Do some objects have essential properties—properties that they could not lack and which play some role in characterizing their nature? Essences play a starring role in recent debates about metaphysical modality and methodology. In current work, I investigate potential anti-essentialist arguments. I am also interested in the best approaches to modal conventionalism—in particular, the view that modal truths depend on explanatory conventions. I am weighing the costs and benefits of conventionalist theories of essences. Even more generally, I am interested in the metaphysical implications of modal logic, the metaphysical commitments of possible-worlds semantics, and versions of modal logic that do not take operators as structural. And in my Time Biases book I consider when and why it is rationally permissible to form preferences over metaphysical impossibilities.