  By the time Moore returned to Cambridge in 1911 to a lectureship there, Russell  and Whitehead were finishing off their massive project of exhibiting the logical foundations of mathematics — Principia Mathematica. Although Moore was neither a mathematician nor a logical theorist he was one of the first people to grasp that Russell's new logical theory was an essential tool for philosophy and offered important new insights. One example of this concerns the status of propositions, the ‘objects’ of thought. As we saw above, in his early work Moore had been emphatic that propositions are altogether independent of thought and had even proposed that facts are just true propositions. But as he came to think more about falsehood in his lectures Some Main Problems of Philosophy of 1910–11, it became clear to him that this position was a mistake, since the truth of a proposition should not affect its  ontological status and yet it would be absurd to give false propositions the status of facts. So he now rejected the view that facts are just true propositions. On his new view, facts are, as before, constituted by objects and their properties; but what about propositions? According to Moore, philosophers talk legitimately of propositions in order to identify the aspects of thought and language which are crucial to questions of truth and inference, and in doing so it may appear that they regard propositions as genuine entities. But, Moore now holds, this implication is unwarranted: the mistake here is one of supposing that ‘every expression which seems to be a name of something must be so in fact’ (Some Main Problems of Philosophy, 266). Moore does not allude here explicitly to Russell's theory of incomplete symbols and logical fictions, but it is clear that this is the kind of position he has in mind. The new logic enables one to preserve realist appearances without accepting realist metaphysics.