Ashby's laws: content, definition, features

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Ashby's laws: content, definition, features
Ashby's laws: content, definition, features

In the field of organization theory, the idea of ​​"necessary variety" is used as a key element in the theoretical framework. In relation to the business world at large, Ashby's cybernetic law states that a company's degree of relevance must match its degree of internal complexity in order to survive in a competitive market.


In the field of cybernetics, Ashby formulated the law of necessary diversity in 1956. It can be explained as follows.

Let D1 and D2 be two systems, and V1 and V2 be their respective varieties. The word variety will be used to mean either (i) the number of distinct elements included in one system, or (ii) the number of possible states it can take. For example, the variety of a simple electrical system that can be on or off is 2. System D1 can only be fully controlled by D2 if the latter variation (V2) is equal to or greater than the first variation (V1). OthersIn other words, the number of different states that D2 can enter must be at least equal to the states of the D1 system (D2≧D1).

William Ashby

Three ideas

In publications that refer to Ashby's law of diversity, the following three ideas are very often mentioned:

  • Some of the states the system can assume are undesirable. Therefore, it is necessary to control it.
  • Only variety can control, reduce or absorb itself.
  • To control a system whose variety is in another system, it must be equivalent to V.

Social systems

In the structural-functional school of sociology, W. R. Ashby's law of necessary diversity denotes a pattern of social action aimed at achieving individual and collective goals. More generally, systems analysis defines a system as anything that works towards completion in an active and evolving environment.

Organization theory is another area of ​​application for Ashby's law. She explains how social systems can control complex tasks.


Ashby's Law of Necessary Variety of Effective Management defines organizations as systems that must deal with specific contingencies that shape their structure, technology, and environment. An organization is an identifiable social entity that pursues multiple goals through coordinated activities and relationships.between its members. Such a system is open.

Law of Necessary Variety

Intercultural groups

Workgroups are organizational units. They consist of two or more members. These are intact social systems with clear boundaries. Participants perceive themselves as a group and are recognized as such by others. They perform one or more measurable tasks, participate in several interdependent functions. Teams of specific working groups have a high degree of interdependence among members.

Intercultural groups are made up of members from different cultural backgrounds. Culture refers to the socialization within a group, and often comes down to ethnic or national origins. It can also refer to this phenomenon in any social group: regional, religious, occupational, or based on social class. Team performance is evaluated within the organizational context. The result of collaboration will not be considered satisfactory if the definition of the task does not meet the requirements of the organization.

Intercultural groups

Ashby method

Ashby used state systems to describe processes of interest to him - regulation, adaptation, self-organization, etc. He wanted to deal with nominal, ordinal, interval and cardinal variables. According to Ashby's laws: cybernetics does not consider things, but ways of behavior. It is essentially functional and behavioral. Materiality doesn't matter. The truths of cybernetics are notdue to the fact that they are derived from some other branch of science. Cybernetics has its own fundamentals.

Ashby was especially talented at creating examples to illustrate his theories. For example, he illustrates learning as a movement towards balance by describing how a kitten finds a comfortable position by a fire or learns to catch mice. As an example of the sequence of events, he posted a flowchart on his office door showing the steps, including "knock", "enter", etc.

Ashby was not interested in simple phenomena or unorganized complexity (like gas molecules in a container), but in organized complexity, including brains, organisms and societies. His approach to the study of organized complexity was unusual. Instead of building a more complex structure by assembling components, the scientist decided to look for constraints or interaction rules that reduce the maximum possible variety to the actually observed variety. Ashby's Laws are not examples of constraints that reduce diversity from what can be imagined to what can be observed.

social system


The level of theorizing of Ashby's laws was unusual. His theories lie at the level of abstraction between laws in disciplines such as biology, psychology, economics, philosophy, and mathematics. They are very useful for scientists who are interested in knowing how knowledge in two or more fields is similar. They also help to transfer ideas from one area to another. That's why these theoriesare of great interest to systemists and cyberneticists. They are very good because they are short.

