If I am arguing with someone and I change my mind as a result of the argument, I consider myself to have "won" because I gained knowledge.

If we accept all beliefs as provisional and only look to the argument as a method of hypothesis testing, it can be part of a group's rational process.

However in my opinion the best way to approach group decision making is to acknowledge that all decisions have tradeoffs and then evaluate various ideas based on their relative tradeoffs.

Teams with a bullying culture find the tradeoff matrix annoying because it deflates the intimidation tactics that some members use to get their way and shut other people down. For an example just bring up Mongodb.