If you are wrong, it is good to lose the argument
We want to know the truth. The objective in an argument should not be to defeat the other person, but for the two sides to share knowledge so that one or both has a better understanding of what is true. While it may provide short term satisfaction to win an argument even if you are wrong, the long term result is that neither party has become any wiser.
Don't make it hard for yourself or the other person to change their opinion
Ego is usually involved when two people disagree. If our opinion is the correct one, the ideal result is that the other person ends up agreeing, not that the other person ends up humiliated. If we suggest that our opponent is a fool for disagreeing with us, he is likely to get angry and concentrate only on winning the argument, not on understanding the points we are trying to make. The opponent will resist agreeing even more strongly than before. If we turn out to be wrong after ridiculing our opponent, we then must either refuse to acknowledge the truth or suffer considerable embarrassment.
Expect opinions to change slowly
When debating an issue of some importance, each side usually has considerable prior experience on which their opinion is based. A good thinker should always spend some serious effort mulling over new arguments before he or she abandons opinions based on long experience. The new arguments could be faulty in ways we don't at first appreciate. It is important to be willing to reconsider our position, but we should not be hasty about it. We should also not be upset with others if they don't immediately accept some argument we have made.