Epistemic logic can express the principle that everything known is also believed (Kp → Bp) using distinct knowledge and belief operators

Epistemic logic, which in its modern formulation is typically traced to von Wright (1951) and Hintikka (1962), is a formal framework designed to foreground these matters. For an influential introductory text, see Fagin et al. (1995). The formal language of epistemic logic extends that of propositional logic with epistemic operators \({\bf B}_a \phi\) and \({\bf K}_a \phi\), pronounced respectively as ‘agent \(a\) believes that \(\phi\),’ and ‘agent \(a\) knows that \(\phi.\)’ When only one agent