:''For the various types of hierarchy, see
hierarchy (disambiguation)''
A 'hierarchy' (in
Greek: '', derived from '' — ''hieros'', 'sacred', and '' — ''arkho'', 'rule') is a system of
ranking and organizing things or people, where each element of the system (except for the top element) is subordinate to a single other element.
The first use of the word "hierarchy" cited by the
Oxford English Dictionary was in
1880, when it was used in reference to the three orders of three angels as depicted by
Pseudo-Dionysius the Areopagite. Pseudo-Dionysius used the word both in reference to the celestial hierarchy and the ecclesiastical hierarchy
[1]. His term is derived from the Greek for 'Bishop' (hierarch), and Dionysius is credited with first use of it as an abstract noun. Since hierarchical
churches, such as the
Roman Catholic and
Eastern Orthodox churches, had tables of organization that were "hierarchical" in the modern sense of the word (traditionally with
God as the pinnacle of the hierarchy), the term came to refer to similar organizational methods in more general settings.
A hierarchy can link entities either directly or indirectly, and either vertically or horizontally. The only direct links in a hierarchy, insofar as they are hierarchical, are to one's immediate superior or to one of one's subordinates, although a system that is largely hierarchical can also incorporate other organizational patterns. Indirect hierarchical links can extend "vertically" upwards or downwards via multiple links in the same direction. All parts of the hierarchy which are not vertically linked to one another can nevertheless be "horizontally" linked by traveling up the hierarchy to find a common direct or indirect superior, and then down again. This is akin to two co-workers, neither of whom is the other's boss, but both of whose chains of command will eventually meet.
These relationships can be formalized mathematically; see
hierarchy (mathematics).
Computation and electronics
Large
electronic devices such as
computers are usually composed of modules, which are themselves created out of smaller components (
integrated circuits), which in turn are internally organized using hierarchical methods (e.g. using standard cells). The order of tasks in a computational
algorithm is often managed hierarchically, with repeated loops nested within one another.
Computer files in a
file system are stored in a hierarchy of
directories in most
operating systems. In
object-oriented programming, classes are organized hierarchically; the relationship between two related classes is called
inheritance. In the
Internet,
IP addresses are increasingly organized in a
hierarchy (so that the
routing will continue to function as the Internet grows).
Computer Graphic Imaging (CGI)
Within most
CGI and
computer animation programs is the use of hierarchies. On a
3D model of a
human, the
chest is a
parent of the upper left arm, which is a
parent of the lower left arm, which is a
parent of the
hand. This is used in
modeling and
animation of almost everything built as a 3D
digital model.
Biological taxonomy
In
biology, the study of
taxonomy is one of the most conventionally hierarchical kinds of knowledge, placing all living beings in a nested structure of divisions related to their probable evolutionary descent. Most evolutionary biologists assert a hierarchy extending from the level of the specimen (an individual living organism — say, a single newt), to the species of which it is a member (perhaps the
Eastern Newt), outward to further successive levels of
genus, family, order, class, phylum, and kingdom. (A newt is a kind of salamander (family), and all salamanders are types of amphibians (class), which are all types of vertebrates (phylum).) Essential to this kind of reasoning is the proof that members of a division on one level are more closely related to one another than to members of a different division on the same level; they must also share ancestry in the level above. Thus, the system is hierarchical because it forbids the possibility of overlapping categories. For example, it will not permit a 'family' of beings containing some examples that are amphibians and others that are reptiles — divisions on any level do not straddle the categories of structure that are hierarchically above it. (Such straddling would be an example of
heterarchy.)
Organisms are also commonly described as assemblies of parts (organs) which are themselves assemblies of yet smaller parts. When we observe that the relationship of cell to organ is like that of the relationship of organ to body, we are invoking the hierarchical aspects of physiology. (The term "organic" is often used to describe a sense of the small imitating the large, which suggests hierarchy, but isn't necessarily hierarchical.) The analogy of organ to body also extends to the relationship of a living being as a system that might resemble an
ecosystem consisting of several living beings; physiology is thus hierarchically nested in
ecology.
Physics
In
physics, the
standard model of reasoning on the nature of the physical world decomposes large bodies down to their smallest
particle components. Observations on the subatomic (particle) level are often seen as fundamental constituent axioms, on which conclusions about the atomic and molecular levels depend. The relationships of energy and gravity between celestial bodies are, in turn, dependent upon the atomic and molecular properties of smaller bodies. In
energetics,
energy quality is sometimes used to quantify energy hierarchy.
Language and semiotics
In
linguistics, especially in the work of Noam
Chomsky, and of later
generative linguistics theories, such as
Ray Jackendoff's, words or sentences are often broken down into hierarchies of parts and wholes. Hierarchical reasoning about the underlying structure of language expressions leads some linguists to the hypothesis that the world's languages are bound together in a broad array of variants subordinate to a single
Universal Grammar.
