When different opinions appear in the decision, the easy answer is to push the decision up. Let the boss decide.
There are two issues with this strategy. Firstly, while the boss will probably engage with the process, they will also hate it. They have enough to do without having to make decisions for warring teams. Plus, it never reflects well on those asking.
The bigger issue is when the team is in a matrix, and there is no obvious boss to pass the buck to. Then, the team has to find a way or risk the consequences of no (or late) decision!
In this episode of the podcast, Richard and Paul explore strategies that will help teams that disagree find solutions. From agreeing on where you agree to reciprocal behaviours, this podcast outlines strategies that you can use to create consensus and momentum.