They don’t have a definition of deliberation, but they do define human deliberative reasoning as the ability to build and organize collective reasons that consistently support people’s preferences. They use this to test how well LLMs reason deliberatively compared to human participants.

They compare 54 LLMs to 526 human responses across 24 deliberation cases. Their preliminary findings are that humans outperform LLMs in most deliberation cases, but some LLMs perform on par with humans.