Music
In
music, the structure of a composition is often understood hierarchically (for example by
Heinrich Schenker (1868–1935, see
Schenkerian analysis), and in the (1985) Generative Theory of Tonal Music, by composer
Fred Lerdahl and linguist Ray
Jackendoff). The sum of all notes in a piece is understood to be an all-inclusive surface, which can be reduced to successively more sparse and more fundamental types of motion. The levels of structure that operate in Schenker's theory are the foreground, which is seen in all the details of the musical score; the middle ground, which is roughly a summary of an essential contrapuntal progression and voice-leading; and the background or
Ursatz, which is one of only a few basic "long-range counterpoint" structures that are shared in the gamut of tonal music literature.
The
pitches and
form of
tonal music are organized hierarchically, all pitches deriving their importance from their relationship to a
tonic key, and secondary themes in other keys are brought back to the tonic in a recapitulation of the primary theme.
Susan McClary connects this specifically in the
sonata-allegro form to the feminist hierarchy of gender (see above) in her book ''Feminine Endings'', even pointing out that primary themes were often previously called "masculine" and secondary themes "feminine."
Ethics, behavioral psychology, philosophies of identity
In
ethics, various
virtues are enumerated and sometimes organized hierarchically according to certain brands of
virtue theory.
In all of these examples, there is an asymmetry of 'compositional' significance between levels of structure, so that small parts of the whole hierarchical array depend, for their meaning, on their membership in larger parts.
In the work of diverse theorists such as
William James (1842–1910),
Michel Foucault (1926–1984) and
Hayden White, important critiques of hierarchical
epistemology are advanced. James famously asserts in his work "Radical Empiricism" that clear distinctions of type and category are a constant but unwritten goal of scientific reasoning, so that when they are discovered, success is declared. But if aspects of the world are organized differently, involving inherent and intractable ambiguities, then scientific questions are often considered unresolved. A hesitation to declare success upon the discovery of ambiguities leaves
heterarchy at an artificial and subjective disadvantage in the scope of human knowledge. This bias is an artifact of an aesthetic or pedagogical preference for hierarchy, and not necessarily an expression of objective observation.
Hierarchies in programming
The concept of hierarchies plays a large part in
object oriented programming. For more information see
Hierarchy (object-oriented programming) and
memory hierarchy.
Containment hierarchy
Main articles: containment hierarchy
A containment hierarchy of the subsumption kind is a collection of strictly nested sets. Each entry in the hierarchy designates a set such that the previous entry is a strict superset, and the next entry is a strict subset. For example, all rectangles are quadrilaterals, but not all quadrilaterals are rectangles, and all squares are rectangles, but not all rectangles are squares. (See also:
Taxonomy.)
A containment hierarchy of the compositional kind refers to parts and wholes, as well as to rates of change. Generally the bigger changes more slowly. Parts are contained in wholes and change more rapidly than do wholes.
★ In geometry: {shape {polygon {quadrilateral {rectangle {Square (geometry)|square }}}}}
★ In biology:subsumption hierarchy {animal {bird {bird of prey|raptor {eagle {golden eagle}}}}}
also, compositional hierarchy {population [organisn [biological cell [macromolecule ]]]]
★ The
Chomsky hierarchy in formal languages: recursively enumerable, context-sensitive, context-free, and regular
★ In physics: subsumption hierarchy {elementary particle {fermion {lepton {electron }}}}
also, compositional hierarchy [galaxy [star system [star]]]
Social hierarchies
Main articles: Social hierarchy
Many human
organizations, such as
businesses, churches, armies and political movements are
hierarchical organizations, at least officially; commonly seniors, called "bosses", have more
power than their subordinates. Thus the relationship defining this hierarchy is "commands" or "has power over". (Some analysts question whether power "really" works as the traditional organizational chart indicates, however.) See also
chain of command.
Alternatives
Hierarchies and hierarchical thinking has been criticized by some, as shown above in
Social hierarchies and
Hierarchical nomenclatures in the arts and sciences. Possible hierarchy alternatives include:
Applied
★
Democracy —
Command hierarchy and
Workplace democracy
★
Anarchism as a social/political theory and practice
★
Markets and associated tools such as
contracts and
property
★
Peer-to-peer networks
Theoretic
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Graph (mathematics)
★
Triarchy Theory, which proposes also
Heterarchy and
Responsible autonomy. See
The Three Ways of Getting Things Done.
Footnotes
References
★ Julie Nelson (1992). "Gender, Metaphor and the Definition of Economics". ''Economics and Philosophy'', 8:103–125.
★
Exploration, Exploitation, and Knowledge Management Strategies in Multi-Tier Hierarchical Organizations on SSRN
See also
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Linnaean taxonomy
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Tree structure
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Classes
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Chomsky hierarchy
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Confucianism
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Network theory
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Maslow's hierarchy of needs
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Hierarchy of roads
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Hierarchy of genres
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Heterarchy
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Holarchy
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Unity of command
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Outliner software
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Degrees of consanguinity
External links
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Principles and annotated bibliography of hierarchy theory
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Summary of the Principles of Hierarchy Theory — S.N. Salthe
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Charting Organizational Hierarchy