The Living and Its Milieu

The notion of milieu is in the process of becoming a universal and obligatory means of registering the experience and existence of living things, and one could almost speak of its constitution as a basic category of contemporary thought.' But until now, the historical stages of the formation of the concept, its diverse uses, as well as the successive reconfigurations of the relationships in which it takes part, whether in geography, biology, psychology, technology, or social and economic history, all make it rather difficult to make out a coherent whole. For this reason philosophy must, here, initiate a synoptic study of the meaning and value of the concept. By "initiate" I do not simply mean the pretense of an initiative that would consist in taking a series of scientific investigations for reality and then confronting expectations with results. Rather, it is a question of using several approaches and engaging them in a critical confrontation with each other to locate, if possible, their common point of departure and to explore its potential richness for a philosophy of nature that focuses on the problem of individuality. It is therefore appropriate to examine the simultaneous and successive elements of the notion of milieu each in turn, the various usages of this notion from 1800 to the present, the many inversions of the relationship between organism and milieu, and finally the general philosophical impact of these inversions. Historically considered, the notion and the term "milieu" are imported from mechanics to biology in the second half of the eighteenth century. The mechanical idea, but not the term, appears with Newton, and the word "milieu" is present in d'Alembert and Diderot's Encyclopedia with its mechanical meaning, in the article of the same name. It is introduced to biology by Lamarck, who was himself inspired by Buffon, though he never used the term other than in the plural. De Blainville seals this usage. Etienne Geoffroy Saint-Hilaire in 1831 and Comte in 1838 use the term in the singular, in an abstract sense. Balzac opens the gates to literature in 1842, in the preface of the Comrdie Humaine, and it is Taine who first uses it as one of the three analytical principles used to explain history, the two others being race and event, as is well known. It is more due to Taine than Lamarck himself that neoLamarckian biologists in post-1870 France, such as Giard, Le Dantec, Houssay, Costantin, Gaston Bonnier, and Roule, use this term. They get the idea, in a sense, from Lamarck, but the