Red is the axiomatic truth - true because I know and you don't, and if you don't take my word for it, then we don't have a game, or a bond of trust we can base a game upon. It's the truth of Witches.

The other truth I made extensive use of is the Blue Truth; essentially, a hypothesis that challenges the Red. Within a particular scenario, I occasionally gave someone else the right to use the Blue Truth to espouse theories that challenged my assertions, and I could only respond in Red or not at all. Blue Truth is, more or less, the truth of the Detective.