Systems science is generally said to have emerged during and after World War II, although there were precursors to the basic ideas. The people who created each school of thought were working largely independently, although many of them knew each other. They came from different disciplines, they were working on different problems, they formulated different variations of the principles of systems and cybernetics, and they often chose to affiliate with different academic societies.

p. 79: Introduction - "The origins and purposes of several traditions in systems theory and cybernetics," 1999