Comments on Theodore Sider’s Four Dimensionalism

Abstract

This chapter refutes Theodore Sider's arguments on anti-commonsensical ontology in his book, Four Dimensionalism. Sider's defense consists of temporal parts and unrestricted mereological composition—that is, his definition of an object's “unity” is the sum of parts existing throughout time. Four-dimensionalism proposes a distinction between the objects observed by non-philosophers and the additional objects viewed by four-dimensionalists (we will call them “Siderian objects”)—the mereological construction of temporal parts. This constitutes the four-dimensionalist premise on the question of “what exists.” However, a reduction ad absurdum argument explores the ontology and linguistic implications of four-dimensionalism, in turn demonstrating that an acceptance of the existence of Siderian objects is not applicable to plain language. Ergo, Siderian objects do not exist. And if Siderian objects do not exist, then four-dimensionalism is false.