Panpsychism is the doctrine that everything has a mind, or at least a mental aspect. It says that there is no sharp division between us, with our rich mental lives, and the rest of the world. Our minds are just complex forms of something that is present everywhere, and the whole universe – mountains, clouds, asteroids, dust – is infused with mental life. It is a beguiling view, which has appealed not only to poets and mystics but also to those seeking to understand the place of mind in the natural world. Many philosophers, from ancient times through to the early 20th century, have endorsed a version of it.

The view fell out of fashion in the mid-20th century as philosophers increasingly adopted a materialist outlook, which identifies minds with functioning brains. In recent years, however, panpsychism has undergone a philosophical renaissance, and it is now presented at major conferences and debated in mainstream journals. The contemporary form is somewhat different from older versions. It concerns only one aspect of the mind – consciousness – and it focuses on the presence of this aspect at the fundamental physical level.

Modern panpsychists hold that elementary particles such as electrons and quarks have simple forms of consciousness, and thus that everything in the universe is constructed from conscious elements. They claim that complex forms of consciousness in humans and other animals are built up from the simple consciousnesses of the particles that compose their bodies.

If all this sounds like woo-woo to you, then you’ll find plenty of philosophers who agree. In a Twitter exchange, the Canadian neurophilosopher Patricia Churchland remarked that panpsychism is the consequence of knowing next to no science and asked, “What about Pixie dust? Leprechauns? Ghosts?” Yet panpsychists are not simply cranks. Some neuroscientists have proposed similar views, and one of the leading panpsychists, the British philosopher Philip Goff, has hailed the theory as providing the foundations for a new science of consciousness. So let’s look at the case for panpsychism.

The ghost in the machine

Most contemporary philosophers agree that the mind is not something distinct from the brain. There is no ghost in the machine, as the philosopher Gilbert Ryle put it. Rather, talking about the mind is just a different way of talking about the brain and what it does. The idea is that brains are complex control systems that process sensory signals and use the information to regulate behaviour. When we talk about mental states, such as experiences and thoughts, we are referring to states of these control systems, defined by the role they play within them.

Take the experience of smelling a rose. This is a state of the brain (a pattern of activation in certain brain regions) that is caused by a characteristic pattern of signals from receptor cells in the nose and carries information about the presence of roses. It also has a characteristic pattern of effects on other brain systems, producing rose-related memories, associations, beliefs, desires and other psychological reactions.

It is this distinctive pattern of causes and effects that makes it the experience it is – smelling a rose, rather than seeing a blue sky or feeling dizzy. Every experience has its own distinctive profile of causes and effects, as does every other mental state. This view is known as functionalism, since it says that mental states are defined by the function they perform, rather than by the stuff they are made of, and it has been the dominant view in philosophy of mind since the 1970s.

Now, consciousness can also be thought of in this functionalist way. Not all mental states are conscious. Our brains continually register and use sensory information subliminally. Your olfactory system might detect a faint rose scent in the air and trigger a childhood memory of your grandmother’s garden without your being consciously aware of having smelt anything. Sensory information is conscious only when it has the right effects on the rest of the system. According to one account, this involves the information being “globally broadcast” to a range of higher mental systems, including ones for reasoning, decision-making, language, memory and emotion. When this happens, you – the organism composed of all these brain systems – can use the information flexibly, thinking about it, reporting it, recalling it and so on.

How does it make you feel?

From this perspective, consciousness is just another aspect of brain functioning: global information sharing. The American philosopher and cognitive scientist Daniel Dennett speaks of it as “fame in the brain”. But is that all there is to consciousness? Some philosophers say it is not. For the functionalist account seems to miss out something important – the essence of consciousness, its subjective dimension. Information sharing in the brain may be the objective, public side of experience, which can be described by neuroscientists. But, these philosophers argue, there is also a subjective, private side to it – what it is like for the creature undergoing it; how it feels on the inside.

