 Anselm, Saint [Anselm of Bec, Anselm of Canterbury] |  a priori justification and knowledge |  Berkeley, George |  Descartes, René: modal metaphysics |  essential vs. accidental properties |  experimental philosophy |  grounding, metaphysical |  Husserl, Edmund |  imagination |  intuition |  Locke, John: on real essence |  logic: modal |  modality: medieval theories of |  Platonism: in the philosophy of mathematics |  possible worlds |  rigid designators |  semantics: two-dimensional |  zombies 