Of all the sciences, physics has been seen as the key to understanding everything. As Feynman said, “physics is the fundamental science.” But in this article, one of the world’s leading physicists, George F. R. Ellis, who collaborated with Stephen Hawking in work on spacetime’s geometry, argues that much of reality extends far beyond physics. Both complex objects like biological organisms and abstract entities like the rules of chess influence the world in ways that cannot be predicted by studying their simple physical constituents. Science, Ellis insists, is far richer than any single framework can ever capture.

1. Abstract Causation

A remarkable feature of the world is the existence of abstract causation – the way that non-physical entities can cause physical effects via the workings of the human mind, or by the functioning of digital computers we create. The reality of abstract causation shows that physics has limits: there are some things physics cannot explain. Consider the rules of chess. They control the physical movement of chess pieces on chess boards throughout the world. But they are not physical things. They are not made of wood or stone or steel, and they don’t involve electrical or magnetic forces acting on the chess pieces. So how is this control possible?

The rules of chess are socially agreed rules of play that are arrived at by a trans-generational process of negotiation (they emerged at the end of the 15th century). Once they are agreed, they instruct all players around the world what moves are and are not allowed; for example, the queen can move any number of vacant squares horizontally, vertically, or diagonally, but cannot jump as a knight can. This is learnt by all chess players, and through brain plasticity, stored in the detailed patterns of neural connections in their brains. Action potential spike trains in these neural networks shape their thoughts as a player considers her next move, in the light of her game strategy shaped by a study of many games played by others in the past. Finally, a chess piece is moved by her muscles in accord with the rules of chess; that’s how the rules attain their causal powers. We do not know in detail how particular thoughts, such as those about the rules for moves by a Queen, are stored in the brain’s neural networks, or represented by these spike chains. Nevertheless we do know that this happens.

I claim that this is an example of abstract causation. A reductionist, who thinks that physics can ultimately explain everything, will respond:

Hold on – in the end the rules of chess are implemented physically, for example through electrons moving in the brain as just mentioned. So they are nothing but particular brain states at the physical level – configurations of electrons and protons that change over time – just another example of how physics controls everything.

However this is not correct. That is how the rules are implemented in one particular case. But the rules of chess can be spoken about, and so represented by sound waves; printed on a page, and so represented in printed text; explained in a video; talked about in a chess class; or represented in algorithms in a chess-playing computer. The rules of chess can exist in these multiple forms, not just in individual minds/brains. Furthermore, in response to the claim “they are nothing but brain states,” then the issue is: whose brain? Gary Kasparov’s? So the rules of chess will cease to exist when he dies? This is obviously not correct. They are represented in the brains and minds of millions of chess players. They are not identical to their representation in any individual brain.

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Physics does not determine what happens: the mind/brain does

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So what are they? They are abstract entities, defined as the equivalence class of all these representations. That is, they are the set of all representations of how chess pieces can move that correctly represent the rules stated by the International Chess Federation. This is not a physical entity, it is abstract. It gains its causal powers when local chess clubs and their members agree to abide by these rules. The causal efficacy of the mental states is then grounded by their being realised by physical entities: the flows of electrons in neural networks in the brain. Thus it is a clear case of abstract causation: abstract entities having physical effects.

Physics does not determine what happens: the mind/brain does, where the mind is the conscious state involving thoughts and qualia that is realised through flows of electrons in the physical brain. The overall causal chain is that the players’ mind/brain considers the rules of chess and the state of play, and on this basis decides what move to make next. She then makes the move through her agency: causing specific muscle states in her hand to be activated as desired. This causes chess pieces to move on chess boards according to the rules of chess, or images of chess pieces on a computer screen to move similarly. Physics enables this to take place. Thoughts about chess moves, and their implications for the way the game will develop, determine the specific outcomes.

