Christophe Bouriau is a professor at the University of Lorraine and a member of the Poincaré Archives (UMR 7117). With Charles Braverman, he directs the collection “Philosophie allemande : une autre histoire”, published by the Presses universitaires de Lorraine. A specialist in German philosophy, he has translated into French the Philosophy of the As-If of the Neo-Kantian Hans Vaihinger (1852-1933), and has devoted a book to Vaihinger’s invention of “fictionalism,” a philosophical trend that is very much alive today in the debates between “realists” and “fictionalists” on various subjects. The title of this work is: The as if. Kant, Vaihinger et le fictionalisme (Cerf, 2013). Christophe Bouriau has also devoted several works to Hans Kelsen, a great reader of Vaihinger, highlighting the fruitfulness of his theory of legal fictions. In this perspective, he is currently translating in collaboration with Carlos Herrera : Hans Kelsen, The Sociological Concept and the Legal Concept of State. A Critical Inquiry into the Relationship between the State and Law (1922). His reflections focus on the fictions of environmental law: is it legitimate to consider certain natural areas as legal persons, to act “as if” “things” were “persons”?