 We cannot digress here into modal realism (for discussion of possible worlds, see entries on  Possible Worlds  and  David Lewis:  Modal Metaphysics), but turn specifically to Almeida’s cosmological argument. He argues that whereas cosmological arguments in the past commenced with an initial premise that was taken to express a contingent fact known a posteriori, “facts about change, causation, contingency, and objective…becoming are not usefully characterized as a posteriori facts” (2018: 3). He advances a cosmological argument with what he takes is an a priori fact: the pluriverse and everything in it, including all actualia and all possibilia, exist necessarily. This, he claims, is knowable a priori and according to the PSR requires an absolute explanation. Part of his novel approach is his contention that every proposition in the argument expresses a necessary fact known a priori, and that a priori propositions also require an explanation.