 Returning to the indistinguishability interpretation of knowledge, we may then seek to find the epistemological principles which the interpretation is committed to. There is a trivial answer of little direct interest: Let \(\mathsf{EQ}\) be the class of frames with equivalence relations. Then the logic of the indistinguishability interpretation is the set of formulas of \(\mathcal{L}_{K}\) which are valid over \(\mathsf{EQ}\), i.e., the set \(\Lambda_{\mathsf{EQ}}:=\{\varphi\in\mathcal{L}_{K}\colon\mathsf{EQ}\vDash\varphi\}\). Not very informative.