"Do not think! Do not repond!"
You see, your own words will only add fuel to the arguing machine in front of you. They will be twisted to their own benefit. Each reply you give will offer them a new opportunity to contradict you. If you stop adding fuel... the machine runs out of gas and stops. Really! (It might take some time.)
But you need to say something right... you can't just stand their like a lump. Try simple repeating the same phrase over and over as they try to engae you more. Some people say, "I love you to much to argue." One teacher chose, "I only argue after 3:30 m daily. "
If their arguing and manipulation techniques stop working on you... eventually they will stop trying to use them because they realize it won't get them what they want.
Beware of your own competitve instinct though. This is not about one-upmanship or "winning." Healthy, direct communication without manipulation is the goal. There's more on this in the book: Love and Logic Magic When Kids Leave you Speechless" from http://www.loveandlogic.com/