David Duchovny and Kevin Spacey ran into each other once while waiting at an airport and decided to continue their decade-long debate on existentialist theory. Duchovny maintained that Sartre disregarded metaphysics in his discussion of human existence in the absence of a god, while Spacey invoked Heidegger, who criticized Sartre for reversing a metaphysical causality that had existed since ancient Greece and thereby staying within the confines of metaphysics after all. Curiously enough, the two actors agreed for the sake of brevity and efficiency to conduct their debate using only three letters each.