The terms emergence and emergent behavior are increasingly being used in SoS contexts. While the concept of emergence and its derivative terms has a long history in science and technology, to this day there is no single, universal definition of emergence.

The concept is often illustrated, however, by examples such as the following:

  • The behavior of a human brain cannot be known or predicted from a detailed knowledge of the neurons that comprise it.
  • The social behavior of a bee population is not predictable from knowledge about individual bees.
  • The way in which any given human culture puts together words and rules of grammar is not predictable from knowledge about the alphabet it uses.

In SoS contexts, the recent interest in emergence has been fueled, in part, by the movement to apply systems science and complexity theory to problems of large-scale, heterogeneous information technology based systems. In this context, a working definition of emergent behavior of a system is behavior which is unexpected or cannot be predicted by knowledge of the system’s constituent parts.[1]

Another point of view is that SoS show emergent attributes, such as execpected structures and behaviours.[2]

Generally, emergence is reached by collaboration of the constituent systems within the SoS which is necessary to adress the uncertain environment an SoS typically is operating in. This goes so far, that even the actual state of an SoS can be impossible to grasp at a moment of time due to its complexity.
SoS takes place in environments where uncertain factors caused by people can occur and directly influence the system. The System of Systems then automatically adapts its behaviour to the new situation.



  1. US Department of Defense, Systems Engineering Guide for Systems of Systems, 2008
  2. Sauser, Boardman, 2008.


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