International Encyclopedia of Systems and Cybernetics

"Unless some threshold level of complexity is reached, there can be no evolution of greater complexity; below this threshold, systems degenerate" (H. PATTEE, 1972, p.35).

It would have been better to call this principle: "Principle of complexity threshold"

While this principle is thus enounced by PATTEE, this author expresses his debt to J. von NEUMANN, who wrote (in 1956): "We are all inclined to suspect in a vague way the existence of a concept of "complication". This concept and its putative properties have never been clearly formulated. We are, however, always tempted to assume that they will work in this way. When an automaton performs certain operations, they must be expected to be of a lower degree of complication that the automaton itself… That is, if A can produce B, than A, in some way must have contained a complete description of B. In order to make it effective, there must be, furthermore, various arrangements in A that see to it that this description is interpreted and that the constructive operations hat it calls for are carried out. In this sense, it would therefore seem that a certain degenerating tendency must be expected, some decrease in complexity as ne automaton makes another automaton" (1956, p.2092).

An obvious consequence of this concept is the necessity for combinatory heterogeneity (genetic, sexual, social, etc… ) if complexity is to be produced and extended.

An other consequence is that any autopoietic system must contain a permanently usable "blueprint" or template of itself.

On the other hand, PATTEE himself comments, however, that: "The scientific description of events would, in fact, get nowhere in nature's maze of complexity unless there were repeated resimplifications which we call hierarchical levels of description" (Ibid., p.37).

As shown by J. MILLER in his "Living Systems", for example, systemic isomorphisms appear throughout the various levels of description.