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.
You have a responsibility to be reasonable and considerate when you are advocating for your point of view and should never let your "lower-level you" gain control, even if the other person loses his or her temper. Their bad behavior doesn't justify yours.
If either party to a disagreement is too emotional to be logical, the conversation should be deferred. Pausing a few hours or even a few days in cases where decisions do not have to be made immediately is sometimes the best approach.