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Tuesday, June 27, 2017

It is abduction all the way down

But fortunately not that kind of abduction. 

A few weeks ago Aeon published a fascinating article by Karl Friston, but first of all it may be worthwhile to see what Wikipedia says about the man who wrote it.

Karl Friston pioneered and developed the single most powerful technique for analysing the results of brain imaging studies and unravelling the patterns of cortical activity and the relationship of different cortical areas to one another. Currently over 90% of papers published in brain imaging use his method (SPM or Statistical Parametric Mapping) and this approach is now finding more diverse applications, for example, in the analysis of EEG and MEG data. His method has revolutionized studies of the human brain and given us profound insights into its operations. None has had as major an influence as Friston on the development of human brain studies in the past twenty-five years.

In which case we may take it that Friston is no professional waffler. However, it is not easy to summarise his article because there are a number of interwoven strands, but his starting point is to focus on processes rather than things.

I have a confession. As a physicist and psychiatrist, I find it difficult to engage with conversations about consciousness. My biggest gripe is that the philosophers and cognitive scientists who tend to pose the questions often assume that the mind is a thing, whose existence can be identified by the attributes it has or the purposes it fulfils.

But in physics, it’s dangerous to assume that things ‘exist’ in any conventional sense. Instead, the deeper question is: what sorts of processes give rise to the notion (or illusion) that something exists?

To accept consciousness as a process rather than a thing is not at all difficult and many people may do that anyway, but from this simple adjustment to our thinking some remarkable conclusions follow.   

I hope to show you that nature can drum up reasons without actually having them for herself. In what follows, I’m going to argue that things don’t exist for reasons, but certain processes can nonetheless be cast as engaged in reasoning. I use ‘reasoning’ here to mean explanations that arise from inference or abduction – that is, trying to account for observations in terms of latent causes, rules or principles.

This perspective on process leads us to an elegant, if rather deflationary, story about why the mind exists. Inference is actually quite close to a theory of everything – including evolution, consciousness, and life itself. It is abduction all the way down.

Friston then moves on to the oddity of life as repetitive, self-organising behaviour which as he says, seems contrary to how the universe usually behaves.

Complex systems are self-organising because they possess attractors. These are cycles of mutually reinforcing states that allow processes to achieve a point of stability, not by losing energy until they stop, but through what’s known as dynamic equilibrium. An intuitive example is homeostasis. If you’re startled by a predator, your heartbeat and breathing will speed up, but you’ll automatically do something to restore your cardiovascular system to a calmer state (following the so-called ‘fight or flight’ response). Any time there’s a deviation from the attractor, this triggers flows of thoughts, feelings and movements that eventually take you back to your cycle of attracting, familiar states. In humans, all the excitations of our body and brain can be described as moving towards our attractors, that is, towards our most probable states.

A little further on we get to a crucial point in the whole piece.
It’s at this point that we can talk about inference, the process of figuring out the best principle or hypothesis that explains the observed states of that system we call ‘the world’. Technically, inference entails maximising the evidence for a model of the world. Because we are obliged to maximise evidence, we are – effectively – making inferences about the world using ourselves as a model. That’s why every time you have a new experience, you engage in some kind of inference to try to fit what’s happening into a familiar pattern, or to revise your internal states so as to take account of this new fact. This is just the kind of process a statistician goes through in trying to decide whether she needs new rules to account for the spread of a disease, or whether the collapse of a bank ought to affect the way she models the economy.

Now we can see why attractors are so crucial. An attracting state has a low surprise and high evidence. Complex systems therefore fall into familiar, reliable cycles because these processes are necessarily engaged in validating the principle that underpins their own existence. Attractors push systems to fall into predictable states and thereby reinforce the model that the system has generated of its world. A failure of this surprise minimising, self-evidencing, inferential behaviour means the system will decay into surprising, unfamiliar states – until it no longer exists in any meaningful way. Attractors are the product of processes engaging in inference to summon themselves into being. In other words, attractors are the foundation of what it means to be alive.
As suggested above, there is little point in trying to summarise Friston's article, not because it is too difficult but because all the steps are worth following. However, one more quote may give a flavour of the whole piece.
Applying the same thinking to consciousness suggests that consciousness must also be a process of inference. Conscious processing is about inferring the causes of sensory states, and thereby navigating the world to elude surprises. While natural selection performs inference by selecting among different creatures, consciousness performs inference by selecting among different states of the same creature (in particular, its brain). There is a vast amount of anatomical and physiological evidence in support of this notion. If one regards the brain as a self-evidencing organ of inference, almost every one of its anatomical and physiological aspects seems geared to minimise surprise.

So consciousness is a process of navigating the world to elude surprises. That at least is no surprise, as indeed it shouldn't be if Friston is right.

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