Originally Posted by ProfessorDave

A. Truth is really subjective. I would point to numerous writings by Existentialists and Phenomenologists for validation.
B. It is impossible to know what one knows. There is no reliable assessment tool and it would take too long. It would be easier to evaluate what one doesn't know.
3. You can infer what one thinks by their behavior. However, over a century of research has proven that this is a poor indicator of thoughts, often measured as values, attitudes, and beliefs.
D. I agree that reading the manual of any car is time well spent.