The conventional wisdom has it that between 1905 and 1919 Russell was critical to pragmatism. In particular, in two essays written in 1908–9, he sharply attacked the pragmatist theory of truth, emphasizing that truth is not relative to human practice. In fact, however, Russell was much more indebted to the pragmatists, in particular to William James, as usually believed. For example, he borrowed from James two key concepts of his new epistemology: sense-data, and the distinction between knowledge by acquaintance and knowledge by description.
Reasonable explanation of this is that, historically, Russell’s logical realism and James’s pragmatism have the same roots—the German philosopher Rudolph Hermann Lotze (1817–1881). In this paper we are going to explore the fact that in 1905, under Lotze’s influence, Russell married propositions with beliefs. A few years later this step also made Russell prone to embrace the theory of truth-making that has its roots in James.
In contrast to the concept of sense-data and to the distinction between knowledge by acquaintance and knowledge by description, however, the understanding that we believe propositions—and not, for example, simply grasp them—was in tension with Russell’s Principle of Extensionality, according to which propositions can be logically connected with other propositions only as truth-functions. The point is that when we judge a mind-relation (for example, a relation of belief) to a proposition, the latter cannot be determined as true or false.
The two most talented pupils of Russell, Wittgenstein and Ramsey, severely criticized the central place propositional attitudes play in Russell’s logic. Wittgenstein analyzed “A believes that p” to “ ‘p’ says p” (5.542). Ramsey criticized Russell’s beliefs in propositions the other way round: He stressed that belief is an ambiguous term that can be interpreted for the better in the sense of pragmatism. Prima facie surprisingly, he maintained that his “pragmatism is derived from Mr Russell.” (1927: 51)