Full Idea
We ordinarily find no difficulty in saying of a given thing that several people believe it and so, if they think it false, 'make the same mistake' or 'labour under the same delusion'.
Gist of Idea
Several people can believe one thing, or make the same mistake, or share one delusion
Source
Gilbert Ryle (Are there propositions? [1930], IV)
Book Reference
Ryle,Gilbert: 'Collected Essays 2 1929-1968' [Routledge 2009], p.22
A Reaction
Ryle is playing devil's advocate, but this (like 13980) strikes me as quite good support for propositions. I suppose you can describe these phenomena as assent to sentences, but they might be very different sentences to express the same delusion.
Related Idea
Idea 13980 If you like judgments and reject propositions, what are the relata of incoherence in a judgment? [Ryle]