Avoid Arguments Section of "How To Win Friends And Influence People".

(If you're a Ford salesman) When someone says, "What? Ford's cars are no good! I wouldn't take one if you gave it to me. I'm going to get Chevrolet cars." Say, "Brother, listen, Chevrolet's cars are good cars. Their cars are made by a fine company and sold by good people." He's speechless then. There's no room for an argument. If he says Chevrolet's cars are the best and I say sure it is, he has to stop. Just agree with him. He can't go on all afternoon when I'm agreeing with him. We then get off the subject of Chevrolet's cars and I begin to talk about the good points of Ford's cars.

Dale Carnegie on Amazon