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Complexity ( Latin complexum , past participle from complecti “wrap around”, “include” or “summarize”) describes the behavior of a system or model , the many components of which can interact with each other in different ways, only follow local rules and to which instructions from higher levels are unknown . The term is a compound from the Latin preposition cum “with”, or “together with” and plectere “braid” or “ interweave ” in the sense of “interwoven”.

If the overall behavior of a system cannot be clearly described , despite complete information about its individual components and their interactions , then it is a question of emergence .


The term is defined differently depending on the author and the scientific field.

The economist Peter Ulrich describes the complexity of a situation with the variety of influencing factors and the extent of their mutual interdependencies and characterizes these as a characteristic of badly structured decision-making situations . Complexity is a possible form of the opposite of simplicity , determinability and clarity.

The complexity of an issue is reflected by the amount of details that differ from all other details of the issue in such a way that there is no simplifying abstraction that reduces the level of detail. Complexity is also created by contradicting objectives, dilemmas and the indeterminable behavior of autonomous system units and is an essential characteristic of social , societal and cultural systems.

  • In systems theory , complex systems are described by a number of characterizing properties. The complexity of a system increases with the number of elements, the number of links between these elements and the functionality and unmanageability of these links (e.g. non-linearity).
  • Dealing with economic, organizational and technical complexity belongs to the topic of complexity management ( complexity reduction ). But even coping with everyday life today requires techniques of complexity management such as exact scheduling, conscious selection from many available options - e.g. B. of television programs through a program guide - or even the purchase of complete problem solutions from professional consultants.

If the impression of complexity in the first instance reflects a perception difficulty because the number of possible connections in a system is no longer manageable and the causality between them is no longer recognizable, this can have two causes: lack of dependencies and order in the external world ( ontological complexity) and excessive demands of the human means of perception through the multitude and variety of existing dependencies and order ( epistemological complexity).

Closely related pairs of opposing terms of ontological and epistemological complexity are the terms “unorganized complexity” and “organized complexity” proposed by Warren Weaver .

  • Limits of Definability

There are views that the term “complexity” is autological , that is, that it can be related to itself: the concept of complexity is itself complex.

Study areas

Development of complexity

Complex systems have structural and functional as well as dynamic properties. The dynamic properties manifest themselves primarily in the processes that lead to their creation. These processes are i. d. R. emergent and self-organized. Every emergent process creates systems of higher complexity from elements that interact with one another. Emergent processes are mostly dissipative and autocatalytic and therefore non-linear . Its course is determined by the deterministic chaos. Due to the non-linearity of the processes, structures and systems are formed. The processes are influenced by the conditions in their environment.

Examples of self-organized structures in inanimate nature are Rayleigh-Bénard convection , in which stable convection cells are generated by a heat flow, and the Belousov-Zhabotinsky reaction , in which stable patterns or regular color changes are generated by an autocatalytic partial process.

Since nature and society have developed in successive and hierarchically building on emergent processes over the course of time, the complexity of the world, which has grown steadily since the hypothetical Big Bang, has developed by itself.


Joseph Tainter argues that the ability in primitive societies to solve problems B. to solve the scarcity of resources simply through migration (through horizontal expansion), does not exist in settled, developed and complex societies. A "vertical" solution has to be found here, i. H. Develop a higher form of hierarchical control, i.e. raise more taxes, take refuge in formalisms, enlarge the bureaucracy or the army, favor the elites even more, etc. This creates a spiral of growing complexity and increasing complexity costs, with investments in increasingly complex ones Problem-solving strategies achieve a falling return per investment unit. At this point, a social collapse even makes sense; it leads to a streamlining process.

According to Friedrich von Hayek , the complex structures of human society and the associated non-linear sociodynamics arise on the one hand spontaneously within the framework of self-organized, emergent social processes and on the other hand as the result of a conscious social design. The latter starts with a certain structure, but then develops in a self-organized manner through the spontaneous social processes. He called this combination of conscious design and self-organized further development the "extended order of human interaction".


