If your opponent is an important person – bring a gift and it will be easy to get an appointment.
If your opponent is the first person to speak – it will seem like they are right to the listening audience. Be patient, your turn will come to question them and the matter will be clearer. Even if convinced that your opponent is utterly wrong, yield gracefully, decline further discussion, or dextrously turn the conversation, but do not obstinately defend your own opinion until you become angry, or more excited than is becoming to a gentleman.
If you and your opponent are of equal strength and find yourself facing each other as friends, maybe this is the time to flip a coin to settle the issue.