a story your brain is telling you rather than a direct readout of what is actually happening inside you is philosophically exhilarating and personally destabilizing, which is exactly the combination that makes philosophy both valuable and universally dreaded.
So What Do We Replace It All With?
A reasonable follow-up question is: if we are supposed to throw away all our folk-psychological vocabulary, what exactly replaces it? Churchland’s answer is that we don’t know yet, and that this is fine. Science routinely works in the gap between abandoning an old framework and fully articulating the new one.
What neurophilosophy can do in the meantime is start building bridges. Churchland’s own work has explored how neuroscience might inform our understanding of moral cognition, decision-making, and social behavior. Her 2011 book Braintrust argues that our moral sense is rooted in neural mechanisms that evolved to support social bonding in mammals, and that oxytocin and related neurochemicals are doing a lot of the philosophical heavy lifting that we used to attribute to Reason, God, or the Moral Law.
A lot of philosophers feel that explaining where our moral intuitions come from does not tell us which ones are correct. Churchland is skeptical that the question “which intuitions are correct?” has an answer that floats free of biology entirely. This disagreement has been ongoing for several decades now.
Conclusion
Churchland’s neurophilosophy is, at its core, a very simple idea with very radical implications: if you want to understand the mind, you have to look at the brain, and if what you find in the brain doesn’t match your pre-existing philosophical vocabulary, then the vocabulary has to go. Au revoir ! The soul, the will, the self as a unified rational agent, these may all turn out to be useful fictions rather than scientific categories.
This is either a liberating insight or an intolerable affront to human dignity, depending on who you ask. Most people, in my experience, oscillate between the two depending on how the argument is going for them at any given moment. Which is, come to think of it, exactly the kind of behavioral pattern that neuroscience is getting increasingly good at explaining, even if we haven’t quite agreed on what to call it yet.