Most people are excellent sceptics when evaluating the opposing tribe.
Their sources are biased. Their statistics are cherry-picked. Their emotional anecdotes prove nothing. Their leaders have incentives. Their experts can be wrong.
Then our side speaks and suddenly the audit log goes missing.
Symmetry is a useful diagnostic
You do not have to believe both sides are equally correct. They usually are not. The useful discipline is applying the same test before deciding that.
If an anonymous source is unacceptable when it hurts your side, it should not become sufficient when it helps.
If one person’s criminal behaviour does not represent an entire group you like, it should not represent a group you dislike.
If conflicts of interest matter, they matter for allies too.
The goal is not neutrality
Neutrality can become another performance. Sometimes the evidence strongly supports one conclusion.
The goal is a process that can reach an inconvenient answer.
A belief system that only confirms what you already wanted is not a method for discovering truth. It is a customer-service department for identity.