Now there is a large literature out there, for example the paper “Real Patterns” by Daniel Dennett, saying that this is incorrect. Laplace’s Demon, given total knowledge about a brain’s initial micro-state – the position of every proton and electron in the brain at a time t₀ – would be able to determine all the brain’s future states, and hence all future thoughts, by simply applying the laws of physics to the initial micro-state. Hence the brain macro states – thoughts about chess moves and strategies – are powerless: they are epiphenomena that go along for the ride determined by the underlying physics.

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However this viewpoint ignores an essential fact: we are open systems. New information is impacting on our brains from the outside every second. Our brain simply does not have the basis to know what that information will be: it depends on external data not available to Laplace’s Daemon. It is not included in the initial micro-state of the brain. In the case discussed above, the chess player makes her moves in response to the moves made by her opponent – which she does not know until they happen.

The reductionist response is:

But Laplace's Demon knows the positions of all the protons and electrons (or whatever the fundamental particles are) in the entire universe at time t₀, not just a single person's brain. So Laplace's Demon will be able to predict all future impacts on the brain from outside. So I don't see why Laplace's Demon won't be able to predict all future states of the brain, using its knowledge of the laws of physics in combination with its knowledge of the total state of the universe at t₀.

This response conveniently omits to mention when the time t₀ is to be chosen. At the start of inflation? Of the Hot Big Bang era? At the time of the decoupling of matter and radiation? For convenience, I’ll assume the latter. Then the data for how the opponent moves next in the chess game is supposed to be somehow encoded in the data on the Last Scattering Surface (LSS), which has temperature fluctuations as shown in Figure 1 (red and yellow are hotter, blue is colder).

Figure 1: The fluctuations in the temperature of the Cosmic Microwave Background Radiation (CMBR) on the Last Scattering Surface (LSS) at a level of 1 part in 10⁵. Credit: NASA.

In essence, the claim is that detailed information about both the opponent’s existence and next chess move is somehow coded into this data. But that’s absurd, for two reasons. 

Firstly, there is no conceivable mechanism whereby such details about the opponent’s movement could be coded on the LSS in some form, and then subsequently lead to changes in the chess player’s brain through brain plasticity. Developmental processes taking place in our brain do not work that way. 

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 Secondly, suppose that, for the sake of argument, we ignore this overwhelming objection. The proponent of such a view then has to explain how the data got there in the first place. We already understand in depth the processes that lead to  the fluctuations on the LSS: they are clearly stated in Jim Peeble’s recent book. None of the processes described there are remotely like something that could produce a coded version of the rules of chess, and a plan for the next move in a chess game. The view supposes there is kind of some demiurge that likes to play chess, knows the rules of chess, and puts the details of such a move in coded form on the LSS, overwriting the data already there. In the end, this is a sophisticated but unbelievable form of Intelligent Design.

That whole reductionist literature is a classic example of how one can get misled by not taking context into account. The underlying physics is doing the causal work as instructed to do so by the thoughts in the brain – by the functioning of the mind. It works out the next move on the basis of a knowledge of chess strategies and past games played, and an understanding of probable consequences of any specific move made in the present context. Mental states are essential to this process. The various kinds of downward causation from the brain macro-state to its micro-state that enable this to work are well understood. In essence they are the four kinds of causation identified long ago by Aristotle: efficient, formal, material, and final causation.

There are many other examples of abstract causation, apart from the rules of other games such as cricket and tennis and baseball. They include traffic lights that control traffic movements by changing colour from red to green; signs on a wall indicating if a restroom is for men or women or both; signs advertising what a shop sells; social media stories altering actions that either mitigate climate change or exacerbate it. These all influence physical outcomes through their social significance, based on the fact that we are a symbolic species. 

2. Digital Computers

In all these examples of abstract causation, we can clearly establish its occurrence, but cannot understand in full detail the neural events that lead to its existence. However, there is one case where many levels of abstract causation occur, and we can understand precisely what is going on: namely the way that digital computers function.   

Their functioning is based in two related kinds of abstract entities: algorithms and data. Algorithms are abstract specifications of the logic the machine will carry out. The data is an abstract representation of some physical situation. Returning to the game of chess, when a chess game is played by a digital computer, this adds another level of abstraction to what’s going on: that of the algorithms that play the game, constrained by representation of the rules of chess.

