These people are having a heated discussion, which means that emotions, rather than reason, has taken the driver's seat. They need to take a "time out" and try to discuss the issue calmly.
These Rules of Polite Discourse were developed as guidelines for "fair fighting" and conflict resolution in person but most also apply to online forum and Wikipedia discussions as well.
Address issues promptly – If you let feelings fester, that is just what will happen: They will rot you from the inside out.
Express your feelings and thoughts – How can you expect the other person to understand if you don't express yourself completely?
Listen actively – Active listening involves eye contact, nods, and affirmations. Listen both for what is said and what is not said, for feelings expressed and feelings suppressed.
Don't get upset – Allowing yourself to become driven by emotion indicates that your reason has taken a back seat. If you notice yourself or the other person becoming agitated, call a "Time Out."
Validate the other person – Each person's feelings and concerns are important, however misguided they may seem. Realize that other people's perspectives ARE their reality, the way they honestly see the world.
Don't get defensive – If you notice yourself becoming defensive, say so or ask for a "Time Out." If you sense the other person becoming defensive, try to ease the tension and examine what could have triggered such a response.
Avoid "You always ..." generalizations – Accusatory statements usually trigger defensive behavior and do not promote free expression. Try to use specific examples – "always" and "never" statements are weak, needing only one exception to be disproved.
Stay on topic – Do not allow other issues to enter into the discussion. Though important, these issues deserve to be addressed separately.
Check understanding – Try restating what you heard to see if that was the intended message. It takes two to communicate – the speaker AND the listener. Both parties share the responsibility for clear communication.
Don't be repetitive – If you repeat a statement to clarify a misunderstanding, be sure to emphasize the difference in meaning – otherwise you may seem to be merely grandstanding.
Always be respectful – Rudeness is never appropriate or acceptable. Remember that to earn respect you must first show respect for others.
Don't interrupt – No one likes to have a train of thought derailed by an impatient listener. What you have to say is very important, but listening to the other person is even more important. Frequent interruptions indicate a lack of concern for what the other person has to say.
Let the other person respond – If you launch into a tirade, listing a multitude of offenses, you are inviting an interruption. The other person surely has a response for each of your statements and, denied the opportunity to express these thoughts, will rapidly become impatient or agitated.
Suggest solutions – It is easy to complain about a problem. Actually suggesting solutions requires much more time, effort, and thought. The very act of developing a solution requires viewing the problem from a new perspective and, possibly, realizing how difficult it is to design and implement a workable solution.
Agree to disagree – Sometimes a solution cannot be found. In such cases, agree that you will not resolve the issue during this session and end the discussion on good terms.