International Encyclopedia of Systems and Cybernetics

R.L ACKOFF states: "Nature is not disciplinary. The phenomena and the problems which nature presents to us are not divisible into disciplinary classes. We impose scientific disciplines on nature; it does not impose them on us. Some of the questions that we ask of nature - in contrast to the problems it presents to us – can be classified as physical, chemical, biological, and so on; but not the phenomena themselves… For example automobile accidents can be viewed at least as physical, biological, psychological, sociological, and economic phenomena. To study them in anyone of these ways is to exclude variables relevant from other paints of view" (1964, p.54).

This is of course not an anti-disciplinarian stand, but merely a caveat about reductionist blinders.

G. KLIR observes: "As a result of arguments pursued by systems science for decades, scientist are now becoming, in general, more sensitive to the limitations of their own disciplines. They tend to be considerably more aware now than a few decades ago that significant real-world problems involve almost always aspects that transcend disciplinary boundaries" (1993,p.51).

The subject of interrelations in-between specialized scientific disciplines is quite a difficult one. While the more generic term of cross disciplinarity is frequently used, we propose the following distinctions in order to avoid the semantic muddle and the practical confusion which characterizes it.

Interdisciplinarity: indicates a specific interrelation between two disciplines. Some examples could be: biochemistry, agrobiology, paleobotanics, astrophysics or astrodynamics and, in a somewhat extended sense economic history, population genetics or the comparative study of natural and artificial neural nets.

Multidisciplinarity: relates to a type of collective study of some complex project, in which specialists in numerous different fields must collaborate. Some examples are: the participation of economists, financiers, lawyers, engineers, geologists, agronomists, hydrologists, etc. into the planning of a great hydropower dam and irrigation scheme; or the global study of climate by meteorologists, oceanographers, physicists, chemists, vulcanologists, botanists, ecologists, etc.

Transdisciplinary: qualifies a set of general methodologies and modelization tools better adapted to study the numerous interactions and feedbacks within complex systems, as well as their significant exchanges with their specific environment. It applies to the same type of projects or situations studied by multi disciplinary endeavors, but it contributes tools for reciprocal understanding, discovery of hitherto unperceived interfaces and integrating synthesis

Interdisciplinarity: does not per se present many difficulties. It implies generally the bridging of two disciplines because one needs of the other or one brings new insights to the other. The astrophysicist, for example interpretes astronomical discoveries in physical terms and normally has an excellent knowledge of both fields and of the mathematics needed as lingua franca.

Multidisciplinarity: on the contrary brings along quite a number of misunderstandings. It reflects the ever growing need for collaboration among many (and very diverse) disciplinary specialists for the planning or the management of complex systems. Unfortunately, most of multidisciplinary meetings – especially those which must produce some critical decisions about practical projects – lead only to confusing misunderstandings and quite frequently to awful "messes" (in R. ACKOFF's words) and costly man-made disasters.

Transdisciplinarity implies:

1. The existence of a meta-level of models and concepts, leading to an integrated synthesis, constructed and understandable by all the stakeholders of the system under study (even those whose opinion has not been asked for).

2. The existence of a common meta-language, based on isomorphies and useful to convey synthetic perception of complex wholes and intricate meta-models.

No biologist will become an engineer, nor a geographer an economist, but they may thus reach a better mutual understanding, learn to ask "good questions" and to provide answers, meaningful not only for themselves.

General systemic and cybernetic concepts are preferred tools for transdisciplinarity

→ the three corresponding specific headings.