Abstract The inadequacy of epistemic modal logics for representing the reasoning held by realistic agents characterised by bounded cognitive and computational resources has been clear since the beginning. These logics require agents i) to be logically omniscient, i.e., to know all the logical consequences of what they know, and ii) to manage in their reasoning higher-order knowledge to a possibly unbounded degree. In this talk, we address this problem in order to provide a notion of knowledge held by realistic agents using Kripke structures. To this end, we follow the depth-bounded approach to logic and offer an incremental characterization of epistemic modal logics. The latter result as the limit of infinite hierarchies of weaker logical systems that satisfy minimal rational requirements and can be sensibly used as formal models of the deductive power of resource-bounded agents. In the resulting family of logics, called Bounded Epistemic Logics, i) the assumption of logical omniscience can safely be accepted because the consequence relation of classical logic is waived in favour of weaker and tractable ones, and ii) the complexity of the agents’ accessibility relations is limited to the effect that their higher-order knowledge is bounded.
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