Axiom S5

Axiom S5 is a principle in modal logic that describes how knowledge or beliefs work when considering possibilities. It states that if something is necessarily true (true in all scenarios), then it is necessarily true that you know it. Also, if you know something, then you consider it possible that it is true, and if something is possible, then it is necessarily possible. These rules ensure a logical system where knowledge is both accurate and introspective, meaning you know what you know and know what you don’t know, under ideal conditions.