4.0031 All philosophy is “critique of language.” (Though not in Mauthner’s sense.) Russell’s merit is to have shown that the apparent logical form of a proposition need not be its true form.
So Russell’s philosophy is not all nonsense, but perhaps most of it is, especially if this is the only idea of merit in Russell’s work.
Separate point: and yet, see 5.5563. Any apparent inconsistency between these two remarks is, I think, cleared up by the reference here to Russell’s point.
Mauthner was skeptical about the ability of language to convey truth because, he thought, it only pictures reality, never actually coinciding with nature. See Nordmann pp. 117-121. For Mauthner, language is conventional and based on metaphor, so it can never really grasp the real world. See Stokhof pp. 25-27.