- certainly true
- probably true
- unable to demonstrate false
- unable to demonstrate true
- probably false
- certainly false
- we need to believe it to be true
- we must have justification for that belief,
- we can put a reserve clause in, that given sufficient reason, we can change our mind.
Keeping in mind that concepts exist, well perhaps exist is not the right word; they have no physical existence. The stoics said the subsist, but concepts are real and can be anywhere on the truth scale. Perhaps existence is the not the right property to assign to this mental object. Concepts appear to lie outside of space, and some seem to lie outside of time as well, but are dependent on consciousness.
Anyway, these things are concepts and once we learn them, they become mental tools and mental object to be used in evaluation. It would be nice if there was a book of mental tools.
But then what do I know?