Take pain, for example. Functionalism says that pain is a state of the brain that is produced by stimulation of pain receptors, carries information about bodily damage and produces a range of reactions, both psychological (trauma-related emotions, thoughts, desires and memories) and behavioural (wincing, crying, complaining).

But, the critics say, there is more to pain. There is the actual feel of it, the painfulness; what it’s like to be in pain. This seems to be distinct from the processes mentioned in the functionalist account. We could imagine all those processes occurring – in a robot, perhaps – without there being any subjective feeling at all.

This subjective feel isn’t a matter of what the brain state does, but of what it is like in itself, intrinsically, apart from all its causes and effects, and it is wholly private. With suitable instruments, neuroscientists could detect all the effects a pain state has in your brain, but they could never access its subjective feel.

Similarly for all other conscious experiences: seeing, hearing, tasting and so on. These are brain states which encode information and make it available to other brain systems, but (so goes the argument) they also have an intrinsic feel to them: what it’s like to see a sunset, hear birdsong, taste lemon juice and so on. Philosophers refer to this intrinsic “what-it-is-likeness” of experience as its phenomenal feel.

Solving the "hard problem"

So, we have two different conceptions of consciousness: an objective functional one (often called access consciousness) and a subjective phenomenal one (phenomenal consciousness). As we have seen, the functional form is not particularly mysterious. But phenomenal consciousness is another matter. How does a brain state come to have a subjective aspect, an intrinsic phenomenal feel, undetectable from the outside? There may not be a ghost in the machine, but there seems to be some ghostliness in it all the same.

This problem was given particularly forceful presentation in the mid-1990s by the Australian philosopher David Chalmers, who famously dubbed it the “hard problem of consciousness” (as opposed to the easy problems of explaining access consciousness).

Many theories of phenomenal consciousness have been proposed, but all have serious weaknesses. Some seek to explain phenomenal feel in terms of properties of the brain, which is implausible, while others hold that there are basic laws of nature linking brain states with phenomenal feels, which seems arbitrary. It is this history of failure that has inspired some researchers to turn to panpsychism.

Panpsychists point out that, in general, complex things are built up out of simpler ones. Brain states are complex structures built out of elementary particles. The phenomenal feels of these brain states (the way they feel to the person whose brain it is) are also complex, so isn’t it plausible that these, too, are built out of simpler elements?

The most elegant view, panpsychists argue, is that elementary particles themselves have a very basic kind of phenomenal feel, and that the rich phenomenal feels of our brain states result from combining the feels of the particles that compose them. This is more plausible, they argue, than supposing that rich forms of phenomenal consciousness pop into existence fully formed in the brains of living creatures.

Of course, panpsychists don’t claim that elementary particles are conscious in the functional sense; they don’t think electrons have tiny brains which process sensory information and use it to control their behaviour. They claim only that particles have a basic kind of phenomenal consciousness – an intrinsic phenomenal feel. And this does seem conceivable. A thing need not do anything in order to have an intrinsic aspect; it just has to exist, and elementary particles do that all right.

There is another consideration in favour of this view, which many see as a clincher. It comes from reflection on physics itself. Physics aims to describe the basic constituents of the universe, such as electrons and quarks. But, panpsychists point out, it doesn’t tell us what these things are, only how they behave. It describes them as having mass and charge and so on, but this is merely a way of describing how they interact with other particles and forces. (Mass, for example, is a disposition to resist acceleration.) We don’t know what the fundamental particles are like in themselves, intrinsically.

Here, panpsychists say, is where consciousness comes in. For, they say, we do know the intrinsic nature of one aspect of physical reality: the bit inside our own skulls. When we attend to our experiences, we are directly aware of what our brain states are like in themselves, intrinsically, apart from all the effects they have. Panpsychists take this as a model for the intrinsic nature of physical things generally. Our best hypothesis, they say, is that electrons, quarks and other elementary particles are really tiny blobs of phenomenal feel: micro-consciousnesses.

