Propositions and Reasoning in Russell and Frege

Both Russell and Frege were inclined to think that there is nothing essentially linguistic about thought: any actual reliance of ours upon language is a mere psychological contingency. If so then it should be possible to formulate logic in such a way that logical relationships are not represented or expressed as principles pertaining to linguistic forms. Russell and Frege take pains to achieve this, but fail. I explain this by looking at some features of Grundgesetz and Principia . Their failure, I suggest, is due to the nature of the case.