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Key Takeaways
- At Big Think’s 2025 live event at Oxford University, The Mystery of Consciousness, Jonny Thomson interviewed bestselling author and neuroscientist Anil Seth about the science of consciousness.
- Seth is a physicalist, which means he thinks the brain can fully explain what happens in the mind.
- If physicalism is true, then we could hypothetically read people’s minds by reading their brains. Here’s how close we are to that reality.
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In philosophy, physicalism is the idea that everything can be explained in physical terms. Whether through atoms, electrons, quarks, fields, or other physical processes, physicalism holds that every phenomenon ultimately depends on the physical world.
In the philosophy of mind, this means that everything about the mind can, in principle, be explained by the physical processes of the brain. We don’t yet know all the details, but physicalism maintains that a complete explanation is possible.
In September 2025, I interviewed neuroscientist and bestselling author of Being You, Anil Seth, about the mystery of consciousness. Seth is a physicalist, and so I asked him this question: “With the current state of consciousness science at the moment, if we were to give everybody in this room here some kind of brain scan, with what degree of certainty could you infer what is going on in people’s minds?”
In his book and in his talk, Seth argues that we can divide “consciousness” into three elements: consciousness level, consciousness content, and consciousness selfhood. So here is what we know so far about each of those. Here is the science of mind-reading.
Consciousness level
Your consciousness level is how conscious you are. At one end, there is complete unconsciousness. At the other end, you have alertness, awareness, and focus — right now, probably. And then we have sleep, fatigue, intoxication, comas, and so on, all along the spectrum in between. According to Seth, we can tell a lot about one’s consciousness level.
“If everyone was wearing an EEG and the data was good, it’s kind of not too difficult to predict whether you are conscious or not, that can be done. Human beings in conscious states; their brain activity is relatively predictable in some ways. You have lots of sort of fast oscillations going on in various frequency bands, and there are the more sophisticated ways of measuring this. And when you fall asleep, you see very distinct patterns when you fall asleep and you’re not dreaming, same under anesthesia.”
“[…] But even then, there are weird edge cases; there are people who have brain injuries, for instance, and then it might be harder. If someone has something called the “vegetative state” or the “wakeful unawareness state,” they might look awake, but they also look like there’s nobody at home. And then it becomes a much more tricky problem to predict, [to] tell whether there’s any consciousness going on inside.”
Consciousness content
Content is what you are conscious of. If your phone rings, you focus on it. If you have a toothache, your mind keeps pulling back to it. If you look at your hand right now, your hand is part of the “content” of your consciousness.
“When it comes to predicting what you are conscious of, it’s much, much harder,” Seth says. “But there is this growing research field of ‘brain reading’ now. This is taking somebody’s brain signals, measuring them somehow, and then trying to predict what they are thinking and what they are experiencing.”
“This is now one of those things that’s moving from science fiction into science reality. And there are some already, really, to me, impressive examples of this that are usually used in clinical cases. For instance, people who are paralyzed: You can now begin to read out their movement intentions, so you can help them control robots or even maybe even guide their own arms by stimulating muscles, decode what they want to say, so they can regain the ability to communicate in some cases. These algorithms that do these predictions are not perfect, and so, as we stand now, I don’t think we’d be able to predict with great certainty what you were all thinking right here and right now, but I think that that might change.”
Consciousness selfhood
If “level” is how switched-on you are, and “content” is what fills the spotlight of awareness, then “selfhood” is the sense that you are the one having the experience. Seth argues that this, too, can be traced in the brain — not to a single “self spot,” but to a set of interacting systems that generate the feeling of being an embodied, continuous subject.
At a basic level, there is bodily self-consciousness. The brain is constantly stitching together signals — sight, touch, balance, proprioception — to maintain the feeling that you inhabit this body. When those signals are disrupted, the self can slip. For example, lesions to the right temporoparietal junction have long been linked to out-of-body experiences.
A bit up from this, there is the inner, reflective self — the part engaged in autobiographical memory, introspection, and daydreaming. This mode is linked to the default mode network (DMN), a set of regions including the medial prefrontal cortex and posterior cingulate. The DMN brightens on an fMRI when someone thinks about their personality or recalls a personal memory, and it quiets when attention shifts outward to a task.
Finally, the brain also marks the recognition of self — your own face, voice, or name. Seeing one’s own face activates right-hemisphere regions such as the inferior frontal gyrus and inferior parietal lobule. Hearing your own name or voice engages self-processing areas like the temporoparietal junction and precuneus. These consistent patterns mean that, in practice, if you were lying in a scanner, an observer could often tell when your brain was responding to yourself.
The ethics of brain reading
So, in short, we’re not quite there but are very close to a kind of functional “brain mapping.” We can reasonably measure the level of consciousness someone is experiencing, and we can infer or make meaningful guesses about what people are conscious of. We can isolate the category or genre of content, but not necessarily the specific tokens within that category.
Of course, all of this fails to appreciate the ethical issues lurking underneath. Even though we can or might be able to brain-read, should we? Why would we want this technology? Of course, law enforcement agencies could use it; employers, advertising agencies, and tech companies would love it. But is that a good reason? Here is what Seth thinks:
“This is actually a very dangerous technology. We think we have freedom of speech, which is arguable in some cases, but very few places have freedom of thought. And once you have brain imaging things that are predicting what you’re thinking, then you’ve lost that last bastion of privacy because once you get inside the skull, there’s nowhere else left.”
In other words, if anyone, anywhere could see all the strange, private, dark, and sordid thoughts that go through your head, what would that mean? Could you be imprisoned or under watch for having certain socially unacceptable — or someday “illegal” — thoughts?
The thought police have long been the subject of Orwellian science fiction. But what Seth teaches us is that it might not be as far away as we think. And when we move one step closer to a dystopia, we need philosophy, debate, and caution before we reach a place we can’t come back from.
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