The life changing magic of tying out numbers, or how to get to trustworthy data from first principles.
I would say that truth is really just a form of consensus - "you agree and I agree and she agrees so we're all agreed". If two metrics fail to reconcile, it's the same as a lack of consensus. And often we have to achieve consensus across many things (this system, that system, their intuition, etc.) in order to say something is "true". In many ways truth is often quite political.