Not-so-Absolute Cosmic Simultaneity

Abstract Cosmic simultaneity is the proposal that we can reconcile absolute simultaneity with relativity by means of the cosmic time function definable in certain cosmological models. In this paper, I add a new criticism to the debate on cosmic simultaneity: once the relevant notion of absoluteness is clarified, a seemingly appealing approach to cosmic simultaneity, the metaphysical approach, proves to be inconsistent. My overall argument proceeds as follows. First, I argue for what I call the Causal Connection Condition (CCC): the fact that two events stand in a certain temporal relation is absolute only if it obtains independently of the occurrence of any causally disconnected event. I then show that, according to metaphysical cosmic simultaneity, whether two events are cosmically simultaneous depends on causally disconnected events. I conclude that metaphysical cosmic simultaneity is inconsistent.