Ashby's laws explain a large number of phenomena using several statements. Although they have been criticized for being tautological. It is noteworthy that the scientist was able to formulate laws that work in many areas. Ashby's general laws become a tool for developing more specific, operationalizable theories in specific disciplines.


One interesting feature of Ashby's work is that it is compatible with second-order cybernetics. To understand his epistemology, it is important to know the terms and definitions he used. What was observed, Ashby called "machine". For him, the "system" is the internal concept of the "machine". It is a set of variables chosen by the observer. Ashby does not directly discuss the role of the observer in science or the observer as a participant in the social system.

Efficient Management


As someone interested in the successful functioning of the brain, Ashby was interested in the general phenomenon of regulation. He divided all possible outcomes into a subset of goals. The task of the regulator is to act in the presence of perturbations so that all results lie within a subset of goals. This is the difference between his theory and Kahneman's theory. Ashby's laws can potentially be defined in organisms, organizations, nations, or any other entity of interest.

There are different types of regulators. Witherror control can be very simple, such as a thermostat. A cause-driven regulator requires a model of how the machine will respond to a disturbance. One of the consequences of the scientist's view of regulation is the theorem of Conant and Ashby: "every good regulator of a system must be a model of this system." Von Foerster once said that Ashby gave him the idea when he was starting his research in cybernetics.


For Ashby, learning involved adopting a pattern of behavior consistent with survival. The scientist distinguished it from genetic changes. Genes directly determine behavior, while genetically controlled behavior changes slowly. Training, on the other hand, is an indirect method of regulation. In organisms capable of it, genes do not directly determine behavior. They simply create a universal brain that is able to acquire a pattern of behavior during the life of the organism. As an example, Ashby noted that the wasp's genes tell it how to catch its prey, but the kitten learns to catch mice by chasing them. Consequently, in more advanced organisms, genes delegate some of their control over the organism to the environment. Ashby's Automated Self-Strategist is both a blind automaton that goes into a steady state where it stays, and a player that learns from its environment until it is defeated.

Ashby's Laws in Biology


As a psychiatrist and director of a psychiatric hospital, Ashby was primarily interested in the problem of adaptation. In his theory, in order for the machineconsidered adaptive, two feedback loops are needed. The first feedback loop works often and makes small adjustments. The second cycle works infrequently and changes the structure of the system when the "essential variables" go beyond the limits necessary for survival. As an example, Ashby suggested the autopilot. A conventional autopilot simply keeps the aircraft stable. But what if the mechanic misconfigured the autopilot? This could cause the plane to crash. On the other hand, a "super stable" autopilot will detect that the underlying variables are out of range and will begin to readjust until stability returns or the aircraft crashes. Whichever comes first.

The first feedback loop allows an organism or organization to learn a behavior pattern appropriate to a particular environment. The second loop allows the organism to perceive that the environment has changed and that a new behavior needs to be learned.


The effectiveness of Ashby's laws is illustrated by the great success of quality improvement methods in the field of management. Probably no set of managerial ideas in recent years has had a greater impact on the relative success of firms and the competitiveness of countries. This success is evidenced by the international recognition of the ISO 9000 standard as the minimum international management model and the creation of quality improvement awards in Japan, the US, Europe and Russia to identify the best companies to follow. The main idea of ​​quality improvement is that the organizationcan be viewed as a set of processes. The people who work on each process should also work on it to improve it.

Ashby's laws in psychology


Ashby defined "intelligence" as appropriate selection. He asked the question: "Can a mechanical chess player outplay his designer?" And he answered it by saying that a machine could surpass its creator if it could learn from its environment. In addition, intelligence can be enhanced through the hierarchical arrangement of regulators. Lower level controllers perform specific tasks for a long time. Higher level regulators decide which rules lower level regulators should use. Bureaucracy is an example. Gregory Bateson said that cybernetics is a substitute for little boys because in the old days they were given the task of throwing another log on the fire, turning over an hourglass, etc. Such simple regulatory tasks are now usually performed by machines that are designed using ideas cybernetics.

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