Cybernetics had from the beginning been interested in the similarities between autonomous, living systems and machines (see history of cybernetics). In this post-war era, the fascination with the new control and computer technologies tended to focus attention on the engineering approach, where it is the system designer who determines what the system will do. However, after the control engineering and computer science disciplines had become fully independent, the remaining cyberneticists felt the need to clearly distinguish themselves from these more mechanistic approaches, by emphasizing autonomy, self-organization, cognition, and the role of the observer in modelling a system. In the early 1970's this movement became known as second-order cybernetics.
They began with the recognition that all our knowledge of systems is mediated by our simplified representations--or models--of them, which necessarily ignore those aspects of the system which are irrelevant to the purposes for which the model is constructed. Thus the properties of the systems themselves must be distinguished from those of their models, which depend on us as their creators. An engineer working with a mechanical system, on the other hand, almost always know its internal structure and behavior to a high degree of accuracy, and therefore tends to de-emphasize the system/model distinction, acting as if the model is the system.
Moreover, such an engineer, scientist, or "first-order" cyberneticist, will study a system as if it were a passive, objectively given "thing", that can be freely observed, manipulated, and taken apart. A second-order cyberneticist working with an organism or social system, on the other hand, recognizes that system as an agent in its own right, interacting with another agent, the observer. As quantum mechanics has taught us, observer and observed cannot be separated, and the result of observations will depend on their interaction. The observer too is a cybernetic system, trying to construct a model of another cybernetic system (see constructivism). To understand this process, we need a "cybernetics of cybernetics", i.e. a "meta" or "second-order" cybernetics.
These cyberneticians' emphasis on such epistemological, psychological and social issues was a welcome complement to the reductionist climate which followed on the great progress in science and engineering of the day. However, it may have led them to overemphasize the novelty of their "second-order" approach. First, it must be noted that most founding fathers of cybernetics, such as Ashby, McCulloch and Bateson, explicitly or implicitly agreed with the importance of autonomy, self-organization and the subjectivity of modelling. Therefore, they can hardly be portrayed as "first order" reductionists. Second, the intellectual standard bearers of the second order approach during the 1970's, such as von Foerster, Pask, and Maturana, were themselves directly involved in the development of "first order" cybernetics in the 1950's and 1960's. In fact, if we look more closely at the history of the field, we see a continuous development towards a stronger focus on autonomy and the role of the observer, rather than a clean break between generations or approaches.
Reference:
Heylighen F. & Joslyn C. (2001): "Cybernetics and Second Order Cybernetics", in: R.A. Meyers (ed.), Encyclopedia of Physical Science & Technology , Vol. 4 (3rd ed.), (Academic Press, New York), p. 155-170