A Logic of Plausible Justifications L. Menasché Schechter

Abstract.
In this work, we combine the frameworks of Justification
Logics and Logics of Plausibility-Based Beliefs to build a logic for Multi-
Agent Systems where each agent can explicitly state his justification for
believing in a given sentence. Our logic is a normal modal logic based
on the standard Kripke semantics, where we provide a semantic definition
for the evidence terms and define the notion of plausible evidence
for an agent, based on plausibility relations in the model. This way, unlike
traditional Justification Logics, justifications can be actually faulty
and unreliable. In our logic, agents can disagree not only over whether a
sentence is true or false, but also on whether some evidence is a valid justification
for a sentence or not. After defining our logic and its semantics,
we provide a strongly complete axiomatic system for it and show that
it has the finite model property and is decidable. Thus, this logic seems
to be a good first step for the development of a dynamic logic that can
model the processes of argumentation and debate in multi-agent systems.