  As mentioned in the previous paragraph, one way a theory of types might answer the question “what is a type?” is the way set theory answers the question “what is a set?” If types are universals, as most thinkers assume, then there are as many theories of types as there are theories of universals. Some axiomatic theories include Zalta 1983 and Jubien 1988. Since theories of universals are discussed at length in this Encyclopedia elsewhere, they will not be repeated here. (See   properties.)   However it might be said that types are not universals for the reasons mentioned in §3 above, where it was urged that types might be neither properties nor relations but objects, and there is an absolute difference between objects and properties. Identifying types as universals would appear to fly in the face of that consideration.