Does Heidegger Need Irony?

By way of Thomas Nagel's "The Absurd" an apparent lacuna is revealed in Martin Heidegger's existential system in Being and Time. Whilst there have been a plethora of interpretations giving content to Heidegger's notion of authenticity, there has been a critical lack of discussion on inauthenticity. Irony is presented as an answer to both this lacuna, and as a beginning to giving content to Heidegger's use of inauthenticity.