Is Sider still a perdurantist?
In Writing the Book of the World (2011) Theodore Sider claims that on the fundamental level of reality there are no objects composed of parts, which makes his view a version of mereological nihilism. However, in his previous book entitled Four-Dimensionalism (2001), Sider endorses mereological universalism, the thesis that every class of objects has a mereological fusion, i.e. that there exists an additional object containing those objects as parts, which plays a crucial role in his argument from vagueness in favour of perdurantism, that is the thesis of the existence of temporal parts of material objects. In this paper I will investigate whether Sider can still be a perdurantist in spite of his latest commitment to mereological nihilism.