Partner, Contentious Character
It needs to be a ‘how’ question around:
How did you arrive at the conclusion which you are currently putting forward?
How did you arrive at the position that you are currently putting forward?
How did you arrive at that?
This encourages people to think about their process and their rationale and whether or not they are bringing their personality into the process and for better or for worse.
This also then gives you some understanding of the position being proposed and how they got there and may in fact alter your next step as a result of that.
It becomes a two-way interaction where both people are continuing to open up and expose the relevant information that will bring greater understanding and hopefully a better position out of the discussion.