It reveals the perplexities of truth and falsity of judgments and propositions, demonstrating a connection with possibility and necessity.

Responding to Russell is a constant throughout Wittgenstein's philosophizing. This Element focuses on Wittgenstein's criticisms of Russell's theories of judgment in the summer of 1913. Wittgenstein's response to these criticisms is of first-rate importance for his early philosophical development, setting the path to the conceptions of proposition and of logic in Tractatus Logico-Philosophicus. This Element also touches on further aspects of Wittgenstein's responses to Russell: the rejection of Russell's and Frege's logicisms in the Tractatus, the critique of Russell's causal-behavioristic philosophy of mind in Wittgenstein's 'middle' period, the Russellian origins of notions of privacy dialectically treated in Philosophical Investigations, and the discussion of 'surveyability' of mathematical proof in Remarks on the Foundations of Mathematics, which is, again, a response to Russellian logicism.