Sceptics about substantial disputes in ontology often argue that when two philosophers seem to disagree on a quantified claim, they are actually equivocating on the notion of existence that they are using. When temporal elements play a central role, as in the debate between presentists and eternalists, the hypothesis of an equivocation with respect to existence acquires more plausibility. However, the anti-sceptic can still argue that this hypothesis is unjustified.