I think rather than a single person, you want exactly two people who have to agree on something to make a decision; and if you can't get to a decision, it's pro

I think rather than a single person, you want exactly two people who have to agree on something to make a decision; and if you can't get to a decision, it's probably a sign you need to solve other problems first. That way, there's someone who can challenge your opinion and you have to convince them to agree with it or find an alternative. Often during the convincing part you identify issues that you wouldn't have thought of by yourself, and since you don't have ultimate authority by yourself, you're less likely to unintentionally shut up someone who wants to disagree but defers to authority.