International Encyclopedia of Systems and Cybernetics

Any diagnosis reflects necessarily the specific viewpoint and aims of the observer. However some general guidelines are useful in all cases.

The most difficult stage is probably the first one, i.e. symptoms detection, for the following reasons:

- We see that what we are looking for, what we are prepared to perceive in accordance with our past experience, while we tend to remain blind and deaf to anything else;

- We have a very imperfect perception of time scales, i.e. of the differences between short, medium and long term processes;

- We mostly lack the capacity to perceive complex interrelations and frequently miss to perceive even the most obvious and critical ones (see FRANÇOIS' s study of Manmade disasters – 1989b).

All this adds up to De ZEEUW's invisibility and FOURASTIÉ's ignorance of ignorance.

Once the symptoms partly or totally observed, we must understand their meaning, trying to sort out the subjective part of our interpretations. This search for meaning should also be creative by forming hypotheses about the possible interrelations between symptoms and by searching for other clues in apparently unrelated areas, without of course overextension (in itself a subjective criterion) of this inquiry.

Finally, it may be useful to construct a formal model of our diagnosis. This is however also a risky endeavor, since formal modelization is subject to rules whose use mayor may not distort the observed situation.