Edge

The edge of a system is the boundary where it interacts with its neighbours and environment. This is where it protects, cooperates, competes; where it exports waste and imports nutrients; it is where systems meet. And there are three principles to note:

1. Diversity and productivity. At the join between two systems, there is mixing and interaction which can make the edge more complex and more productive than either of the systems on their own. This effect, as Patrick Whitefield explains, is used in permaculture, with its intimate mixture of woods and fields, its layered crops of diverse varieties and heights, and the use of ponds, river margins and shallow water. River estuaries, where fresh water and sea mix, and which receive a supply of nutrients from the land and daily refreshment with oxygen from the tides, are exceptionally fertile: some estuaries are as productive as a tropical rainforest.^E87

2. A high edge ratio. Edge ratio is the ratio of a system’s edge relative to its area (or, for a system considered in three dimensions, its surface area relative to its volume). As discussed in the entry on scale, if we compare figures of the same shape but different sizes, the smaller a system’s size, the greater its edge ratio. Small systems, having a relatively high edge ratio, can import nutrients and exchange wastes across short distances. Large systems that are well subdivided into smaller holons with a substantial hinterland—space for their primary needs: energy, food, water and materials, for reciprocal exchange with other systems, and for waste disposal—may develop a high degree of efficiency and self-reliance.

3. The Edge of Chaos. The idea suggested by the computer scientist Christopher Langton in 1990 about the point of intersection between two states: solid and fluid. In the solid phase, there is no movement; in the liquid phase, there is no stillness; at the borderline between them, there is the possibility of structures developing and then holding their new shapes—or holding new information, like a semiconductor. The extent to which this should be taken as a metaphor, and what kinds of system it should be applied to, is debated, but the principle applies in many situations, such as teaching (the case for moderate discipline) and lean thinking, where the common purpose defines a frame of reference for individual decision-making.^E88

The edge of a system is the place to observe closely for signs of change which is likely—for better or for worse—to affect the system as a whole. At the “active fringe”, interesting things happen, as explained by the systems analyst Alex Trisoglio:

Most organisations and entities have a core, where most of their activity is focused, so diversity must be expressed largely at the fringes. The fringes are the source of most truly innovatory ideas in cultures, economies and organisations.^E89

Totnes (the first Transition Town) is inventive because it is on the fringe, neither a village nor a substantial town. Small companies are diverse and inventive. Small schools would be too, if they were allowed to be. If you are in the mainstream, it is harder: you are swept along.

Surprising happenings at the fringe may be a warning that the system will in due course need to transform itself if it is to survive. A radical vision will tend to be resisted, but the system’s resilience depends on whether it is able make sense of such visions, rather than dismissing them as harmless lunacy.