You disagree while discussing, but (ideally) you agree in advance that there will be a) a mechanism for making a decision (e.g. voting, coin flipping) and b) th

You disagree while discussing, but (ideally) you agree in advance that there will be a) a mechanism for making a decision (e.g. voting, coin flipping) and b) there will be a commitment to work on the decided approach as if it were one's own. The opposite tends to result in endless discussions: people don't get to work in their full capacity - they still seek rebuttal, sneaking in their preferred approach, etc.