Five questions -- The new anti-metaphysicians -- Being, existence, and ontological commitment -- Existence, ontological commitment, and fictional entities -- Can variables be explained away? -- Quine's 1946 lecture on nominalism -- Alston on Ontological commitment -- A theory of properties -- What is an ontological category? -- Relational vs. constituent ontologies -- Can merological sums change their parts? -- Causation and the mental.