Abstract

As Alasdair Urquhart has noted, Bertrand Russell asserted that developing the theory of definite descriptions from 1905 was the first step towards solving the paradoxes that were finally resolved after 1908 in Principia Mathematica with the theory of types. I extend Urquhart’s suggestion that Russell was referring to the use of the notion of incomplete symbol in his solution to the paradoxes in his doomed theory “substitutional theory” of “Russellian propositions” in 1906. The Introduction to PM states that expressions for propositions are incomplete symbols. This paper assesses the status of propositions in PM and connects the theory of types with the theory of descriptions.