British neuroscientist, Sussex, born 1972

Anil Seth

The brain does not passively receive the world. It predicts it, and what we perceive is its best guess: a controlled hallucination, kept in check by the senses. The deepest predictions are about the body itself, which is why consciousness may be bound up with being alive.

The view

Seth directs research on consciousness at the University of Sussex, and his book Being You (2021) brought his ideas to a wide audience. He works within the framework of predictive processing, developed by Karl Friston, Andy Clark and others, building on Hermann von Helmholtz's nineteenth-century idea that perception is a kind of unconscious inference. The brain constantly generates predictions about the causes of its sensory signals, and uses the mismatch, the prediction error, to update them. What we experience is the prediction, not the raw input.

Seth adds two things. First, perception of the world is a "controlled hallucination": like a dream, but reined in by the senses. Second, the most fundamental predictions are about the inside of the body, its heartbeat, breathing, temperature and chemistry. These predictions are not mainly for knowing but for control, keeping the body alive. Emotions and the sense of being a self are, on this view, perceptions of the body's state. He calls this the beast machine theory: we are conscious because we are living, self-regulating creatures.

The argument

We do not perceive the world as it is, but as it is useful for us to perceive it. After Seth, Being You (2021)

Seth proposes setting aside the hard problem in favour of what he calls the real problem: explaining, predicting and controlling the properties of conscious experience in terms of brain mechanisms. Why do colours look like surfaces? Why does the self feel unified? Why do emotions feel like this? Progress on these, he thinks, may dissolve the hard problem as progress in biology dissolved the mystery of life. The figure shows prediction at work. Look at the black-and-white blobs, then see the original, then look again.

Once you have seen the original, the blobs organise themselves into a face and you cannot unsee it. Nothing on the screen has changed; your brain's predictions have. This is Seth's point in miniature. What you experience depends on what your brain expects, not just on what arrives at the eye.

Where he meets Dennett

Further than the "far side" label suggests. Seth rejects dualism and panpsychism, works by building and testing mechanistic models, and agrees that much of what seems given in experience is constructed by the brain. "Controlled hallucination" and "user illusion" are close cousins. Both see the self as a construction rather than a thing, and both value thought experiments only when they lead to new questions for science.

Where they part

Seth does not call experience an illusion. Experience is real, he says, and the task is to explain its features, not to explain away our belief in it. He also doubts functionalism, which puts him further from Dennett than the allies on this site. If consciousness is rooted in the regulation of a living body, then a computer, however intelligent, may not be conscious at all. Seth has argued that conscious AI is unlikely and that it would be dangerous to build machines that merely seem conscious. Dennett expected intelligence and consciousness to come as a package, in any substrate, and thought "being alive" mattered only because of what living systems do.

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Further reading

• Anil Seth, Being You: A New Science of Consciousness (Faber, 2021).
• Andy Clark, The Experience Machine: How Our Minds Predict and Shape Reality (Allen Lane, 2023).
• Lisa Feldman Barrett, How Emotions Are Made (Macmillan, 2017): predictive processing and the body.
• The neuroscience of consciousness, Stanford Encyclopedia of Philosophy.