  A fundamental question asked in modal logic is whether a given theory is
consistent. But consistent with what? A typical way to address this question
identifies a choice of background knowledge axioms (say, S4, D, etc.) and then
shows the assumptions codified by the theory in question to be consistent with
those background axioms. But determining the specific choice and division of
background axioms is, at least sometimes, little more than tradition. This
paper introduces **generic theories** for propositional modal logic to address
consistency results in a more robust way. As building blocks for background
knowledge, generic theories provide a standard for categorical determinations
of consistency. We argue that the results and methods of this paper help to
elucidate problems in epistemology and enjoy sufficient scope and power to have
purchase on problems bearing on modalities in judgement, inference, and
decision making.
