This posting is a part of the talk ‘Intelligence and the Brain’. Starting to wrap-up, I will now try to put Karl Friston’s ‘variational Free Energy’ theory of how the brain works into context.
At this point, I am less interested in whether the Free Energy theory is right than whether it could be (approximately) right. Let me explain the difference. And to do that, I want to make a comparison with evolution. I am presenting the Free Energy theory as a theory (albeit a rather speculative theory) that explains intelligence in terms of physical mechanisms. This is in a similar way to how Darwinian evolution explains life in terms of physical mechanisms.
For an explanation of life in physical terms:
- The general theory was provided by Darwin in 1859.
- The underlying theoretical fundamentals were provided by Schrödinger in 1944.
- The actual physical mechanism was provided by Watson & Crick in 1953.
It took time – the best part of 100 years – to get from an initial correct theory to a satisfactory physical explanation.
Friston’s theory provides all 3 corresponding aspects for a theory of intelligence:
- the general theory is that of ‘minimization of surprise through action and perception’.
- the fundamentals are of Bayesian minimization of entropy.
- the actual physical mechanism is suggested to be within neural cortical columns (with much more work needed on this).
But if I were to suggest a historical date for comparison with evolution, I would suggest that Free Energy is currently where evolution was in around the year 1800 – around the time of Lamarckian evolution. Recall: Lamarck provided a theory of evolution whereby offspring inherited characteristics acquired by their parents during their parents’ lifespan, for example, a giraffe stretching its neck to reach the highest branches of trees will have offspring with longer necks than it if had not stretched. The point here: Lamarckism may be a wrong theory but it provided an example of what a correct theory might look like, 150 years before all the science was put in place. On a scale from ‘creationism’ to ‘DNA’, Lamarckism is right next to ‘DNA’ – it is right on the big issues and wrong on the details. Now, it may be 150 years before we have a comparable scientific theory for intelligence. None of us alive today will be around then. Here, I want to provide a glimpse at what that (correct) theory of intelligence might look like.
At this point, the Free Energy theory provides some understanding of how we can relate the behaviour of a whole organism (a whole brain organ), comprising many billions of neurons, to the behaviour of relatively few neurons. In providing this as an example, we are suggesting what is not there:
- There’s no ‘magic’ deviation from the laws of physics – even as currently understood.
- There’s no reliance on complications such as indeterminacy, quantum phenomena and randomness that many want to include.
Whether the theory has any merit will be tested over the coming years – decades, even. How far up the scale will the theory take us? Maybe it will have some explanatory value all the way to the ‘top layers’ and, in doing so, allow us to explain the behaviour of whole organisms. But I guess it will need one or more extra ideas to get us there. There’s a big gap to bridge: there are many orders of magnitude from a single neuron in a hypercolumn to the 10-billion-ish neurons in a cerebral hemisphere.