The Role of the Spatial Boundary in Autopoiesis
At the Life & Mind Seminar on Tuesday we very briefly discussed the importance of a spatial (physical) boundary in the context of autopoietic systems. I am interested in this topic, so here is my attempt to rekindle a discussion of it. Here is my view on the importance of a spatial boundary in autopoietic systems.
Much of the conversation on Tuesday focused on the idea of `boundary’ in the context of autopoiesis. There are two boundaries with which we are concerned: the spatial (yesterday often refered to as `the physical’) and the organisational.
A spatial boundary is a delimitation of a contiguous region of space. Examples of spatial boundaries include a soap bubble, a cardboard box and a cell membrane.
An organisational boundary is less easily visualized. It is a delimitation of a set of influential factors. From all of the influential factors involved in a car moving down a road, we can select a certain subset of factors – say those factors that keep the car on the road. However, the organizational boundary from autopoietic theory is a more restrictive concept than just a selection of influential factors. Unlike the selection described above, an autopoietic organizational boundary delimits a contiguous set of enabling processes. If we consider figure 1, this may become clear.
Figure 1: Two types of boundary. End points of arrows represent processes while the arrows themselves represent `enable’.
Let us imagine that this diagram represents all of the processes involved in an abstract system that we are studying. Each processes is represented as a vertex, and each arrow represents the concept of `enables’1. Furthermore, the system includes a physical boundary (described here by a dashed line) that spatially (physically) surrounds certain reactions. Autopoiesis theory suggests that we consider networks of mutually enabling processes. If process P is not enabled by any process P‘ in the network than P is not part of the network. Similarly if there exists no process P‘ within the network that is enabled upon process P then process P can not be part of the network. There is exactly one such network in figure 1; it is the subset enclosed by the organizational boundary (the dotted line). It is easy to deduce that such networks must be reentrant and contiguous. The property of contiguousness allows us to consider the idea of a boundary around such a selection of processes more seriously than we could for a more arbitrary selection of processes (such as the car example above in which the selection of different processes may be non-contiguous and therefore require several distinct boundaries to enclose all of the selected processes).
I believe autopoiesis to be concerned with the organizational boundary as described above, but let us now consider the spatial boundary. A spatial boundary delimits a contiguous region of space. Some autopoietic organizations may produce such spatial boundaries and others may not2. For a variety of reasons (e.g. spatial boundaries are easy to visualize, computational models of autopoiesis tend to include a spatial boundary, the concept of boundary quickly invokes the notion of spatial boundary, etc.), this spatial boundary has been confused with the operational boundary. The spatial boundary has been confused with the boundary fundamental to autopoietic theory. The importance of the spatial boundary has been falsely inflated. I believe that the role of a spatial boundary is simply a spatially-bounding process that enables other processes. For example, by constraining reactants to be in close proximity, the cell membrane enables reactions that would otherwise not be possible. The spatial boundary spatially-encloses certain processes – but this does not give the enclosed processes greater importance or causal value than those processes that occur outside of the spatial-boundary.
In case the above verbal description is not clear, I will try to restate the point diagrammatically. There are two ways to incorporate the concept of the physical boundary into the figure discussed above. The first is to do as I have done in figure 1, to draw a box around certain processes, proclaiming them “inside the physical boundary”. But this is actually incorrect! I have switched the space in which I am diagramming the system. The spatial boundary delineates physical-space, not organizational space. This way of diagramming the spatial boundary is incorrect and may lead to unfortunate lines of inquiry such as “What is special about those mechanisms on the inside of the spatial membrane?”
The more appropriate way to include the spatial boundary in this diagram is depicted in figure 2. Here, the spatial boundary is more accurately represented as a process (vertex) that enables other processes (all of the dashed arrows).
In the past, because it is easily visualizable, because terminology was confusing, because it is common, we have seen the spatial boundary as especially important. But here we see the spatial boundary takes its place among the other enabling processes – not special except perhaps in the great number of processes that it enables.
Does anyone disagree? Does anyone think that the spatial boundary is more important than suggested here?
1For example, say chemical reaction R can only happen within a certain temperature range. If chemical reaction R’ acts as a feedback reaction that maintains total system temperature within the range needed for R to occur, we say R’ enables R.
2On Tuesday, Ezequiel said that he only refers to spatial boundary producing organizations as `autopoietic’ while the more general class of mutually-enabling-networks as described above he considers `autonomous’. Throughout this paper I use the word autopoiesis to refer to this latter, more general class of operationally closed, mutually enabling networks of processes.