The three volumes comprising Nature, Cognition and System present a representative collection of reports on current research in the major topics of system theory and cybernetics as applied to the two main classes of systems, viz. the natural and cognitive systems. The contributions emphatically present alternative reflections and creative syntheses of such time-honoured and controversial issues of the nature-cognition-system connection' which in principle and in fact form the very subject-matter of the current sciences of complexity'. In the present volume Niels Bohr's seminal idea of complementarity' has been chosen as the hinge around which these discussions, critical appraisals, alternative views, and applications, both orthodox and non-orthodox have taken place. This pivotal notion seems to exert an appeal not only upon the strictly technical or disciplinary aspects of quantum physics, but also upon the wider epistemological understanding, which is based on the role and nature of language for measurement processes, that Bohr himself seemed to apply to subjects other than physics, and which later might turn out to be of primary importance for an explanation in genuine system-scientific context. Volume II is organized into three parts. The first part contains contributions which have been written quite in the true spirit of the Copenhagen Interpretation. The second one contains those with a quite pronounced critical mood towards the orthodox theory, including the discussions among others of the problematic issues of physics and cognitive science. The third part is dedicated to the discussions of this complex nature-cognition-system connection' from the non-orthodox point of view. Thescope and depth of the contributions reveal an underlying coherence, despite the divergence in the approaches to the study of the subject, thus making this volume a useful source for researchers, practitioners, teachers and students of the variety of disciplines making up modern system theory, cybernetics and cognitive science.

is both a player and a spectator, is explained here illuminatingly. With regard to logical ambiguities and paradoxes, which may show up in all these topics, he, like Locker, is of the opinion that, philosophically speaking all apory of a lower level have to be accepted an a higher level of thinking. After the above expositions of a more general purport we turn now to two contributions which are particularly focused on Bohr's concept of complementarity. First is the article of Hilgevoord who briefly and non-technically describes a short curriculum vitae of the concept beginning with Planck through Bohr to Heisenberg and Schrodinger. Included in this short story, of course, is the famous wave-particle duality and the paradox inherent in it many physicists are still saddled with. How this paradox was solved is explained here simply and clearly: first, generally by quantum mechanics where the disturbance theory of measurement was supposed to be of some relevance, and secondly, where this theory is further refmed leading to Bohr's conclusion of the essential unsolvability, and accordingly the completeness, of the statistical element of quantum mechanics. The reading of this short article may arouse questions and surmises whether complementarity has been ruminated by Bohr to tame the law of excluded middle dividing the well-defined content of position measurement from that of momentum measurement, just to mention one. Whatever it may be the idea of complementarity betrays the perplexity of the observing system in dealing with nature's complexity.

usually called the classical (scientific) attitude (according to which there is a dichotomy between nature and cognition) and suggestions for better understanding of their mutual encroach ment. The authors belong more or less to the non-standard systems science, the third order cybernetics, or find themselves already beyond the third stage in the history of artificial intelli 1 gence ). They take the inescapability of the mutual implication of the description of nature and that of cognition seriously. Fourth ly, closely linking up with the previous, it emphatically calls attention to the forgotten microscopic dimension of science. If I am not mistaken we have at this moment reached the historic stage where the tremendous renascence of the mechanistic-structural paradigm, remarkably enough, calls for its functional-dynamic counterparts. The volume strives to respond to this secret trend in various disciplines and to put into words that which is tacitly alive in the minds of the ever increasing number of people in this systemsage. The investigation on the intertwinement of nature and cognition finds itself in this very paradoxical niche structured by those two opposite developments."