Deliberative democracy depends on speech being referential, ie the speaker's words are referents to objects and concepts that meaningfully exist beyond the speaker. The words represent the speaker's thoughts and interests with respect to those.
But in practice speech is often instrumental: Ppl decide what to say in order to get what they want, based on the social effect they believe it will have.
cf Matt Bruenig https://mattbruenig.com/2022/12/30/the-contradictions-of-deliberative-democracy/