Mathematician George Ellis made his name focusing on some of the big questions of cosmology and relativity. Along with Stephen Hawking, he co-authored 1973’s The Large Scale Structure of Space-Time, which attempted to describe the very foundations of space itself.

More recently, Ellis has been focusing on top-down causation – the process by which higher level organised systems, such as humans, interact with their own component parts. His theories have important repercussions across many fields of research – from consciousness and free will to understanding quantum phenomena. Ellis is also an active Quaker and was a vocal opponent of apartheid during the 1970s and ‘80s.

We spoke to Ellis about his theories, their implications, and the reasons behind certain resistance to these ideas.

What exactly is top-down causation?

A key question for science is whether all causation is from the bottom up only. If forces between particles are the only kind of physical causation, then chemistry, biology, and even our minds are emergent, bottom-up properties of physics. On the other hand, it might be that these emergent higher level structures, such as cells, neurons, and the brain, have causal powers in their one right.

In the first instance, all the higher levels are epiphenomena – they have no real existence – and so the idea that you are responsible for your actions is false. But in fact top-down causation takes place all the time, with the higher levels controlling the lower levels, not by any magic force, but by setting constraints on lower level interactions. This means that higher levels such as cells, neurons, and your brain have real causal powers, and this means you can indeed be held accountable for your actions.

The scale of modern physics ranges from superstrings to the edges of the observable universe and beyond; is top-down causation present across all orders of magnitude, or is it confined to macroscopic phenomena?

It happens across all scales; indeed it is the key to many quantum phenomena. Superconductivity is a great example, as is state vector preparation in quantum physics. I have written about this in more detail for the Annals of Physics.

Does top-down causation only allow us to explain observed phenomena, or can it enable us to make new predictions?

It enables higher level effective causation to be real. Cellular biology is real, neuroscience is real, evolutionary theory is real, and so on. In each case, one understands how higher level effects (like spikes in neurons) arise through lower level physics (flow of ions through gated channels) as directed by the higher level context. So your nerve cells act together to produce spoken English as a result both of your social context and education, and also your immediate train of thought. Top-down causation explains the interactions between the levels, and this is what governs what actually happens.

What does top-down causation add to metaphysical problems such as free will and consciousness?

It is a major component in resolving those issues. It frees us from the illusion that physics by itself controls everything. Context matters all the time.

Could top-down causation explain why the universe appears to be fine-tuned for supporting life?

Ah that is much more controversial. It is possible, but that is a metaphysical rather than scientific claim. My arguments above are all about science rather than metaphysics.

The study of complex systems is an emerging field in both the social and physical sciences, yet many in research still hold a reductionist point of view. Could you explain the reluctance of some to abandon the more traditional way of thinking about cause and effect?

Reductionism does indeed have enormous causal power, and so is a key part of what happens, but it is only part of the story. Reluctance to accept top-down causation has two roots. One is an intellectual concern about how this is possible in scientific terns – how can it be understood in the face of the apparent iron grip of physical causation at the lower levels? That is what I am writing about in various books and articles, such as my fqxi essay.

The second is a tendency of many academics towards fundamentalism, that is, to claim that the partial truth that they happen to be experts in (which is indeed true) is the only truth – it is the only game in town, and nothing else matters. The reasons for this are, I suppose, emotional and psychological, but it leads to its proponents disregarding inconvenient evidence that contradicts their views. A great example is the debate on genetics, evolution, and development, where proponents of the gene-centered view deny contrary evidence from physiology, developmental biology, epigenetics, and evolutionary history. I've written about this kind of fundamentalism here. 

You describe yourself as a moral-realist. Has your career in science influenced your moral stance?

No. My experience as a social activist underlies my views on those topics. Science per se has nothing to say on this issue.

Where do your allegiances lie with the ongoing quest for a universal theory of everything?

It seems to me – as an outside spectator – that the drive to propose superstring/M theory as a theory of everything is losing steam. Certainly supersymmetry is not supported by the latest experimental evidence, even though it may have strong theoretical arguments in its favour. In any case I hope for a four-dimensional theory rather than one of the many higher dimensional theories. I remain a spectator watching with interest!