Definition: System and 5 Conditions

Source of Definition

The definition below comes from Russell Ackoff in the following book:

Earlier versions of the definitions are found in the following paper

Additional information about the understanding of systems using this definition:

Definition: System and 5 Conditions

Russell Ackoff Definition: System: A system is a whole consisting of two or more parts that satisfies the following five conditions:

  1. The whole has one or more defining properties or functions
  2. Each part of the set can affect the behavior or properties of the whole
  3. There is a subset of parts that is sufficient in one or more environments for carrying out the defining function of the whole; each of these parts is necessary but insufficient for carrying out this defining function.
  4. The way that each essential part of a system affects its behavior or properties depends on (the behavior or properties of) at least one other essential part of the system.
  5. The effect of any subset of essential parts on the system as a whole depends on the behavior of at least one other such subset.

Definition: Environment

Definition: Environment: The environment of a system consists of those things that can affect the properties and performance of that system, but over which it has no control.

That part of its environment that a system can influence, but not control, is said to be transactional. Consumers and suppliers, for example are part of a corporation's transactional environment.

That part of a system's environment that can neither be influenced nor controlled is said to be contextual, for example, the weather and other natural events, such as floods and earthquakes, and in the case of a corporation, at least come competitive behavior.