In May 1984 the Swedish Council for Scientific Research convened a small group of investigators at the scientific research station at Abisko, Sweden, for the purpose of examining various conceptual and mathematical views of the evolution of complex systems. The stated theme of the meeting was deliberately kept vague, with only the purpose of discussing alternative mathematically based approaches to the modeling of evolving processes being given as a guideline to the participants. In order to limit the scope to some degree, it was decided to emphasize living rather than nonliving processes and to invite participants from a range of disciplinary specialities spanning the spectrum from pure and applied mathematics to geography and analytic philosophy. The results of the meeting were quite extraordinary; while there was no intent to focus the papers and discussion into predefined channels, an immediate self-organizing effect took place and the deliberations quickly oriented themselves into three main streams: conceptual and formal structures for characterizing sys tem complexity; evolutionary processes in biology and ecology; the emergence of complexity through evolution in natural lan guages. The chapters presented in this volume are not the proceed ings of the meeting. Following the meeting, the organizers felt that the ideas and spirit of the gathering should be preserved in some written form, so the participants were each requested to produce a chapter, explicating the views they presented at Abisko, written specifically for this volume. The results of this exercise form the volume you hold in your hand."

The chapters in this book centre around one main theme, the concept of the machine and its use as metaphor in a variety of contexts. This concept is deeply rooted in western culture and is frequently used to interpret complex systems in nature and society. With the advent of electronic computers, the machine metaphor applied to thinking and the brain has becOIne even more pertinent. The idea of a machine has changed over time. In this book these transformations are made trans parent, various aspects of the machine metaphor are discussed and limitations and pitfalls of the metaphor are elaborated. The chapters are written in a non-technical fashion and are accessible to a large readership of scientists and also laymen interested in the scientific per spectives and logical foundations of the machine concept that has been so influential in western thinking. The idea of the book has its origin in a workshop held at the Sci entific Station in Abisko, Sweden, in May 1990, where several of the present authors participated. The meeting was organized and spon sored by the Swedish Council for Planning and Coordination of Re search (FRN). Since 1983, the FRN has actively promoted a series of such annual events at Abisko, all of which have been devoted to the exploration of various aspects of complex systems and their evolution.