Saturday, May 27, 2017

Complex Systems (more than the sum of their parts)

I have a real love-hate relationship with the academic study of complexity. On the one hand, some topics that are of interest to this blog are complex-chaotic systems: the economy, weather, markets etc. but on the other hand the application of the terminology of complexity to broad swaths of human stuff seems a bit too facile.
Which is the right approach? Who knows.
I do know people are "explaining" animals and sometimes our explanations end up corresponding in some degree with what is going on.

From Aeon:

The mathematics of mind-time
The special trick of consciousness is being able to project action and time into a range of possible futures
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? For example, Isaac Newton explained the physical world in terms of massive bodies that respond to forces. However, with the advent of quantum physics, the real question turned out to be the very nature and meaning of the measurements upon which the notions of mass and force depend – a question that’s still debated today.

As a consequence, I’m compelled to treat consciousness as a process to be understood, not as a thing to be defined. Simply put, my argument is that consciousness is nothing more and nothing less than a natural process such as evolution or the weather. My favourite trick to illustrate the notion of consciousness as a process is to replace the word ‘consciousness’ with ‘evolution’ – and see if the question still makes sense. For example, the question What is consciousness for? becomes What is evolution for? Scientifically speaking, of course, we know that evolution is not for anything. It doesn’t perform a function or have reasons for doing what it does – it’s an unfolding process that can be understood only on its own terms. Since we are all the product of evolution, the same would seem to hold for consciousness and the self.

My view on consciousness resonates with that of the philosopher Daniel Dennett, who has spent his career trying to understand the origin of the mind. Dennett is concerned with how mindless, mere ‘causes’ (A leads to B) can give rise to the species of mindful ‘reasons’ as we know them (A happens so that B can happen). Dennett’s solution is what he calls ‘Darwin’s dangerous idea’: the insight that it’s possible to have design in the absence of a designer, competence in the absence of comprehension, and reasons (or ‘free-floating rationales’) in the absence of reasoners. A population of beetles that has outstripped another has probably done so for some ‘reason’ we can identify – a favourable mutation which produces a more camouflaging colour, for example. ‘Natural selection is thus an automatic reason-finder, which “discovers” and “endorses” and “focuses” reasons over many generations,’ Dennett writes in From Bacteria to Bach and Back: The Evolution of Minds (2017). ‘The scare quotes are to remind us that natural selection doesn’t have a mind, doesn’t itself have reasons, but is nevertheless competent to perform this “task” of design refinement.’

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. We are thrown into the world as a process already in motion; and processes can only reason towards what is ‘out there’ based on sparse (if carefully selected) samples of the world. This view dissolves familiar dialectics between mind and matter, self and world, and representationalism (we depict reality as it is) and emergentism (reality comes into being through our abductive encounters with the world). But just how did inference happen before there were inferrers around to do it? How did inert matter ever begin the processes that led to consciousness?

Let’s first establish a few ground rules about the nature of processes, and see how far we get. We’re interested only in the processes that make up complex systems, those objects of study that are more than the sum of their parts. A good way to understand this notion is to look at its opposite. If you fire a gun at a target, it’s easy enough for a physicist to anticipate which part of the bullseye it will hit, based on the angle and momentum of the bullet as it leaves the barrel. That’s because the firing range is nearly a linear system, whose overall behaviour is determined by the interaction of its constituent bits, in a one-way fashion. But you can’t pinpoint the precise position of an electron when it’s circling an atom, or say for sure if and when a hurricane will hit New York next year. That’s because the weather and atoms – like all natural processes – are not reliably determined by their initial conditions, but by the system’s own behaviour as it feeds back into the interactions of its component parts. In other words, they are complex systems.

According to physicists, complex systems can be characterised by their states, captured by variables with a range of possible values. In quantum systems, for example, the state of a particle can be described by a wave function that entails its position, momentum, energy and spin. For larger systems, such as ourselves, our state encompasses all the positions and motions of our bodily parts, the electrochemical states of the brain, the physiological changes in the organs, and so on. Formally speaking, the state of a system corresponds to its coordinates in the space of possible states, with different axes for different variables.
Everything should actually get more random, dispersed and chaotic as time marches on. So what’s going on?
The way something moves through this space depends on its Lyapunov function. This is a mathematical quantity that describes how a system is likely to behave under specific conditions. It returns the probability of being in any particular state as a function of that state (or, put differently, as a function of the system’s position in the state space, similar to how air pressure is a function of the density of air molecules at the point at which it’s measured). If we know the Lyapunov function for each state of the system, we can write down its flow from one state to the next – and so characterise the existence of the whole system in terms of that flow. It’s like knowing the height of a mountainous landscape at every location, and then being able to describe how a stream of water will run over its surface. The topography of the mountain stands for the Lyapunov function, and the movement of water describes how the system evolves over time....MORE