This chapter considers the possibility of Nihilism, that nothing exists, and its alternative, Aliquidism, that something exists. This will lead us into an investigation of the point of positing existing things. The chapter looks at the debate between Monists, who believe in only one thing, and Pluralists, who believe in many. It also considers both radical and more moderate forms of both Nihilism and Monism, including, for example, Priority Monism. The chapter examines four arguments for Monism: those of Parmenides, Spinoza, (...) Bradley, and Jonathan Schaffer. Parmenides of Elea authored a single work, a poem traditionally titled On Nature. In the first part of this poem, Parmenides seems to be arguing for Monism. Baruch Spinoza offered a set of metaphysical arguments that could be interpreted as attempting to show that only one thing exists. The chapter considers the import of Bradley's Regress for Constituent Realism, UPRealism combined with Constituent Ontology. (shrink)