Becoming Water

Bruce Lee was not a great philosopher. But he did beat Chuck Norris, so there’s that. His words here are not terrifically original, but they stem from an orthodox understanding of the nature of skilled human action as expressed within the Daoist tradition.

“Empty your mind, be formless, shapeless – like water. Now you put water into a cup, it becomes the cup, you put water into a bottle, it becomes the bottle, you put it in a teapot, it becomes the teapot. Now water can flow or it can crash. Be water, my friend.” — Bruce Lee.

Daoism is concerned with non-volitional action (wu wei), that is with understanding the manifestation of action as if there were no psychologically endowed agent involved, who heroically overcomes the limits of the world to place his stamp upon it.  The psychological tradition would have it that we are responsible for our actions (a Protestant fantasy), and our brains are the puppeteer, willing the body to go hither and thither (again, the Christian view).  

An analysis of skilled action does not support the notion that the brain and body constitute an agent who controls action.  Firstly, the most important discovery of the 20th century in movement science is the recognition that in skilled action, the body fluidly adopts a configuration that constitutes a mechanism for performing the task.  This on-the-fly assembly of very very many degrees of freedom into a constrained unity that acts as a whole towards the accomplishment of a goal goes by the name of a Coordinative Structure or a Synergy.  The original insight is from Bernstein, but useful book-level sources include Kelso’s “Dynamic Patterns“, and Latash’s “Synergy“.

The components that come together are not necessarily cut from the same cloth.  I said “the body adopts a configuration”, but the components may be parts of the body (as in speaking), the whole body (e.g. in running), the body plus tools and other environmental elements, multiple bodies, etc. There is no a priori preferred set of components. In order to come together in this fashion, the components need to be coupled, and possessed of very many degrees of freedom.  The resulting configuration speaks of a goal.  (Who owns the goal?  Who asks the question?)

This perspective on movement recognises the role of skill.  Unskilled movement is clunkily strung together out of individual parts that do not cohere.  I am reminded of my incompetence on the piano as I try to pick out a fast be-bop tune, and it turns instead into a disastrous sequence of unallied parts with hesitations, false-starts, corrections, and curses.  We recognise skill, of course, only when we have our normative glasses on that distinguish good from bad performance.  There is no such thing as a “bad” avalanche, in this sense, but there is “good” piano playing. When skilfully done, the resulting performance exhibits movement in a highly constrained space, and the many redundant degrees of freedom are invisible.

This view of skilled movement tends to be congenial to scientists within the traditions of ecological psychology and enaction (on their relation, see this post).  The consequences have not been drawn in full by either school.

Which brings me to this excellent 2010 paper by Stepp and Turvey: On Strong Anticipation.  They take on the increasingly popular world of “predictive models”, which try to understand the success of individual bodies in dealing with a somewhat unpredictable world, by leaning on the notion of internal simulation, or prediction.  There are very many such accounts, and they are something of a flavour of the month, not least due to the increasing awareness of the strength of a Bayesian framework.  Stepp and Turvey criticise the representational view, in which “I”, considered as a brain (perhaps with body), choose to act upon the world, and to do so, I need to model the world, so that I can tell if things are going to plan.  This is, of course, the agent-based view I took issue with above. When I move, I (or rather some suite of computational processes in my brain) direct my body to move, but I must also predict the sensory consequences of such movement, and compare those with the actual sensory consequences, in order to adjust as needed.  This seems computationally bizarre and prima facie unlikely (and ugly?), but I routinely see computers do things in 2015 that I would have considered impossible in 1990, so mere computational implausibility is not a strong counter argument.

However, Stepp and Turvey offer a highly intriguing alternative that seems to me to be much better aligned with the nature of skilled action, as expressed in a synergy.  They illustrate how two dynamical systems can be coupled together such that one system then anticipates the other, without it having to model or represent the other in any way.  More specifically, they discuss unidirectional coupling, so one system acts as Master and the other as Slave (don’t you love science?), and the slave anticipates future behaviour of the master.  Think of your relationship to the cycle of day and night.  The sun affects you greatly, but you don’t really influence the sun so much, so for all practical purposes, that is unidirectional coupling.

Using a range of relatively simple mathematical examples, they demonstrate that such anticipatory coupling readily arises, under specific conditions, without either system having to represent the other.  What is needed is a specific form of coupling, in which the coupling term depends, not on the present state of the slave, but on the time-delayed state, at some point t-τ in the past.  This kind of coupling brings the present state of the master into alignment with a past state of the slave, or the present state of the slave into alignment with a future state of the master.  The time delay in the coupling term is key here, but otherwise the phenomenon is quite generic and is illustrated with several different kinds of system.  Perhaps the easiest to follow mathematically is coupling among two Rössler oscillators: a minimalist dynamical system that exhibits a very clear kind of chaotic behaviour with a beautiful attractor structure.

The quite profound shift that is thereby effected comes when you realise just what the mathematics has made perfectly explicit. Anticipatory coupling arises when the dynamics of the two systems become intertwined, such that we are no longer looking at two distinct systems, but at one super-ordinate system, in which a strict separation of one system from the other is no longer possible.  We are then faced, not with “how does the outfielder catch the ball?”  but with “what are the dynamics of the coupled fielder-ball system?”.

Describing the two coupled systems licences once more the use of the term “information”, which now can be rigorously defined relative to the system so identified. This is, of course, a very fundamental insight we owe to the ecological tradition.

But I will wrap up by coming back to Bruce Lee and being water.  On this view, there is no clear separation between subjects and their worlds. The subject lies at the dimensionless centre of a constant stream of activity in which the essentially infinite degrees of freedom acquire determinate form by flowing into the structure of a “locomotion machine”, a “writing machine”, or, in a predictive context, a “ball and fielder” machine.  The challenge raised for us by the notion of coordinative structure or synergy gets even more interesting as the dynamical tools allow us to better describe with some precision how we are enmeshed in webs of purpose, without any identifiable discrete agents.

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