Epistemic logic

Modern treatment of epistemic logic began in the 1950s when some philosophers noticed (as scholastics had done before them) certain regularities in the logical behaviour of the concept of knowledge (for example, that knowing a conjunction is equivalent to knowing all its conjuncts) and began to systematize them. Initially these regularities were presented in the form of an axiomatic-deductive system, as in other branches of logic. Later, questions began to be asked concerning the model theory on which such an ‘epistemic logic’ is based. Still later, the concrete interpretation of this model theory has become an issue. In this way, gradually a bridge has begun to be forged from purely logical questions to such central epistemological questions as those concerning the objects of knowledge, different kinds (or even senses) of knowledge (and their interrelations), the intensional character of knowledge, the de dicto versus de re distinction, and so on.