The ministry of the environment has for many years financed studies and reflections concerning problems of competence in centers of independent research. Certain pursuits, however, by virtue of their high quality, merit publicization. This book collects 31 contributions from sociologists, legal experts, economists, and philosophers. These contributions are grouped around three themes. The first is that of the representation of the environment as an issue of the management of land. The second theme is that of activism: various associations, ONG, pressure groups, ecological movements, etc. The third is that of major risks to the environment: nuclear power, prions, the greenhouse effect, etc. All of these reflections point to two major motifs: that of a durable association between economy and ecology, and that of the principle of precaution necessary in and for future generations.