As part of their education, Tibetan Buddhist monks train in logical debate. One key principle to these debates is the declaration of “level of truth”. In Buddhism, there are two levels of truth: “common sense truth (relative truth)” and “ultimate truth” (wiki). It is felt that in order to avoid unnecessary contradictions and confusion, the debater must always be clear on declaring the level of truth in which his arguments lie.
I won’t pretend to understand the depth of this philosophical tool, but when reading it years ago, and seeing it when I visited Dharamsala, I found it a convenient tool on a more profane level. In coffe-shop debates, I find that declaring the equivalent of “levels of truth” helps avoid unnecessary misunderstandings. For example, on the absolute level, we can say “You can not prove anything”, but usually when debating, we don’t want to assume that level, we must establish rules so we can make progress. You need to make an operational definition of what qualifies as proof.
My related posts: My Cognitive Narratives
Triangulations 
Perfect.