International Encyclopedia of Systems and Cybernetics

René DESCARTES stated in the following way the four precepts which are basic according to him for one to "conduct correctly his reasoning and seek truth in the sciences":

"… never to accept anything for true which I did not clearly know to be such;

"… to divide each of the difficulties under examination into as many parts as possible, and as might be necessary for its adequate solution.

"… To conduct my thoughts in such order that, by beginning with objects the simplest and easiest to know, I might ascend by little and little, and, as it were, step by step, to the knowledge of the more complex; assigning in thought a certain order even to these objects which in their own nature do not stand in a relation of antecedence and sequence.

"… in every case to make enumerations so complete, and reviews so general, that I might be assured that nothing was omitted." (1947, p.175-6) (Translation by Saxe COMMINS and Robert N. LINSCOTT, 1947).

This famous text certainly justifies some comments from a systemic viewpoint:

1. DESCARTES "seeks truth", but the hereafter quoted sentence seems to show that his model of "truth" is geometry's one, i.e. the truth of an abstract conceptual construct, or in other words, a model or, at most, an algorithm. The problem of ontological truth is not solved (neither is it by systemics, but at least, it is clearly stated: reality is "veiled" (B. d'ESPAGNAT, 1985)

Immediately after enouncing his four precepts, DESCARTES says: "The long chains of simple and easy reasonings by means of which geometers are accustomed to reach the conclusions of their most difficult demonstrations, had led me to imagine that all things, to the knowledge of which man is competent, are mutually connected in the same way, and that there is nothing so far removed from us as to be beyond our reach, or so hidden that we cannot discover it…" (p.176)

2. The word "clearly" (in DESCARTES text in French: "évidemment" = "evidently") and, of course, the whole of the first precept, places DESCARTES, just as anyone of us, in the observer's position, that he does not examine. Moreover, DESCARTES was not able – as we ourselves are now – to distinguish "evidence" by direct perception and "evidence" technically constructed (as for example when physicists use a particles accelerator).

Finally, the notion of "evidence" becomes quite nebulous when it refers to the human affairs, unavoidably scrutinized by observers, quite different from each other psychologically and culturally. Inevitably, rationality becomes more or less subjective and tainted by values.

3. The second precept contains the seeds of the whole reduccionist research method, of extraordinary efficiency when applied to reducible phenomena, but which inconveniently eliminates the complex interactions between elements and processes.

4. The third precept tends to obviate this inconvenient, but the experience of three and half centuries shows that complex interactions generally cannot be again pieced together in such a way and thus remain ignored.

The last part of this precept shows that DESCARTES was conscious of the multicausality problem as well as the one about simultaneity. However, he does not say us how his "thought assignment" may lead to the discovery of this order, of which he reasonably presumes the existence.

5. The last precept cannot, unfortunately, guarantee us that we did not omit something. Moreover, while it seems to herald the statistical method, it does not contain anything related to the reduction of variety by way of statistics.