We arrive at the following picture. Elementary particles are actually micro-consciousnesses. They behave in the way physics describes, and they interact and combine to create all the complex physical structures in the universe, including brains. In parallel, their phenomenal feels combine to create the complex phenomenal feels brains possess. It’s a neat story, which not only solves the “hard problem” but also explains what the intrinsic nature of matter is. What’s not to like?

A lot, actually. For one thing, not all philosophers agree that elementary particles must have an intrinsic nature of some kind. Some think that physics tells us all there is to know about them. But let’s set that aside and focus on the panpsychist picture itself.

Inside the human brain

Panpsychists acknowledge that their view faces problems. The most discussed of these is the combination problem. How do the trillions of micro-consciousnesses in my brain combine to form my consciousness? Can we even make sense of the idea of distinct consciousnesses fusing together? Since we have no idea what the consciousness of particles is like (only the particles know!) and we know nothing of the method by which they combine, we’re totally in the dark here. As the philosopher Yujin Nagasawa puts it, we’re in the position of someone trying to bake a cake without any idea of what the ingredients are or what the recipe is.

There are more problems. For example, when do micro-consciousnesses come together? Panpsychists claim that the micro-consciousnesses of the particles in living brains combine. But why would they be the only sets of particles that do so? What about those in other bodily organs? Or in computers, trees, rocks or stars? We assume these things don’t have complex consciousnesses, but how do we know?

If brains aren’t special in being the only things that possess consciousness at all, why should they be special in being the only things that possess a complex consciousness? Maybe all physical structures have a complex consciousness formed by the union of the micro-consciousnesses of their particles. Wouldn’t that be the most elegant view? We have no way of knowing, of course, since we cannot detect the intrinsic nature of things.

There is a deeper problem, too. If the phenomenal feel of experience is the intrinsic nature of our brain states, then how are we aware of it? To be aware of something, we need a sensory system of some kind that can detect it. The brain probably has self-monitoring systems that can detect the experiences that are occurring within it. Experiences are brain states, and monitoring systems could detect them by sensing their objective physical characteristics, including the effects they have on the rest of the brain.

But by what means could a monitoring system peer into the intrinsic nature of these states – what they are like subjectively, on the inside? How could one part of the brain see into the intrinsic nature of another part? We are faced with the bizarre possibility that we don’t know what our own experiences are like. My visual cortex may know what it’s like to see red, but I don’t! The absurdity of this conclusion suggests that something has gone seriously wrong somewhere.

Of course, panpsychists will reply that we don’t need self-monitoring systems to be aware of the phenomenal feel of our brain states. The feel, they will say, is what the brain states are like in themselves, and we are aware of it simply by being in those states. However, it is hard to make sense of this suggestion. It’s one thing to be in a certain state and another to know that you are in it, and panpsychists offer no explanation of how we get from one to the other.

The real lesson of the panpsychist renaissance

You have probably guessed by now that I’m not convinced by panpsychism. In fact, I think the real lesson of the panpsychist renaissance is a negative one. If the search for a theory of phenomenal consciousness leads us to panpsychism, then we should question whether phenomenal consciousness really exists. Maybe functionalism doesn’t leave out anything after all.

It’s true, of course, that the functionalist picture seems to leave out something, but maybe that’s a sort of illusion, due to the fact that we are not aware of the complexity of the processes involved in conscious experience. Perhaps, when we talk about what an experience feels like, we are referring, in an indistinct way, to the complex pattern of psychological effects it produces in us – effects which, unlike phenomenal feels, can be detected by other brain systems. And as neuroscience tells us more about these effects and the mechanisms that make us sensitive to them, perhaps we shall lose the sense that there is anything more to consciousness.

Rather than heralding a new science of consciousness, panpsychism may be the last gasp of a prescientific view of what consciousness is.

This piece is from the New Humanist spring 2022 edition. Subscribe here.