Structural and quantitative characteristics of complexity in terms of information

Issues related to overcoming or controlling complexity accompanied entire intellectual development of humanity, although originally stress was on its opposition - simplicity. This paper reviews various conceptualizations of complexity in the European philosophical and scientific tradition from Pre-Socratic thinkers of Antiquity to the present time. Special focus is on the contributions of Aristotle whose works shaped the view of reality of his followers, as well as of his adversaries. However, many, if not majority of significant developments in the studies of complexity and simplicity are at least briefly described. This historical perspective is used for a critical summary of the ways complexity is studied today and for an attempt to provide a unified conceptual framework for the various modes of complexity considered in the past. For this purpose, the author uses his earlier developed general concept of information as an identification of a variety and concepts characterizing it. Finally, a quantitative description in the form of two related to each other measures of complexity and of information integration is presented.