Observations can only inform us of what happens, not why it happens.

In order to make statements about what "should" be, we must call upon faith, and not observation.

If you want to convince anyone that anything should be or do something, then appeal to their subjective sensibilities.

This manifests in moral / ethical / spiritual-based arguments, and is why politics is primarily mired in trying to unravel issues with no clearly measurable answer. If it was at all obvious that one side was right or wrong, then the discussion is over. It's only when it is not at all obvious which side is right that there is extended political discourse.

As such, anyone who asserts their side is unequivocally right is almost certainly not holding a well-informed position which considers all of the facts, without confirmation bias.