*Critical Heuristics of Social Planning* has been recognised as the seminal work on critical systems thinking. Ulrich offers a new approach both to practical philosophy (which has until now remained rather unpractical) and to systems thinking (which has reduced the systems idea to a tool of merely instrumental, rather than practical, reason). *"Critical Heuristics"* will be recognised as a very important book in the emerging systems discipline and will hold a significant position for many years to come." (Peter B. Checkland, University of Lancaster, England) "An outstanding contribution to an adequate framework for critical social inquiry and design." (C. West Churchman, University of California, Berkeley, USA) "The book fills a major gap in the literature on the systems tradition." (Michael C. Jackson, University of Hull, England) "Drawing on a profound knowledge of both Anglo-American systems theory and German practical philosophy, this book belongs to the best studies I have seen on the normative foundations of planning and systems design." (Horst Steinmann, University of Erlangen-Nuremberg, Germany) "Mandatory for libraries in the field of planning." (John Friedmann, University of California, Los Angeles, USA)