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In his brilliant book Computer Science: A Very Short Introduction, Subrata Dasgupta claims (pp. 22-23) that both physical and abstract causation occurs in digital computers. He states:

As regards digital computers, in its most fundamental, the stuff of computers is systems of symbols, forming symbol structures – that is entities that stand for, denote, or represent other entities. Computing is symbol processing.

He goes on to state:

Some computational artefacts are entirely abstract: they not only process symbol structures, they themselves are symbol structures and are devoid of any physicality, though they may be made visible by physical media such as marks on paper or computer screens. So physico-chemical laws do not apply to them. They neither occupy physical space nor do they consume physical time.

These abstract entities have causal powers via what Dasgupta refers to (p. 23) as Liminal Structures, where the abstract becomes physical and can result in images on a screen, marks on paper, 3D printing of artefacts, automatic landing of an aircraft, etc.

A detailed explanation of how this takes place is given in a paper I wrote with my colleague Barbara Drossel, with the logic embodied in the algorithm chaining down to turn transistors on and off by altering a potential energy term in the quantum equations of motion. This is the detailed physics that enables the Liminal Structures referred to by Dasgupta to change physical outcomes.

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The existence of this downward causation means that physics can't by itself determine the specifics of the computer’s workings.

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Downward causation is the causal influence of entities at higher levels of complexity and abstraction on entities at lower levels. It is taking place logically in the tower of virtual machines, where higher logical levels determine what happens at lower logical levels, and physically in the way that data entered on a keyboard (a macro-level entity) shapes movement of electrons in transistors at the micro level. The existence of this downward causation means that physics can't by itself determine the specifics of the computer’s workings. The physics matters, of course, by underlying how transistors turn on and off according to the gate voltage. But when that happens, and in what order, is dictated by the computer program embodying the underlying algorithms, together with the data the program acts on. These are both provided by the user. And the very existence of the computer and the data is a result of the fact that human minds have agency, including creating and using digital computers.

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3. The Mind Transcends Physics

In the case of the brain, key influences on outcomes are narratives and stories, for example the (untrue) stories about immigrants eating dogs and cats in Ohio that helped shape the outcome of the recent presidential election in the USA. Yuval Harari’s new book Nexus explains in depth the causal power of stories in our historic context. The same is often true also in the case of digital computers, where stories are the drivers of their use in many cases – social media, emails, and news.

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The mind transcends physics by shaping physical outcomes to achieve its goals.

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The confluence of these effects means that physics – the patterns of electrons and protons in the brain, and their interactions – can't by itself determine the mind's workings. Important as it is, physics is just one the mosaic of causal effects that shape brain outcomes. The mind transcends physics by shaping physical outcomes to achieve its goals. It has agency that allows it to do so by downwardly determining the context within which physical forces work. Our understanding of what is happening, whether occurring through the meaning of narratives amplified by associated emotions, or through more formal reasoning, are central to the mind/brain’s functioning and resultant physical outcomes. This is also true of our use of computers and cell phones.

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The reduction of biology and neuroscience to physics is a hopeless project because of their complexity and the contextual nature of how they work.

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None of this is visible at the underlying particle physics level. This reflects the limitations of physics more generally. The reduction of biology and neuroscience to physics is a hopeless project because of their complexity and the contextual nature of how they work. Just one simple example: physics per se cannot explain the occurrence of Darwinian evolutionary processes, because the biological concepts of being alive or dead are not described by any of the variables you will find in physics textbooks. But those concepts are central to the processes determining whether species survive or not.

I strongly recommend to the reader both Eric Kandel’s book on the brain: The Age of Insight: The quest to understand the unconscious in art, mind, and brain, from Vienna 1900 to the present, and Phillip Ball’s book How Life Works as very well-informed introductions to the kind of complexity that occurs in real world biology and neuroscience. There is no possibility whatever that this could be predicted from a deep knowledge of the underlying physics. The project of science as a whole is much more rich than that.