A hierarchy is a pattern of order along which objects may be ranked from a maximum to a minimum value along some dimension. The word is derived from the Greek words -hiero', meaning sacred/ and 'archon', meaning ruler. The pattern is often pictured as a pyramid or a vertical tree. It may be described in words or in the rigor of mathematics. Hierarchies are **ubiquitous in nature, in human affairs and even in the abstract realm of ideas**. This can be confusing; although they all share the **unidirectional ranking** they may differ in many other characteristics.
In some contexts, such as the Roman Catholic church, or the organization chart of a bureaucracy, hierarchy retains an association with authority. The source of these hierarchies is direct human action, whether it stems from divine messages, from the electorate or arbitrary factors. There are other contexts which are not associated with authority, although the source of the identified hierarchies still lies in their selection by human observers. Biology, chemistry and physics belong to this class. Finally, there are contexts where the distinction based on the influence of authority is not so clear. They include human organizations of all types from families, which have their counterparts in animal society, to complex manufacturing and financial organizations. This is the area of social investigation and innovation - and ultimately of political decision.
One of the most familiar forms of hierarchy is **classification**. In the process laid down by Aristotle, those criteria which yielded increasingly specific classes were chosen in preference to features like color and weight which did not. His scheme allowed for a relatively few decision rules to lead quickly to thousands of distinct species, each having many characteristics in common with others in the same genus, family and so on.
Hierarchical ordering in nature and in human affairs is a means of **managing and facilitating complexity**. Sometimes constraint and control emerge at threshold levels such as seen when the concentration of one celled animals suddenly begins to differentiate and a colony is formed or when human settlements reach a certain density and traffic and zoning by-laws are introduced. Pattee has noted that one of the paradoxes of hierarchy is that it **both constrains and enhances freedom**: e.g. the constraints of the genetic code on chemistry make the diversity of living forms possible while the rules of spelling and syntax permit the free expression of ideas. It has also been noted that hierarchical arrangements **allow for experiments** to be tried. In evolution, in a **subroutine** for a computer program or in a stage in a manufacturing operation, a change can be incorporated into the whole if it works or the damage contained if it doesn't.
Another factor which distinguishes hierarchies is the extent to which lower levels are recursively contained in upper levels. Allen and Starr point out that while nested hierarchies are very useful in modeling situations, it is **not necessarily possible to use the same criteria for more than two levels in a row**. In contrast, in non-nested hierarchies, the chosen criterion remains constant and comparisons may be made across many situations.
A heterarchy is an alternative to hierarchy. It may make decisions democratically or the idea of primacy may be retained but the identity of the leader or the preferred alternative will vary. Heterarchies tend to be pictured by rings or nets. The **leadership may shift** on the basis of who has the best information or the most expertise, according to rotation or according to logistical considerations. Warren McCulloch showed in 'A Heterarchy of Values Determined by the Topology of Nervous Nets' that with as few as three alternatives, (e.g. A is preferred to B, B is preferred to C and C is preferred to A) the establishment of a summum bonum could be impossible.
# SOURCE Pattee, H. (Ed.). (1973). Hierarchy Theory: the ChallengeofComplex Systems. New York: Braziller. Wyte, L. L., Wilson, A., & Wilson, D. (Eds.). (1969) Hierarchical Structures. New York: Elsevier. Mesarovic, N. D., Macko, D., & Takahara, Y, (1970) . Theory ofHierarchical Multilevel Systems. New York: Academic Press. Allen, T. F. H., & Starr, B. (1982). Hierarchy. Chicago: University of Chicago Press. # EXAMPLES • the pecking order of chickens • the food chain • in computers; from higher level to * lower level languages to machine language to the physical properties of the computer or the reverse • in natural language, phonemes, morphemes, words, phrases, sentences, paragraphs... • in physics, forces binding atoms, molecules, macromolecules... # NON-EXAMPLES • a pile of stones • an alphabetical ranking of names • a succession of waves along a beach # PROBABLE ERROR • following the identification of a hierarchy with unsupportable assumptions about consistency in criteria, the place of information selection or the role of authority. • failing to take advantage of the full rigor possible in analyzing some hierarchical situations. # SEE • Self-Organization: Closure; Recursion
The Viable System Model consisted of five tiers that Beer based on the human nervous system.