This article presents a theoretical reflection on the post-foundationalism, a philosophical school that furthered the rising of French post-structuralism in the second half of the 20th century. It aims, particularly, to discuss the ontological, theoretical and epistemological implications of the post-foundational approach for researches in Social Sciences. To this end, first, the authors' understanding of what they call post-foundationalist Zeitgeist is discussed, especially the emphasis on the ontological difference and on foundation as Abgrund, according to Martin Heidegger's work. Second, the Heideggerian influence on Jacques Derrida's post-structuralist philosophical thought is presented. After that, the incorporation and use of Heideggerian ontology in the work of Ernesto Laclau is discussed, focusing on the notions of hegemony and populism. The article ends with considerations on the importance of post-foundationalism for social sciences researches.
Post-foundationalism; Post-structuralism; Abgrund; Ontology; Epistemology