The birth of analytic philosophy was based on the arguments G. E.
Moore and B. Russell set against idealism.
First, I shall explain how the notion of proposition as transcendent unity came from the criticism. Moore and Russell criticized Kant's/Bradley's abstractionism, which led them to refute the principle of analytic unity of apperception and its correlate, the synthetic unity.
Subjective unity of judgment was replaced by objective unity of proposition. This specific conflict between realism and idealism, nonetheless, cannot be merely a conflict of doctrines; I state that the conflict was primarily based on some normative assumptions, which leads us from questions after what is true to a project of revealing the values and ideals which a particular set of doctrines is supposed to affirm.
The second part of the study is devoted to an explanation of the reasons which made Russell, during 1905 and 1910, to change profoundly his defence of realism. Naïve realism embraces decisively the ethos of reality's transparency to cognitive agents; it fails, however, when used to analyse the notions of truth and knowledge.
There was also the Theory of descriptions which eventually played an important role in Russell's doubts about naïve realism. As I shall show, the theory was not compatible with realism of propositions.
It was so since the refutation of non-existents must have meant also the refutation of objective falsehoods, which, in turn, must have led to a radical revision of the notions of proposition and judgment. Russell should have come this way to the epistemological basis of his later logical atomism - and he did until he confused his position by accepting the ontology of positive and negative facts around 1918.
The Theory of description did not play only motivational role with regard to the abandonment of realism of propositions but also a constitutional role as we shall see in the interpretation of the thesis that propositions are incomplete symbols.