an anti-foundationalist is one who does not believe that there is some fundamental belief or principle which is the basic ground or foundation of inquiry and knowledge…
The definition, from Wikipedia, continues: “Anti-foundationalists use logical or historical/genealogical attacks on foundational concepts (see especially Nietzsche and Foucault), often coupled with alternative methods for justifying and forwarding intellectual inquiry, such as the pragmatic subordination of knowledge to practical action.”