The complexity of organizations increases, according to the theory of organization with the extent of their functional differentiation and the related division of labor , growth, specialization, professionalization and decentralization. This also increases the diversity of the information and action programs available in the organization for handling external events (e.g. markets, politics) and internal organizational environment (subjectivity of employees). Uncontrolled complexity in an organization leads to inefficiencies, inhibits innovation, ties up resources in unproductive bureaucratic processes and increases costs. Too little complexity of an organization in relation to the complexity of its environment also leads to functional deficits.

System differentiation through the formation of sub-systems represents an attempt to reduce the complexity that they deal with; at the same time, however, it increases the overall complexity of the organization.

Large-scale systems

Charles Perrow analyzes from a sociological perspective the attempts to make complex and risky (large) technologies safer, using a few concise examples (e.g. radar , nuclear power plants ) and shows that the measures that are aimed at reducing risks through installation or retrofitting mastering safety technology, often only lead to a further increase in complexity and uncontrollable interactions of elements in a confined space ("tight coupling"). So solved z. For example, the introduction of radar in its early days resulted in more and more evasive reactions in ship traffic, which further increased the mutual unpredictability of ship movements.

Computer science

In theoretical computer science , complexity theory describes a concept for estimating the resources required for the algorithmic treatment of certain problems . The complexity is high when, on the one hand, very many and, on the other hand, very complicated details have to be dealt with.


Due to technical progress, the complexity of technical products has increased significantly, in particular due to the integration of electronic control units . Up to 50 control units are installed in a vehicle today, which are networked and communicate with one another. At the same time, this also increases the complexity of the technical documentation and results in an increased complexity of production planning and control .

See also


Web links

Individual evidence

  1. complex. Duden online , accessed on September 28, 2013 .
  2. ^ A b Steven Johnson: Emergence: The Connected Lives of Ants, Brains, Cities . Scribner, New York 2001, ISBN 3411040742 , p. 19.
  3. ^ Duden editors: Duden, The dictionary of origin . Etymology of the German language. 4th edition. tape 7 . Bibliographisches Institut (Dudenverlag), Mannheim 2006, ISBN 3-411-04074-2 .
  4. ^ P. Ulrich, E. Fluri: Management . Haupt, 1992, ISBN 3-258-04370-1
  5. P. Milling: System-theoretical basics for planning corporate policy . Berlin: Duncker & Humblot, 1981, ISBN 3-428-04931-4
  6. ^ Vittorio Ferretti: Back to Ptolemaism - To Protect the Human Individual from Abuses of Social Constructs . Amazon / Kindle, 2012.
  7. ^ Warren Weaver: Science and Complexity . In: American Scientist . 36, No. 4, 1948, pp. 536-44. PMID 18882675 . Retrieved November 21, 2007.
  8. Luhmann 2005: 255. quoted from Dijana Tavra: Trust as a mechanism for reducing complexity - summary. (PDF; 79 kB) (No longer available online.) University of Bern, excellent essays , 2009, archived from the original on November 26, 2013 ; accessed on September 28, 2013 (presumably the link to the previous link Luhmann 2005 , which is no longer available ). Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot /
  9. Günter Dedié: The Power of Natural Laws - Emergence and Collective Abilities from Elementary Particles to Human Society, 2nd edition, tredition 2015
  10. ^ Joseph Tainter: The Collapse of Complex Societies. Cambridge University Press 1990, p. 128 ff.
  11. ^ Friedrich von Hayek: The fatal arrogance - the errors of socialism, Mohr 2011
  12. ↑ In summary: Charles Perrow : Complex Organizations: A Critical Essay. Echo Point Books & Media, 2014 new edition, ISBN 978-1626549029 .
  13. Niklas Luhmann: Social systems: outline of a general theory. Suhrkamp, ​​Frankfurt am Main 1987, p. 38
  14. ^ Charles Perrow: Normal Accidents: Living with High Risk Technologies. Princeton University Press, 1999 reprint, ISBN 978-0691004129 .