Persuasion Is a Cooperative Act, Not a Game

Don't treat arguments as a game where getting the other person to concede that you were right gives you points. If they say something that's irrelevant but true, pounce all over that and agree with it because then you're telling them that you're the sort of person who agrees with them. You also want to argue forwards, not backwards. A lot of times people get hung up in rearguing past arguments. And if you think we should ship the widgets, it is not important whether we should have shipped the widgets a month ago.