Full Idea
When Russell moved to his multiple relation theory of judgement …he then faced difficulties making sense of the unity of sentences.
Gist of Idea
The multiple relation theory of judgement couldn't explain the unity of sentences
Source
comment on B Russell/AN Whitehead (Principia Mathematica [1913], p.44) by Michael Morris - Guidebook to Wittgenstein's Tractatus 3A
Book Reference
Morris,Michael: 'Guidebook to Wittgenstein's Tractatus' [Routledge 2008], p.117
A Reaction
Roughly, he seems committed to saying that there is only unity if you think there is unity; there is no unity in a sentence prior to the act of judgement.