There lies the issue. Let's take the extremes: No two people share the same experience, therefore discussion is not possible, because one cannot share exactly

There lies the issue. Let's take the extremes: No two people share the same experience, therefore discussion is not possible, because one cannot share exactly the viewpoint of the other. That's the extreme on one end. On the other end, we can only take "rational facts" into account. In order to do this, we must discard completely all personal experience, which is first of all actually impossible between two human beings sharing a discussion, and second of all, will transform both participants into what amounts to deterministic computers who will arrive at precisely the same outcome given the same input. Now clearly if we are arriving at a shared conclusion between two people discussing a shared input, either extreme is impossible. Some nuance is required.