  There are several design decisions made. Justification Logic starts  with the simplest base: classical Boolean logic, and for good reasons. Justifications provide a sufficiently serious challenge on  even the simplest level. The paradigmatic examples by Russell,  Goldman-Kripke, Gettier and others, can be handled with Boolean  Justification Logic. The core of Epistemic Logic consists of modal  systems with a classical Boolean base  (K, T, K4, S4, K45, KD45, S5,  etc.), and each of  them has been provided with a corresponding Justification Logic  companion based on Boolean logic. Finally, factivity of  justifications is not always assumed. This makes it possible to  capture the essence of discussions in epistemology involving matters  of belief and not knowledge.