Maria M. Syrmich

The paper aims to demonstrate how the problem of object identity can be addressed within four-dimensionalism (T. Sider, K. Hawley, N. Markosian) using the Ship of Theseus paradox as a proper example. Each temporal part must be synchronically (at a given moment in time) identical to the whole – to the entire object, or to its spatiotemporal «worm», – and diachronically (across time) «metaphysically» connected to the other temporal parts, – that will allow us to say that enduring object remains the same. An object is identical to itself in a strict singular sense of itself because essentially (in the Aristotelian sense), at any given moment in time, there exists only one temporal part of the object’s overall spatiotemporal worm. The essence of this temporal part, in turn, is determined by the metaphysical relation that links its different temporal parts, related to different moments in time. Moreover, both the essence of the temporal part of the object and the essence of the object as such are determined by the «significant characteristics of the object», which are both a proper part of the object and a proper part of its corresponding temporal part. We argue that temporal parts can be related to the whole object by the mereological relation of parthood, which is transitive, reflexive, and antisymmetric, and mereological relation of overlapping can also operate between them. The role of mereology here lies in the ability to interpret «the significant characteristics of an object» simultaneously as both a proper part of the object as such – as a proper part of object’s overall spatiotemporal worm – and as a proper part of the corresponding temporal part.