In my previous post I talked about what to do when presented with a question of priorities. I argue that the answer is to do "both". But what about when those two priorities are mutually exclusive? "Do we make the button green or orange?" You can't really do both in this case, right?
When two people disagree on a choice like this, it often means there's a fundamental difference in understanding of the topic itself. Maybe they 'weigh' the priorities differently. In the example of "green" vs. "orange", maybe they're really arguing "positive" vs. "bright".
The first step in any disagreement is to get people talking it through. With luck, they can work it out just by sharing their own understandings of the subject. But fairly often the opinions will be strongly held, and difficult to change. So then what?
The answer is exactly the same as the question priorities: Do them both.
In this case, it's not a question of difficulty, but of cost. Doing them both costs twice as much, but often will lead to a better overall solution. This is the same idea behind A/B testing where you put both options out there and let the data decide.
Even for simpler things, where 'common sense' dictates one is probably better than the other, data (or customer feedback) can often reveal completely different understandings.
And beyond ending up with a better solution, this is another way to get arguing team members to compromise and work together, which is almost always more valuable than getting a button color just right.