 Definite descriptions are the logical constructions that Russell has in mind when when he describes them as “incomplete symbols”. The notion of a “logical fiction”, on the other hand, applies most straightforwardly to classes. Other constructions, such as the notions of the domain and range of a relation, and of one to one mappings that are crucial to the development of arithmetic, are only “incomplete” in an indirect sense due to their being defined as classes of a certain sort, which are in turn constructions.