Being You: A New Science of Consciousness

by Anil Seth

Living systems are different. Unlike the examples above, living systems actively maintain their boundaries over time – through moving, or sometimes even just through growing. They actively contribute to preserving themselves as distinct from their...

The starting point for the FEP is that living systems, simply by virtue of existing, must actively resist the dispersion of their internal states. By the time you end up as a puddle of undiffer...

For you, or me, or even a bacterium, our internal states are less disordered when we are alive than when we decompose into mush. Being alive means being in a condition of low entropy. Here’s the problem. In physics, the second law of thermodynamics tells us that the entropy of any isolated physical system increases over time. All such systems tend towards disorder, towards a dispersion of their constituent states over time. The second law tells us that instances of organised matter, like living systems, are intrinsically improbable and unstable, and that – in the long run – we’re all doomed.

But somehow, unlike rocks or ink drops, living systems temporarily fend off the second law, persisting in a precarious condition of improbability.

They exist...

equilibrium with their environment, and this is what it means to ‘exis...

According to the FEP, for a living system to resist the pull of the second law it must occupy stat...

For any living system, the condition of ‘being alive’ means proactively seeking out a particular set of states that are visited repeatedly over time,

According to the FEP, this applies across the board. Ultimately, all organisms – not just bacteria – stay alive by minimising their sensory entropy over time, thereby helping to ensure that they remain in the statistically expected states compatible with survival.

For our purposes, we can think of free energy as a quantity which approximates sensory entropy. Crucially, it is also a quantity that can be measured by an

organism – and therefore it is something that the organism can minimise.

Following the FEP, we can now say that organisms maintain themselves in the low-entropy states that ensure their continued existence by actively minimising t...

But what is free energy from the perspective of the organism? It turns out, after some mathematical juggling, that free energy is basically the same thing as sensory prediction error. When an organism is minimising sensory prediction error, as in schemes like predictive processing and active inference,...

living systems have – or are – models of their environment.

(More specifically, models of the causes of their

sensory si...

models are needed to supply the predictions that in turn define prediction errors.

According to the FEP, it is in virtue of having or being a model that a system can judge whether its sensations are (statistically) surprising.

(If you believe that the number 6 you see comes from the roll of a die, you can judge exa...

These deep connections between the FEP and predictive processing make appealing sense. Intuitively, by minimising prediction error through active inference, living systems will naturally come to be in states they expect – or predict – themselves to be in. Seen this way, the ideas of predictive perception and controlled (or controlling) halluci...

Putting all this together, the picture that emerges is of a li...

modelling its world and its body, so that the set of states that define it as a living system keep being revisited, over and over again – from the beating of my heart every ...

Paraphrasing Friston, the view from the FEP is of organisms gathering and modelling sensory information so as to maximise the sensory evidence for their own existence. Or, as I...

It’s worth noting that minimising free energy – sensory prediction error – does not mean that a living system can get away with retreating into a dark and silent room and staying there, staring at the wall. You might think this would be an ideal strategy, since sensory inputs from the external environment will become highly predictable. But it is far from ideal. Over time, sensory i...

expected values: you’re going to get hungry if you stay in the dark room too long. Sensory entropy will start to grow, and non-existence will loom. Complex systems like living organisms need to allow some things to change in order for other things to stay the same. We have to move to get out of bed and make breakfast, and our blood pressure has to rise while doing so, so that we don’t faint. This matches the anticipatory form of predictive control – allostasis – that I mentioned in the previous cha...

FEP addresses the question ‘What are the conditions for the possibility of existence?’

In order for organisms to stay alive they need to behave so as to maintain themselves in the

(low entropy) states they ‘expect’ to be in. A fish swimming above a coral reef, searching for food, is proactively seeking expected sensory states compatible with its continued survival. In general, living systems do this by minimising a measurable approximation to the entropy of these states, which is free energy.

Minimising free energy requires the organism to have, or to be, a model of its environment (which includes the body). Free-energy-minimising organisms then use these models to reduce the difference between predicted and actual senso...

Indeed, given plausible mathematical assumptions, free energy turns out to be exactly the same thing as prediction error. Altogether, this means that the entirety of predictive processing and controlled hallucinations, of active inference and control-oriented...

through the lens of the FEP as flowing from a fundamental constraint on what it means to be alive...

When we unpack the mathematics of the FEP in more detail, we discover that what I really need to do, in order to stay alive, is to minimise free energy in the future – not just in the here and now. And it turns out that minimising this long-term prediction error means I need to seek out new sensations now that reduce my uncertainty about what would happen next, if I did such-and-such.

I become a

curious, sensation-seeking agent – not someone content to self-is...

Once you start thinking about free will, there’s really no stopping.

What is the aspect of being you that you cling to most tightly? For many, it’s the feeling of being in control of your actions, of being the author of your thoughts.

Where did the movement start? In the mind, or in the finger? Did the intention – or her ‘self’ – cause the action, or was the experience of intention a result of perceiving the finger begin to move?

When I experience ‘freely willing’ an action I am in some sense experiencing my self as the cause of that action. Perhaps more than any other kind of experience, experiences of volition make us feel that there is an immaterial conscious ‘self’ pulling strings in the material world. This is how things seem.

In physics and in philosophy, determinism is the proposal that all events in the universe are completely determined by previously existing physical causes. The alternative to determinism is that chance is built into the universe from the ground up, whether through fluctuations in a quantum soup or through some other as yet unknown principles of physics.

From the perspective of free will as a perceptual experience, there is simply no need for any disruption to the causal flow of physical events.

In the early 1980s, at the University of California in San Francisco, the neuroscientist

Benjamin Libet performed a series of experiments on the brain basis of voluntary action which have remained controversial ever since. Libet took advantage of a well-known phenomenon called the ‘readiness potential’ – a small slope-like EEG signal, originating from somewhere over the motor cortex, that reliably precedes voluntary actions. Libet wanted to know whether this brain signal could be identified not only prior to a voluntary action, but before the person was even aware of the intention to make the action.

His experimental set-up, shown in the image opposite, was straightforward. Libet asked his participants to flex their dominant wrist at a time of their own choosing – to make a spontaneous voluntary action, just as Briony does in McEwan’s novel. Each time they did this, he measured the precise time of the moveme...

movement. Crucially, he also asked his volunteers to estimate when they experienced the ‘urge’ to make each movement: the precise moment of conscious intention, the crest of the breaking wave. They did this by noting the angular position of a rotating dot on an oscilloscope screen at the time they experienced the intention to move, and then reporting this position later on. The data were clear. After averaging across many trials, the readiness potential was identifiable hundreds of milliseconds before the conscious inte...

It does seem strange that the readiness potential can be identified so long before the voluntary action. In brain time, half a second is a very long time.

experiences of volition are forms of self-related perception.

There are three defining features that characterise most, if not all, experiences of volition.

The first defining feature is the feeling that I am doing what I want to do.

Although making tea was fully consistent with my beliefs, values, and desires, I did not choose to have these beliefs, values, and desires. I wanted a cup of tea, but I did not choose to want a cup of tea. Voluntary actions are voluntary not because they descend from an immaterial soul, nor because they ascend from a quantum soup. They are voluntary because they express what I, as a person, want to do, even though I cannot choose these wants. As nineteenth-century philosopher Arthur Schopenhauer put it, ‘Man can do what he wills, but he cannot will what he wills.’

The second defining feature is the feeling that I could have done otherwise. When I experience an action as voluntary, the character of the experience is not only that I did X, but that I did X and not Y, even though I could have done Y.