Trying to prove that we are right is the root of much of the disharmony we see around us. Arguments can make us feel angry and resentful. Instead, just say what you have to say calmly and let it go. Letting go isn't the mark of weakness. It's a sign of greatness and humility.
Agree to disagree. If you must argue, ensure the issue is important and your motives are correct. You're not out to prove you're right. You just want to discover the other person's point of view and share your own. Most of all, you want your relationship to be better off for having had the conversation, just like they do.