First, by giving a historical overview, I show how the last fifty years of Borgesian criticism mostly reveals contradictions and misunderstandings when the meaning of philosophy and metaphysics in Borges?s works is studied. Second, through a semantic analysis of the words philosophy and metaphysics, even in Borges?s correspondence and some of his early essays, I argue that philosophical doctrines differently deploy in the historical development of Borges?s opus, not only in the form of irony?as countless critics have always affirmed?, but also and most fundamentally in the form of inspiration, positive and negative experimentation, or radicalization. Third, literary theory and the history of ideas help me to propose a new understanding of the word fiction in Borges?s works. I found that this Borgesian word, still at stake in contemporary critical discussions of Hispanism (I think of Saer and Piglia, for instance), has unexpected roots in and profound debts to philosophers such as Kant, Nietzsche, and Vaihinger. Forth, I show how French critical thinking in the second half of the 20th century finds in Borges one of its most seductive sources of inspiration. Particularly, Borges?s essays and short stories are catalyzers for that kind of thinking. Authors such as Blanchot, De Man, Genette, and Foucault philosophize with Borges in topics touching the death of the author, the anonymous presence of artistic works, the inter-textual threads of any writing, the suspicion towards all discourse pretending to be mimetically realistic, and even the Borgesian way of destabilizing absolute, human categories used to classified things in the universe. Fifth, and as a counterpoint with other related theories (Plato, Aristotle, Cicero, Agamben), I give new ethical and political light to Borges?s literature studying some of his texts through underlining what Borges used to call a very Argentine passion, that is, friendship. If I am right, because his literature has a strong praise of friendship, Borges?s works can be no longer understood as intellectually solipsistic. In the conclusion of my study, a thought-provoking analogy offers a way to provisionally understand the way philosophy and literature are related to each other in Borges?s opus.