What's Going On in Your Head? The Puzzle of Minds and Brains

You’re sitting in class. Your friend passes you a note. You read it, and suddenly you feel annoyed—then you decide to write something back, and your hand moves to pick up a pencil.

That chain of events is so ordinary you barely notice it. But if you stop and think about it, something really strange is happening. Something in the world—ink on paper—gets transformed into something in your mind—a thought, a feeling, a decision. And then that something in your mind somehow makes your body move.

How does that work? How can a thought—something that seems to have no physical stuff, no weight, no location—cause your arm to move? And how can something physical, like ink on paper, cause you to have a thought in the first place?

Philosophers have been wrestling with this for centuries. And one of the most interesting and frustrating answers came from a philosopher named Donald Davidson. His view is called “anomalous monism,” which is a fancy way of saying: there’s only one kind of stuff in the universe (monism), and mental things are weird exceptions to the rules (anomalous). Let’s see what he meant.

Three Things That Seem True But Can’t All Be True

Davidson started by noticing that we believe three things that seem obvious, but that actually pull in opposite directions.

First: Minds and bodies affect each other. You stub your toe (physical event), and you feel pain (mental event). You decide to say something (mental event), and your mouth moves (physical event). This seems undeniable. Philosophers call this the interaction principle.

Second: When one thing causes another, there’s a law that connects them. If striking a match causes it to light, there’s a law of physics that explains why: friction creates heat, heat ignites the chemicals, etc. The law doesn’t have exceptions—every time the conditions are right, the same thing happens. Philosophers call this the cause-law principle.

Third: There are no strict laws about mental things. You might think “if someone wants X and believes Y will get them X, then they’ll do Y.” But people don’t always act on what they want. They change their minds. They get distracted. They act irrationally. There just aren’t any exceptionless laws about what people will think, feel, or do. Philosophers call this the anomalism principle.

Here’s the problem. If minds and bodies affect each other (first claim), and causes always fall under laws (second claim), then there must be laws connecting mental events to physical events. But the third claim says there are no such laws. That’s a contradiction. Something has to give.

Davidson’s solution was clever and strange. He said: the laws do exist—but they’re not mental laws. They’re physical laws. And the only way that works is if every mental event is also a physical event.

The Escape Hatch: How You Describe Things Matters

To understand Davidson’s move, you need to understand a distinction he thought was crucial: the difference between causation and explanation.

Imagine you’re at a soccer game and someone kicks the ball into the goal. Here are two ways to describe what happened:

“The ball was kicked by a 12-year-old in a red jersey.”
“The ball was kicked by a kid who was trying to impress his dad.”

Both descriptions pick out the same event—the same kick. But they explain different things. The first tells you something about the physical facts (who did it, what they were wearing). The second tells you something about the person’s reasons.

Here’s the key point: causation doesn’t care how you describe things. If the kick causes the ball to go into the net, it doesn’t matter whether you call it “the kick” or “the thing that impressed the dad”—the causal connection is the same. But explanation does care how you describe things. Saying “the ball went in because a 12-year-old kicked it” is a good explanation. Saying “the ball went in because someone was trying to impress their dad” might be a bad explanation—it doesn’t tell you anything about the physics of the ball’s trajectory.

Davidson’s move was to say: when a mental event causes a physical event, the causal relationship is covered by a physical law—but the explanation might be given in mental terms. So there are strict laws covering what happens, but those laws are physical laws, not mental ones. The mind doesn’t have its own laws; it borrows them from physics.

What Makes Mental Things Special?

But wait—why can’t there be mental laws? If every mental event is also a physical event, couldn’t we just discover laws that connect mental descriptions to physical descriptions? Like: “whenever someone’s brain is in state X, they believe it’s raining”?

Davidson thought no. And his reason has to do with what makes mental things mental in the first place.

Think about what it means to have a belief or a desire. If you believe something, it’s supposed to be true (or at least you think it is). If you want something, it’s because you see it as good in some way. Mental states are connected to each other by reasons, not by physical forces. If you believe it’s raining and you want to stay dry, you’ll take an umbrella—not because there’s a law of physics that makes you do it, but because it makes sense to do it.

This is what Davidson called the “normative” or “rational” character of the mental. Mental states are held together by logic and rationality, not by cause and effect. And that, he thought, makes them impossible to capture in strict laws.

Here’s an example. Suppose a psychologist tried to formulate a law: “If a person wants A, and believes that doing B will get them A, then they will do B.” Sounds reasonable. But what about the person who wants to eat cake, believes that eating cake will make them happy, but doesn’t eat the cake because they’re on a diet? The law fails. You’d need to add another belief: “they also believe that not eating cake is more important.” But that’s just pushing the problem down the road. There’s always a way the person could fail to act on their desires—because they change their mind, because they’re irrational, because other desires get in the way.

No matter how many conditions you add, you can never close off all the possibilities. Mental life is just too flexible, too connected to everything else you believe and want. That’s what Davidson meant by saying there are no “strict” laws for the mental.

So What Are We?

