Principles are ways of successfully dealing with reality to get what you want out of life.
Ray Dalio, one of the world’s most successful investors and entrepreneurs, cites principles as his key to success.
If both parties are peers, it's appropriate to argue. But if one person is clearly more knowledgeable than the other, it is preferable for the less knowledgeable person to approach the more knowledgeable one as a student and for the more knowledgeable one to act as a teacher. Doing this well requires you to understand the concept of believability. I define believable people as those who have repeatedly and successfully accomplished the thing in question--who have a strong track record with at least three successes--and have great explanations of their approach when probed.
If you have a different view than someone who is believable on the topic at hand--or at least more believable than you are (if, say, you are in a discussion with your doctor about your health)--you should make it clear that you are asking questions because you are seeking to understand their perspective. Conversely, if you are clearly the more believable person, you might politely remind the other of that and suggest that they ask you questions.
All these strategies come together in two practices that, if you seek to become radically open-minded, you must master.