Be calm in arguing; for fierceness makes error a fault, and truth discourtesy.

Heat changes how what you say lands. Argue fiercely and a small mistake stops looking like a mistake and starts looking like bad character, while the part you have right arrives as an attack, so no one can accept it without feeling beaten. Your temperature, more than your evidence, decides whether the other person can hear you at all.

Next time you feel the pitch of a disagreement rise, slow your sentences down before you sharpen them. Ask a question you do not already know the answer to. Nothing you were actually right about gets lost that way.