 There are also other alternatives. An interesting proposal, discussed in Lenzen (1978) and Williamson (2002), follows the other direction: start from a chosen notion of knowledge, and then weaken it in order to obtain a ‘good’ (e.g., consistent, introspective, possibly false) notion of belief. These ideas have been discussed in formal settings. In Stalnaker (2006), the author argues that the “true” logic of knowledge is the modal logic S4.2, given by the standard K axiom \((K(\varphi \rightarrow\psi) \rightarrow (K\varphi \rightarrow K\psi))\) and the generalization rule \((K\varphi\) for every validity \(\varphi)\), together with veridicality \((K\varphi \rightarrow \varphi\): knowledge is truthful), positive introspection \((K\varphi \rightarrow KK\varphi\): if the agent knows \(\varphi\), then she knows that she knows it) and the ‘convergence’ principle \((\hK K\varphi \rightarrow K\hK\varphi\): if the agent considers it possible to know \(\varphi\), then she knows that she considers \(\varphi\) a possibility). In this setting, Stalnaker (2006) argues that belief can be defined as the epistemic possibility of knowledge, that is,