### Abstract

It is known since Plato that, in order to remain metaphysically consistent, one cannot simply equate a
thing with the collection of its properties, i.e., count its being among the predicates applicable to it (Kant
agreed with him in this respect). Transcendental idealism (Kant, Cassirer, Husserl) thus continued the
disentanglement of the concepts "structure" and "substance". Nevertheless, many of the debates concerning
identity do take - following Leibniz - at least their aequivalence as a starting point. The consistency
problem thus hurts logical, philosophical, mathematical, and even physical (in quantum mechanics) positions
concerning identity. This has been reckoned not only by recent work in philosophy of science (Castellani,
French) but also in strands of what is so unaptly called "continental philosophy" (from Heidegger to Deleuze).
Alain Badiou’s philosophical work is among the very rare to bring together the insights obtained in these
different traditions, by means of his ideas on a dynamical and pluralistic ontologie transitoire. During
this workshop different ways to approach the according to some (Lewis) straightforward, but notoriously
recalcitrant metaphysical concept of "identity" will be presented and discussed.
Contributions will not focus too much on specific notions of identity, but develop a proper point of view
on identity as such, although examples can of course be dealt with. We want to highlight nevertheless one
important point: the debates on whole-part relationships, stability and change, subsistency through time
and the like all start implicitly or explicitly from the idea that objects precede properties, ontologically.
Recent developments in mathematics (category theory) open up roads to a formal treatment of a more
"structural" viewpoint. How to do justice to this new possibility, while at the same time reckoning the
consistency-problem identified (!) by Plato? Some might see this as again another reason to change our
point of view, not only on identitly, but on consistency as well. The workshop invites philosophers, mathematicians
and logicians to participate in an exchange of ideas that aims at excavating the foundations of this
subject-matter. The point is less to reach a common view than to enhance deep understanding of what is
at stake. Contributions from philosophers (ontology, metaphysics...), logicians (universal logic, paraconsistency...),
mathematics (set and category theory), computer and natural scientists are particularly welcomed.

**-- Dr. Karin Verelst**