If you put all this together, Davidson’s picture looks like this:

Every mental event is identical to some physical event. Your thought about your friend’s note is some pattern of neurons firing in your brain. There aren’t two things happening—a mental thing and a physical thing—just one thing that can be described in two ways.

But mental descriptions and physical descriptions don’t line up neatly. You can’t predict what someone will think just by looking at their brain, and you can’t predict what someone’s brain will do just by knowing what they’re thinking. The two vocabularies—mental and physical—are both real and both useful, but they don’t map onto each other in any law-like way.

Mental events really do cause physical events. Your decision to write back really does make your hand move. But the law that covers that causal connection is a physical law—about neurons and muscles and chemistry—not a mental law about reasons and decisions.

This is a deeply strange view. It says that minds are real, mental causation is real, but there’s no science of the mind that works like physics works. Psychology will never be like chemistry. You’ll never have a formula that tells you exactly what someone will think or do.

Does This Make Minds Impotent?

A lot of philosophers have objected to Davidson by saying: if the real causal work is being done by the physical side, then the mental side is just a “tag-along”—it seems like your thoughts and feelings are just along for the ride, not actually doing anything.

Imagine you’re playing a video game. The character on screen jumps because you pressed a button. Now imagine someone says “the character jumped because the pixels turned yellow for a split second.” That’s a true description, but it’s a weird one. The real explanation is that you pressed the button. The pixel-color description picks out the same event, but it doesn’t explain anything.

Critics of Davidson say the same thing about his view. Sure, your decision to write back is identical to some brain event. But if the causing is done by the brain event described as physical, then your decision described as a decision isn’t really doing any causing. The mental description is just a passenger.

Davidson had a response: causation doesn’t care how you describe it. If your decision (which is a brain event) causes your hand to move, then your decision as a decision causes your hand to move. The causation is the same regardless of which label you use. But his critics weren’t satisfied. They wanted to know whether the mental properties themselves—the fact that the brain event is a decision, not just a bunch of neurons firing—make any difference to what happens. And that’s harder to answer.

Why This Still Matters

Nobody really knows whether Davidson was right. Philosophers still argue about it. But his view captures something important that other views miss.

If you think minds are just brains (which many scientists and philosophers do), you have to explain how thoughts can be real and meaningful, not just illusions. Davidson’s view gives minds a real place—they’re not just brain noise. But it also accepts that the physical world is governed by laws in a way that the mental world isn’t.

If you think minds are separate from brains (like the old “ghost in the machine” idea), you have to explain how they interact at all. Davidson’s view avoids that problem by saying they’re not separate—they’re the same thing, just described differently.

And if you think there’s some middle ground—like psychology can have its own laws, just not as strict as physics—you have to explain why those laws always seem to have exceptions. Davidson’s view gives a reason: because rationality doesn’t work like causation.

So next time you read a note and feel annoyed and decide to write back, you’re participating in one of philosophy’s hardest problems. How did that ink on paper become a thought? And how did that thought move your hand? Davidson’s answer was: the same way anything causes anything else. It’s just that when we talk about thoughts, we’re talking about it in a way that doesn’t fit into neat formulas. The mind is a real part of the world—but it’s the part that refuses to be captured by rules.

Key Terms

Term	What it means in this debate
Anomalous monism	The view that there’s only one kind of stuff (physical), but mental descriptions of that stuff don’t obey strict laws
Interaction principle	The idea that mental events and physical events cause each other
Cause-law principle	The idea that whenever one event causes another, there’s a strict law that covers that relationship
Anomalism principle	The idea that there are no strict laws involving mental events
Strict law	A rule about what causes what that has no exceptions
Token-identical	A particular instance (token) of a mental event is the same thing as a particular instance of a physical event

Key People

Donald Davidson (1917–2003): An American philosopher who spent most of his career teaching at the University of Chicago, Stanford, and UC Berkeley. He argued that minds are real and cause things, but can’t be captured by laws.

Things to Think About

If every thought you have is a brain event, does it matter whether we call it a “thought” or a “brain event”? Should it matter?
Davidson said there can’t be strict laws about what people will think or do. But what about things like: “if someone is really thirsty and sees water, they’ll want to drink it”? Is that a law? Does it ever fail?
If mental descriptions don’t do any real causal work—if the physical stuff is what actually makes things happen—does that mean your sense of “choosing” to do something is an illusion?
Could a super-advanced brain scanner ever predict exactly what you’ll decide before you decide it? If yes, does that mean your decision wasn’t really free?

Where This Shows Up

In science fiction: Stories about uploading minds to computers, or creating artificial intelligence, have to deal with whether mental states can be reduced to physical ones. Davidson’s view says they can’t—there’s an irreducible difference between how we describe mental life and how we describe physical systems.
In debates about free will: If mental events are just physical events under another description, then determinism in physics might imply determinism in mental life. Davidson’s view complicates this by saying mental descriptions don’t obey the same kind of rules.
In psychology and neuroscience: Most researchers assume there are regularities in mental life that can be studied scientifically. Davidson’s view challenges whether those regularities can ever be exceptionless laws.