This article proposes to confront the tenets of metaphysical detective fiction, a sub-genre of experimental fiction associated with Postmodernism, with Chesterton’s Father Brown series, with which the genre of metaphysical detective fiction was first identified. The expression was originally coined by the American critic Howard Haycraft to single out Chesterton’s unusual detective stories, but since Michael Holquist’s founding article “Whodunit and Other Questions: Meta-physical Detective Stories in Post-War Fiction,” it has come to describe the postmodernist take on detective fiction, in the works of authors like Jorge Luis Borges, Vladimir Nabokov or Alain Robbe-Grillet. However, Holquist does not acknowledge Chesterton’s defining role in the birth of the genre and falls short of a precise definition for its “metaphysical” quality. Such “dual” discomfort is equally palpable in most studies of the genre. Significantly, they have ignored Borges’s role as a mediator between Chesterton and contemporary metaphysical detective fiction. Through a survey of the “Father-Brownian” intertextuality in some of Borges’s Fictions, this paper aims to examine the “metaphysical” quality of Father Brown stories, in order to account for the recurring critical unease in defining Chesterton’s role as an innovator of the genre.