Dispositional monism, relational constitution and quiddities
Let us call dispositional monism (DM) the view that all natural properties have their identities fixed purely by their dispositional features, that is, by the patterns of stimulus and response in which they participate. DM implies that natural properties are pure powers: things whose natures are fully identified by their roles in determining the potentialities of events to cause or be caused. As pure powers, properties are meant to lack quiddities in Black's (2000) sense. A property possesses a quiddity just in case its identity is fixed by something independent of the causal-nomological roles it may enter into. Paradigmatically, a categorical property is thought of as a property whose identity is fixed by a quiddity (Bird 2006; Black 2000; Mumford 2004).