Metaphysicians who are aware of modern physics usually follow Putnam (1967) in arguing that Special Theory of Relativity is incompatible with the view that what exists is only what exists now or presently. Partisans of presentism (the motto ‘only present things exist’) had very difficult times since, and no presentist theory of time seems to have been able to satisfactorily counter the objection raised from Special Relativity. One of the strategies offered to the presentist consists in dropping out 'There Are No Privileged Observers'. Two meta-ontological moves follow this strategy: either existence is relativized to inertial frames, or existence is fragmented into pieces (there is no one encompassing reality but many ontological realities, one for every inertial frame). The relativistic strategy has been accused of counterfeiting, since the meaning of the concept of existence would be incompatible with its relativization. Therefore, existence could only be relativistically invariant. In this presentation, I shall examine whether such an accusation hits its target, and I will do this by examining whether the different criteria of existence that have been suggested by the Philosophical Tradition from Plato onwards imply that existence cannot be relativized. In regard to the fragmentalist strategy that challenges ontological monism, I will discuss the standard meta-ontological arguments in favor of monism to show that they can be resisted.
Marion et al. (2025) studied this question.