Do you have friends that you can say are genuinely open-minded? Yes? Then you are very lucky; nurture their friendship. In my experience such people are rare. Most people will come to a discussion with fixed ideas and opinions that seem to be etched on tablets of stone handed to them on Mount Sinai.
But what exactly do I mean by open-minded? Well - an open-minded person will often have a view on a particular issue but they will regard their view as their current view; it is provisional and subject to modification or revision. If you suggest another angle and they agree, they will say so. Of course, this must also apply to yourself mutatis mutandis. Such a discussion is not adversarial as in English Law, but investigative as in French Law. For all parties, the discussion is a joint building exercise; the objective is the truth or, more accurately, as close as you can get to the truth.
Knowledge, intelligence and analytical ability are all 'good to haves' but I suggest that the essential quality is Open-mindedness.