The terms hierarchy and heterarchy describe two distinct and basic organizational principles. A hierarchy is a structured arrangement of systems forming a perceived vertical pattern where smaller, more specific parts are nested within larger more generic systems. A heterarchy defines a more informal pattern of organization where member elements may be without formal positions or where positioning is dependent on context.
Hierarchy theory describes the emergent pattern of organization where smaller subsystems form part of larger systems which in turn form part of larger suprasystems. The term hierarchy is here used to refer to the overall emergent structure of systems; thus it is used in a slightly more abstract fashion than the common understanding of it as a stratified social structure.
Central to hierarchy theory is the attempt to provide a framework for considering relationships among levels and their ordering according to emergent processes that form nested, multi-leveled structures; also called integrative levels. This emergent, nested structure of integrative levels can be found in virtually all systems whether physical, chemical, biological, social or engineered.1
Hierarchical organizations express a nested structure of organization, where any system, always – except at the lowest level – contains more than one subsystems nested within it, and where all subsystems are embedded within larger systems – except at the highest level. In systems analysis, it is typical to term the components of a system “subsystems” and to refer to the larger system surrounding the entity under consideration as the “suprasystem.”2 Nested elements are embedded within larger systems. Here embeddedness refers to the degree to which an activity, a relation, an organization, etc. is influenced by the suprasystem or environment within which it is embedded.3
Likewise, a hierarchical structure denotes a ranking arrangement in which the nature of functions at each higher level becomes more broadly embracing than at the lower level.4 For example, within a socio-economic system such as a corporation, members at higher levels are required to perform functions that affect the entire organization, while those at a lower level perform functions that have an impact on a narrower scope of activity. Likewise, these higher level functions are typically more abstract, in that they relate to many different subsystems while functions performed at a lower level are typically more concrete, having immediate application in affecting some discernible outcome.
The higher, broader levels are occupied by processes with relatively slow-moving, low-frequency behavior, which are sometimes spatially larger, and serve as the context for finer, or lower level structure and activity.5 In ecology, these macro-level processes of change are called slow variables.6 For example, the moving of tectonic plates is a high-level slow variable within which many other lower level ecosystems processes take place much faster, but which ultimately are conditioned by these macro level slow variables.
Although each level in an emergent hierarchy has its own internal rules and dynamics, there is, empirically, often similar patterns in the dynamics and processes of the different levels. The same types of patterns and organization can be found in systems belonging to different levels. It is these emergent patterns and structures that remain invariant across different levels and systems that is the primary interest of systems theory. For example, all open systems have a pattern of interrelationships, inputs and outputs, functional processes, etc. The cells in the body of an animal need food and energy to metabolize in the same way that the animal’s body as a whole needs food and energy. The material building blocks on different levels may be different but the overall patterns and functioning remain invariant, one classical example of this being fractal structures.7
The encyclopedia Principia Cybernetica expresses this well when they write: “Thus we find similar structures and functions for different systems, independent of the particular domain in which the system exists. General Systems Theory is based on the assumption that there are universal principles of organization, which hold for all systems, be they physical, chemical, biological, mental or social. The mechanistic worldview seeks universality by reducing everything to its material constituents. The systemic world view, on the contrary, seeks universality by ignoring the concrete material out of which systems are made, so that their abstract organization comes into focus.”8
The term heterarchy was first used in a modern context by the cybernetician McCulloch. In his work in psychology he looked at different cognitive structures, the organization of which he termed heterarchy. He illustrated how human cognition while exhibiting orderly patterns, was not organized hierarchically. This understanding transformed the study of cognition and led to breakthroughs in the field of computation.9 A heterarchy is a pattern of organization where the elements in the structure are unranked or may be ranked a number of different ways.10 In social and information sciences, heterarchies are networks of elements in which each element shares the same “horizontal” position of power and authority, each playing a theoretically equal role.11 The anthropologist D. Bondarenko definitions heterarchy as “the relation of elements to one another when they are unranked or when they possess the potential for being ranked in a number of different ways.” He explains that it is therefore not exactly the opposite of hierarchy, but is rather the opposite of homoarchy, which is itself defined as “the relation of elements to one another when they possess the potential for being ranked in one way only”.12
Whereas hierarchies sort groups into progressively smaller categories and subcategories, heterarchies may divide and unite groups in various ways, according to multiple concerns that arise according to perspective.13 Thus the hierarchical pattern as a taxonomy or conceptual principle of organization can be associated with objectivism – the idea that there is one single objective reality – with the hierarchy representing the fixed set of relations within this monolithic ordering pattern. Inversely heterarchy, as a conceptual organizational principle, can be seen to reflect a more constructivist epistemology, in that it incorporates the idea of different contexts creating different perspectives and thus different organizational structures.
Within a heterarchical organizational paradigm changing the question can potentially change the ordering of levels. For example, we can look at an ecosystem or social organization according to a number of different criteria such as age, sociability, income, social mobility, etc. each of which would give a different organizational structure.14 For example, four countries might be the same size but base their importance on different factors: one on economic factors, one cultural the other military, etc. Each, would then, be ranked differently depending on the context.
Thus hierarchical organizations are context dependent, exhibiting different structures depending on the context. This may be purely regarding the conceptual framework and questions that we are asking but also may be with respect to the real structure to the system. For example, a social group may opt for a flexible organization where whoever is best able to respond to the particular needs placed on the organization is given the authority and responsibility to lead.
The relationship between hierarchical and heterarchical structures of organization is not a simple dichotomy but complex in nature as both contain elements of each other. For example, the hierarchies within social systems are expected to reflect the idea that some people are better able to deal with a situation than others, and those people will be ascribed roles of leadership. When they fail to meet the demands of these roles they will be expected to be replaced by others that can, which is an expression of the fluid context-dependent nature of a heterarchy. Likewise, heterarchies may sometimes ascribe positions of responsibility and authority to those who are best able and – at least for a brief period of time – may form some kind of hierarchy to execute.
A heterarchy may form parallel to a hierarchy, form part of a hierarchy, or may themselves contain hierarchies within them; the two kinds of structure are not mutually exclusive. In fact, each level in a hierarchical system may be seen to be composed of a potentially heterarchical group which contains its constituent elements.15