 There is a domestic dispute among supporters of properties in the metaphysics of science, regarding the very nature of such properties (or at least the fundamental ones). We may distinguish two extreme views, pure dispositionalism and pure categoricalism. According to the former, all properties are essentially dispositional (“dispositional”, for brevity’s sake, from now on), since they are nothing more than causal powers; their causative roles, i.e., which effects their instantiations can cause, exhaust their essences. According to pure categoricalism, all properties are essentially categorical (in brief, “categorical”, in the following), because their causative roles are not essential to them. If anything is essential to a property, it is rather a non-dispositional and intrinsic aspect called “quiddity” (after Armstrong 1989), which need not be seen as an additional entity over and above the property itself (Locke 2012, in response to Hawthorne 2001). Between such views there lie a number of intermediate positions.