Then, they return to the larger group to report, expand, etc. Perhaps start class this way. But, be flexible. Notice where they are and how they might get to where you want them.
Students tend to be braver when offering seemingly objective answers.
Perhaps use e-journaling as a way to encourage students to reflect before class. Do NOT place yourself as the source of the discussion or the authority on the topic. Repeat the question. Rephrase the question. Resume the discussion, but perhaps in a distorted way.