Abstract
"Philosophical knowledge and knowledge of essences": the title of this symposium could just as well be the title of a book on the work of the philosopher Christian Wolff (1679-1754). This should come as no surprise, given the structuring role it played in the development of a metaphysics linked to modern science, and in the constitution of the German philosophical language. Starting with a paragraph from Discursus praeliminaris, we will show how the question of the "authentic form of propositions" appears and is constituted in Wolff's thought. This will enable us to analyze the characteristics of Wolff's doctrine of essence, and determine how it operates both theoretically and practically. We will then be able to show how Wolffian thought opens up the field of inquiry of the metaphysics of modern science, by setting up a series of conceptual elaborations that are generally conceived from, and reduced to, their Kantian reprise: the question of the articulation of logic, psychology and ontology; the opposition and articulation ofa priori anda posteriori ; the meaning of the notion of possibility.
