The trope view allows the option of making mental causation compatible with the completeness of physical causation and exclusion by asserting that mental trope m is identical to physical trope p where that one trope falls into more than one class of tropes a mental type class and a physical type class p 141 2. Included in part 1 are an account of the universal particular distinction an argument for the existence of tropes based on the phenomenon of moving properties the development of a trope bundle theory of objects and a trope based solution to the problems of mental causations the second part presents a fuller picture of what a trope is by way of natural class trope nominalism according to which a tropes nature is determined by membership in natural classes of tropes in addition in . Ehring argues that trope theory can be used to show that mental properties have causal powers even in the face of the causal closure argument i find the discussion too brief to be conclusive but ehring does present an interesting case to the effect that causal powers associated with mental property types form subsets of the causal powers associated with physical property types assuming functionalism this enables ehring to identify mental property types with classes of tropes that belong . Properties and objects are everywhere we cannot take a step without walking into them we cannot construct a theory in science without referring to them given their ubiquitous character one might think that there would be a standard metaphysical account of properties and objects but they remain a philosophical mystery douglas ehring presents a defense of tropes properties and relations