 Church’s (1943a) review of Carnap’s Introduction to Semantics (1942) constitutes an important early step in the application of the logistic method to the subject of semantics (see also Church 1943c, 1951b, 1952, 1956a). Like Frege, Church believed that the Sinn or sense of an expression is an objective—i.e., mind-and-language independent—abstract entity (cf.  §3.3  and  §6.3)  and that senses are needed in semantics for their power to explain the informative nature of identity statements containing co-designating names, as well as to explain the failure of the substitutivity of co-designating names in intensional contexts (1943a; 1956a: §01). Moreover, Church also shared Frege’s highly controversial view that in addition to assigning senses to expressions in scientific language, one should also assign them to expressions in natural language. (See  supplement E  for discussion.)