 are often referred to as principles of positive introspection, or for knowledge the ‘KK’ principle. Both principles are deemed acceptable by, e.g., Hintikka (1962) on grounds different from introspection. He argues based on an autoepistemic analysis of knowledge, using a non-Kripkean possible worlds semantics called model systems. Hintikka holds that when an agent commits to knowing \(\varphi\), the agent commits to holding the same attitude no matter what new information the agent will encounter in future. This entails that in all the agent’s epistemic alternatives for Hintikka, all the model sets (partial descriptions of possible worlds) where the agent knows at least as much they now do the agent still knows \(\varphi\). As \(K_{a}\varphi\) thus holds in all the agent’s epistemic alternatives, Hintikka concludes that \(K_{a}K_{a}\varphi\). Likewise Hintikka endorses 4 for belief, but Lenzen raises objections (Lenzen 1978: ch. 4).