Why Do We Need Justification Logic?

In this paper, we will sketch the basic system of Justification Logic, which is a general logical framework for reasoning about epistemic justification. Justification Logic renders a new, evidence-based foundation for epistemic logic. As a case study, we compare formalizations of the Kripke ‘Red Barn’ scenario in modal epistemic logic and Justification Logic and show here that the latter provides a deeper analysis. In particular, we argue that modal language fails to fully represent the epistemic closure principle whereas Justification Logic provides its adequate formalization.