p.1 The objective of this paper is to analyse some of the conceptual and methodological contributions that complexity theory can make to the study of socio-technical cooperative systems... we will show how the concept of complexity can improve the methods of modelling and the design [of] socio-technical systems.

p.2 A complex system is a system for which it is difficult, if not impossible to reduce the number of parameters or characterising variables without losing its essential global functional properties.

p.2 Four specific properties of complex systems will be discussed in relationship to their usefulness to socio-cognitive modelling:

Property 1: non-determinism

A complex system is fundamentally non-deterministic. It is impossible to anticipate precisely the behaviour of such systems even if we completely know the function of its constituents.

Property 2: limited functional decomposability

A complex system has a dynamic structure. It is therefore difficult, if not impossible, to study its properties by decomposing it into functionally stable parts. Its permanent interaction with its environment and its properties of self-organisation allow it to functionally restructure itself.

Property 3: distributed nature of information and representation

A complex system possesses properties comparable to distributed systems (in the connectionist sense), i.e. some of its functions cannot be precisely localised.

Property 4: emergence and self-organisation

A complex system comprises emergent properties which are not directly accessible (identifiable or anticipatory) from an understanding of its components.

p.2 Non-determinism of socio-cognitive processes is often considered as being due... to a disturbance of the system as a result of unforeseen causes

p.3 A truly complex system cannot be represented by combining a collection of well defined functional components. A principal obstacle to the functional decomposability of complex systems is the dynamic and fluctuating character of their constituent functions. The interaction with the environment, as well as the learning and self-organisation mechanisms makes it unrealistic to regard such systems as structurally stable.
 An interesting property of socio-technical systems is their capacity to reorganise rapidly their functional structure.

p.7 Intuitively, a property is emergent when it can not be anticipated from knowing how the components of the system function. Emergence is not due to incomplete information regarding the components of the system, but to the non-linear and distributed character of the interactions... If a system is capable of self-organisation, its functions evolve over time so that they can respond better to the requests of its environment. In this sense, a complex self-organised system cannot be described as functionally stable.

p.8 The classical analytical reductionist approach is particularly weak in explaining the emergence of functional properties, despite the fact that in socio-technical complex systems, the strength of the collective lies in such properties.