When you disagree with something, either you do it because you think your idea is better or you want to keep your ego intact. Let us ignore the latter and focus on the former where the intention is to let the best idea win. When a group of people sit down and try to resolve disagreements, many a time, it goes nowhere. Sometimes you get this strange feeling of things going around in a circle. This is due to whataboutery and shifting goal posts. You start with an objective, as the discussion progresses, statements lead to counter statements and at the end, no one knows what they are trying to resolve.
A straightforward hack to keep discussions on track is to write things down. Project a shared document where you note the objective and the point of contention. Whenever matters go awry, point people to the shared document; this helps everyone involved to stay focused and not to shift goal post as the discussion progresses.
Irrespective of how rational and mature one is, when someone disagrees with something that one believes to be true, one tends to become defensive and shift goal post without truly being aware of it. Writing things down makes one aware of this and helps course correct.