Impact of the Cybernetic Law of Requisite Variety on a Theory of Information Science* **

Search for an integrated, comprehensive theory of information science (IS) has so far been unsuccessful. Appearance of a theory has been retarded by one central constraint, the large number of disciplines concerned with human comnication. Crossdisciplinary interdependence occurs in two ways: theoretical relation of IS phenomena to a given science, and practical relation of the science to IS dissemination of its contributions. We are concerned here with the first. The main difficulty in making IS models is the above mentioned interaction of many sciences of communication. Prominent among these are physics, biology, psychology, library science, computer science, several social sciences, applied ionic and mathematicsand not least, cybernetics. That cybernetics should apply to IS is riot a new idea, But more precision has emerged recently. Cybernetics is now seen to underlie nearly all IS phenomena through two central concepts: variety, and the law of requisite variety. The last (stated by Ashby) provides a quantitative approach to system regulation and control. IS concerns regulatory activity in typically large, goal-seeking systems. That is, propagation of meaningful human messages between sender and recipient on an "IS path" is a pf 1-seeking process. The IS path is biophysically and topologically invariant in space and time It consists in three segments, two within the communicants and one external to both. Within this environmental segment are located the physical artifacts of IS All social structures depend on variation and matching of the central segment. This includes transmission of knowledge and education. The law of requisite variety affects each stage of propagation along an IS path. More specifiLaily, it has shaped all steps in the bibliographic access to knowledge. Applications of the law of requisite variety at interfaces in IS systems are described in references to papers by the author and his students. A quarter of a century ago cybernetics was founded by Wiener, Shannon, Ashby, Beer and many others. In the interval it has become a well developed science. Wiener coined the word "cybernetics" (from the Greek: "steersmanship") to designate the science of "control and communication in the animal and the machine " .1 Fifteen years ago the phrase "information science" was coined to designate an anticipated science looming behind an immense agglomerate of scientific, technical and professional knowledge concerning propagation of human messages. The emphasis on communication overlaps that of cybernetics, and includes all aspects of the way messages are generated, transformed, stored, disseminated, received, and used. The field has far-reaching practical applications (one of which is communication in science). So far, however, the anticipated theoretical science has not appeared. Few or no principles have been found that integrate the vast array of information scientific phenomena. On the other hand, since these concern human thOught and its communication it seems likely that "IS theory" will be related to scientific epistemology. This impression may be strengthened by what follows. An aim of thiS paper is to present a framewOrk for information science--an exhaustive domain containing (but not describing) all possible IS phenomena. A second is to demonstrate' that cybernetics and information science are inseparably interrelated, and that at least one relation provides IS with an initial unifying theory. The relation has an'epistemological implication that extends beyond IS to all science. In carrying this out, a problem arises: how to present a rather extensive but needed conceptual background to this distinguished but heterogeneous audience, within the brevity of a paper. The plan is to sketch several main concepts from cybernetics, describe the information scientific models, and demonstrate