There is a popular view that all of the natural sciences can be arranged in a chain or ladder according to the complexity of their subjects.

On this view, physics forms the base of the ladder because it deals with the simplest building-blocks of matter, atoms and subatomic particles. Chemistry is next up because it studies interacting atoms i.e. molecules. Biology studies complex collections of molecules, i.e. cells. Then comes neuroscience which deals with a complex collection of interacting cells – the brain. Psychology, perhaps, can be seen as the next level above neuroscience, because psychology studies brains interacting with each other and with the environment.

So this on this model, we have a kind of Great Chain of Science, something like this:

This is an appealing model. But is biology really basic to neuroscience (and psychology)?

At first glance it seems like biology – most importantly cell and molecular biology – surely is basic to neuroscience. After all, brains are comprised of cells. All of the functions of brain cells, like synaptic transmission and plasticity, are products of biological machinery, i.e. proteins and ultimately genes. This doesn’t imply that neuroscience could be ‘reduced to’ biology, any more than biology will ever be reduced to pure chemistry, but it does seem to imply that biology is the foundation for neuroscience.

However, could this be a mistake?

Consider computers as an analogy. Suppose that everyone in the world suddenly forgot how computers work. Scientists would start to study them, creating a discipline of ‘computoscience’. Now, eventually scientists would discover that all computers are based around electronic circuits built out of semiconductors. They would discover that physics can explain how electrons flow through circuits. Scientists might therefore conclude that computoscience is based on physics.

This would be a mistake, however. In fact, while computers are indeed electronic devices, this is only an accident. In theory, a computer could be built of almost anything. The essence of a computer is not electronics but computation: the storage and manipulation of symbols. The foundation of computer science is logic, a branch of mathematics, not physics, even though the physics of electricity can be used to implement that logic.

Could it be that brains are only accidentally made of cells, just as computers are only accidentally made of semiconductors? If so, neuroscience would not be founded on biology but on something else, something analogous to the mathematical logic that underpins computer science. What could this be?

It’s possible that brains are computers and that neuroscience will one day be unified with computer science. In that case, the same logic would underlie both. But that’s not the only possibility. The underlying principle of neuroscience may be something else, something that remains to be discovered. This would be an abstract system that happens to be implemented through biology in the form of brains.

If that’s the case, a large proportion of today’s neuroscience, being focused on biology (synapses, receptors, blood flow, etc.) is contributing to our understanding of neuro-biology, but it’s not helping us to understand the brain per se, any more than electrical research could help us understand computer programming. I’m not sure I believe that, but it’s a worrying thought.