Russellian and Wittgensteinian Atomism

One difference between Russell's logical atomism in The Philosophy of Logical Atomism and Wittgenstein's in the Tractatus is that Russell's doctrine is explicitly epistemological, whereas Wittgenstein's is not; another difference is that Wittgenstein gives an a priori argument for the doctrine of logical atomism whereas Russell gives no such argument. I argue that these two differences are instructively connected: Russell's focus on epistemology prevents him from being able to give a motivated argument for the truth of logical atomism. Furthermore, I argue that this is not just a contingent failure of Russell's system: no primarily epistemological atomism can avail itself of Wittgenstein's style of a priori argument for the truth of atomism. An important suggestion of the argument, illuminating with respect to the subsequent history of analytic philosophy, is that Russell's logical atomism already contains the seeds of verificationism in a nascent form, whereas Wittgenstein's atomism has no tendency toward verification.