I respectfully disagree with your comments re: third opinions.
Often the best way to 'win' an argument in a group context is to derail the current thread of conversation (in which both sides have their arguments clearly in mind) and change the term of the debate in a way that suit you. This will have the effect of throwing off would-be adversaries (by the time they have their shit together to counter your new argument, the conversation is long gone) and gaining followers of your new idea.
Often the best way to 'win' an argument in a group context is to derail the current thread of conversation (in which both sides have their arguments clearly in mind) and change the term of the debate in a way that suit you. This will have the effect of throwing off would-be adversaries (by the time they have their shit together to counter your new argument, the conversation is long gone) and gaining followers of your new idea.