"What would it take to change your mind?" is either a starter for bribery, or it at least implies that the mind of the other needs changing. All your "rational discussion" stuff aside, please explain to me what exactly about this you are not understanding? I might add that it also does not help a rational discussion if one part is lacking the ability to empathize with the other, and tries to invalidate the other by claiming their whole point is invalid, without even trying to zoom in on it.