On What There Is by Willard Van Orman Quine

An influential defense of a formal, quantifier-based approach to ontology: the essay argues that existence is expressed by the existential quantifier rather than by a special predicate, and that our ontological commitments consist in whatever entities our best theories quantify over. It rejects Meinongian nonentities and other devices that posit strange kinds of being, urging that disputes about what exists be settled by analyzing the variables and paraphrases required by competing theories so that mathematical or abstract objects are accepted only if indispensable to our best scientific descriptions. The result is a pragmatic, theory-driven criterion for deciding what there is.