Full Idea
It is argued by Husserl and (virtually) by Meinong that only if there are such entities as objective Meanings - and propositions are just a species of Meaning - is there anything for Logic to be about.
Gist of Idea
Husserl and Meinong wanted objective Meanings and Propositions, as subject-matter for Logic
Source
Gilbert Ryle (Are there propositions? [1930], IV)
Book Reference
Ryle,Gilbert: 'Collected Essays 2 1929-1968' [Routledge 2009], p.21
A Reaction
It is presumably this proposal which led to the scepticism about meanings in Wittgenstein, Quine and Kripke. The modern view, which strikes me as right, is that logic is about inference, and so doesn't need a subject-matter.