You can't know whether something is delusional unless you have a context in which to view it. In the context of my normal human activities, people are delusional who think they can fly. In another context, everything I think and "know" might be completely false or illusory.
I'll settle for truth-in-context: in the world view in which I think and function, some things are true and some aren't, and that's good enough.
I'll settle for truth-in-context: in the world view in which I think and function, some things are true and some aren't, and that's good enough.