  In their early writings, Russell and Moore endorse propositionalism. In his 1903 book The Principles of Mathematics, Russell affirms the existence of propositions, taking them to be complexes of ordinary concrete objects (the referents of words) rather than of Fregean senses (p. 47). Propositions so conceived are now standardly called Russellian, and propositions conceived as complexes of senses or abstract entities are called Fregean. In his 1899 paper, “The Nature of Judgment,” Moore affirms the existence of propositions, taking them to be broadly Fregean in nature (in particular as being complexes of mind-independent Platonic universals which he calls concepts).