Abstract:
This thesis seeks to elucidate a motif common to the work both of Jean-Paul Sartre and Alain Badiou
(with special attention being given to Being and Nothingness and Being and Event respectively): the
thesis that the subject 's existence precedes and determines its essence. To this end, the author aims to
explicate the structural invariances, common to both philosophies, that allow this thesis to take shape.
Their explication requires the construction of an overarching conceptual framework within which it
may be possible to embed both the phenomenological ontology elaborated in Being and Event and the
mathematical ontology outlined in Being and Event. Within this framework, whose axial concept is that
of multiplicity, the precedence of essence by existence becomes intelligible in terms of a priority of
extensional over intensional determination. A series of familiar existentialist concepts are reconstructed
on this basis, such as lack and value, and these are set to work in the task of fleshing out the more or
less skeletal theory of the subject presented in Being and Event.
