In the article the ontological context of the modern phenomenon of understanding philosophy as activity is studied. A number of approaches based on the similar interpretation of philosophy are considered. Special attention is paid to the analysis of the conception of philosophy as “criticism of language” presented in L. Wittgenstein’s “Tractatus Logico-Philosophicus”. The author identifies the main features of such ontology, which makes the interpretation of philosophy as activity not only possible but necessary. As the most important categories of this ontology the notions “Event” and “border” are singled out.