From The Myths of Creativity By David Burkus
>> In the 1970s at Xerox PARC, regularly scheduled arguments were routine. The company that gave birth to the personal computer staged formal discussions designed to train their people on how to fight properly over ideas and not egos. PARC held weekly meetings they called "Dealer" (from a popular book of the time titled Beat the Dealer). Before each meeting, one person, known as "the dealer," was selected as the speaker. The speaker would present his idea and then try to defend it against a room of engineers and scientists determined to prove him wrong. Such debates helped improve products under development and sometimes resulted in wholly new ideas for future pursuit. The facilitators of the Dealer meetings were careful to make sure that only intellectual criticism of the merit of an idea received attention and consideration. Those in the audience or at the podium were never allowed to personally criticize their colleagues or bring their colleagues' character or personality into play. Bob Taylor, a former manager at PARC, said of their meetings, "If someone tried to push their personality rather than their argument, they'd find that it wouldn't work." Inside these debates, Taylor taught his people the difference between what he called Class 1 disagreements, in which neither party understood the other party's true position, and Class 2 disagreements, in which each side could articulate the other's stance. Class 1 disagreements were always discouraged, but Class 2 disagreements were allowed, as they often resulted in a higher quality of ideas. Taylor's model removed the personal friction from debates and taught individuals to use conflict as a means to find common, often higher, ground.
The main purposes of Dealer -- as invented and implemented by Bob Taylor -- were to deal with how to make things work and make progress without having a formal manager structure. The presentations and argumentation were a small part of a deal session (they did quite bother visiting Xeroids). It was quite rare for anything like a personal attack to happen (because people for the most part came into PARC having been blessed by everyone there -- another Taylor rule -- and already knowing how "to argue reasonably".