Hierarchy Part 2: Herbert A. Simon and “Near-decomposability”

neardecomposability

“Why is reality structured at all?” was what Herbert Simon, an extraordinary polymath regarded as one of last century’s most influential thinkers, asked himself in his watchmaker parable from the article “The Architecture of Complexity” (1962).

Imagine two watchmakers constructing equally complex watches that each consist of 1000 elementary units. One watchmaker constructs his so that if he had assembled some parts and then was disturbed the watch would fall into pieces and would have to be reassembled from scratch. As a result, he quickly runs out of business.  The other watchmaker organizes his watch into stable subassemblies of ten parts each, to make up a super-assembly of ten, and so on. If he is disturbed, the watch would fall back on the last intermediate subassembly level. His work loss is therefore smaller by orders of magnitude. Needless to say, he prospered.

The gist is that systems analyzable into successive sets of subsystems evolve more rapidly than non-hierarchic systems, because the time it takes to achieve complexity depends on the number of potential intermediates. In the survival of the stable, only hierarchies have time to evolve. Simon calls this feature of reality “near-decomposability” and examples, I am sure, come readily to mind.

Atoms are decomposable into protons, neutrons, electrons and a collection of more exotic particles.

Organisms are decomposable into organ systems, organs, tissues, cells and organelles.

Societies are decomposable into countries, counties, cities, and families.

Language is decomposable into phrases, words, morphemes and phonemes.

But there are also more subtle instances of hierarchy.

The successful portraiture drawing starts with a shadowy “gestalt”, an angular block-in, with gradually more landmarks specified.

Literature involves conveying emotion by carefully crafting the psychological dynamics interactively at plot, paragraph, sentence, and word level.

Altruism proceeds from the level of the ecosystem, to populations, kin, and down to individuals. Treating a friend well is irrational if it hurts society as a whole.

Consider any physical system of choice – any dynamic with some kind of integrity, be it an atom, an organism, a society, or a process such as origami-folding. There is no requirement for it to be visibly perceivable as long as it is derived from experience, because if it is viable as a category in your mind, then clearly it has integrity enough to be reasoned about. This system is constantly at risk of losing its identity in response to disruptive events in the environment: an atom my find itself forced to fission in a nuclear reactor, an organism may die from a pathogen targeting some homeostatic mechanism, a society may disintegrate from barbarian ravaging, and origami-folding may be disturbed by shaky hands.

The integrity that distinguished it from the environment in the first place derives from how elements within it interact more intensely with each other than with elements of the outside. For example, family members interact more intensely with each other than neighbors do.  Inter-molecules forces are weaker than intra-molecular bonds. Glass, like water, is a liquid but its flow rate is much slower, so the relative reaction rates define the system boundaries of the water inside it. As a consequence, events at different levels have different characteristic time frequencies. Whatever your system is, the subsystem can be treated as an aggregate, because events there occur too quickly for differentiation, and likewise the super-component, because of its relative slowness, can be regarded as a context.

This system can be considered a subunit of a potential, higher level of organization. However, for this to occur, a system must maintain integrity while modifying itself so that the disturbance ceases to be disruptive and instead is incorporated as a functional component. After a forest has been disturbed by a fire, natural selection will ensure that next time it strikes the fire will encounter more hardy plants. The fire can now be considered a working component of the eco-system, in the absence of which hardy plants will no longer be at an advantage. Similarly, the nervous system is structurally modified from interaction with the environment in the process we call “learning”. In information-theoretic terms, what happens is that you encode information from the environment so that you can choose adaptive responses to meet your goals and persist as a human being, even though the matter and energy that constitute you are constantly replaced and dissipated.

The ability to retain integrity in the face of disturbance is referred to as “reproduction” – imperfect self-replication – and it is what characterizes lineages undergoing natural selection, organisms undergoing learning, as well as other processes outside of the biological domain that we would identify as “complex”. To understand how reproduction is fundamentally hierarchical, we shall refer to a different author.

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About lovisasundin

I study psychology and computing science in Glasgow but am originally from Sweden. I like drawing and popular science. Please don't hesitate to contact me at lovisafsundin@gmail.com
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