The first paradigm was the traditional Aristotelian one, based on the doctrine of the Four Causes. This is the one which, in some form, most non-cyberneticians still believe in today, but which gives rise to many well-documented difficulties. This first paradigm uses the classical one-domain mechanisms of matter and energy only. These were traditionally seen as being inconsistent with teleology, from which it was believed to follow that purposive behaviour necessitated something non-mechanistic-perhaps even some form of reverse causality.
The second paradigm was the one developed by Rosenblueth, Wiener and Bigelow, and by the Josiah Macy Conferences. This adds a second domain, that of information, to that of classical physics, and it is this two-domain paradigm which most cyberneticians believe in. This one uses two-domain mechanisms, in which information is expressed by circular flows of energy, which return the information to the input as feedback. This second paradigm also gives rise to problems with purposiveness, which have persisted as unfinished business ever since cybernetics began.
The most far-reaching theoretical implication of recognising the importance of the discontinuity between information and imparity is the suggestion that the same operation should be performed again, this time adding a third domain to the two already recognised.
Stewart, D J (1999a). The implications for cybernetics of the discontinuity between information and imparity. Proc. 15th Int. Congress on Cybernetics, Namur (Belgium), September 1998, 949-954.