I can't change your mind if I don't know what you're thinking.
Often we keep our ideas to ourselves so as to avoid this very scenario - having to debate and possibly have to backtrack or change an opinion.
When did respectful, spirited debate become a bad thing?
Mentors - engage your mentorees in debate. Don't just offer advice, ask your mentorees to challenge you. Challenge them. If we can't offer the arguments for our positions, do we really have an opinion?