After 1905, we see in Russell a parsimonious inclination. He wants to eliminate entities from his ontology. Some time between 1908 and 1910 he begins to deny the existence of propositions and this denial continues until he develops a theory of propositions as structures of images or words in (1918). What, then, is the fate of propositional functions? It might seem difficult to understand what a propositional function is without the existence of propositions, but Russell's view is, not that complicated.  Russell only rejects false propositions. He retains facts in his ontology. Propositional functions, in Principia, are what we now call ‘partial functions’. That is to say, they do not always have values. For example, the propositional function __ is a dog does not have a value for the Sydney Opera House taken as an argument, but it does have a value when my dog is taken as its argument. So, the rejection of false propositions does not cause a serious problem for the theory of propositional functions in Russell.