A core commitment of the popular possible world semantics for modal logics is that a proposition is possible just in case this proposition is true at a possible world. Call this commitment the Fundamental Theorem of World Theory (FTWT). While FTWT can be assumed without loss of generality, at least mathematically, when studying most of the propositional modal logics we are interested in, FTWT reveals itself in full strength inside modal logic with propositional quantifiers. In this talk, we discuss how FTWT is formalized in modal logics with propositional quantifiers and examine some purported ways to show FTWT "logically". Eventually, we argue that they are not successful, and along the way, we mention some completeness results for modal logic with propositional quantifiers in which we have modalities of possibility and actuality.