The Gaia hypothesis (GH) has been proposed by Lovelock and Margulis in the 1970’s. It has long been caricatured as a folkloric or pseudo-scientific hypothesis which was of interest to nobody but to the New Agers. This standard account emerged in the wake of criticisms formulated by evolutionary biologists in the early 1980’s. Yet it does not correspond to GH’s real historical trajectory. This standard account is problematic for two reasons: it obliterates the deep influence that GH had on the sciences of the Earth and the environment through the constitution of the “Earth system science(s)”; it prevents one from seeing the political stakes that GH harbors, and in particular the complex relationships that Lovelock and GH have long entertained with political ecology at large.
I will first put into question the standard account through a historical analysis of GH’s elaboration and rich reception in various disciplines (evolutionary biology, climatology, ecosystem ecology, biogeochemistry), and through a philosophical analysis of the uses of demarcation criteria between science and pseudo-science. I will then show that GH’s major scientific controversy does not bear on theoretical issues dealing with GH’s relationships with natural selection and evolutionary biology, but rather results from the massive ambiguity on GH’s status (is it a hypothesis? A theory? A research program? A philosophy of nature?) and from the concrete political prescriptions Lovelock derived from GH. Finally, through a historical analysis of the Earth system science(s)’ constitution and development since the 1980’s, I will shed light on the various ways through which GH had deeply and durably influenced the sciences of the Earth and the environment.