Recent work in meta-ontological realism can be roughly divided into 2 approaches: the neo-Aristotelian approach and the Quinean approach. Quinean approach According to the Quinean approach, the goal of ontology is to determine what exists and what doesn't exist. Quine himself developed a specific version of this approach relying on first-order logic and pre-existing scientific theories in order to answer existence-questions. It involves translating these theories into first-order logic formulas. Their ontological commitments are then read off from the existential quantifiers used in the formulas. One idea behind this approach is that scientific theories are our best guess about what is true. But in order for them to be true there should be something there that makes them true: their truthmakers. The existential quantifiers act as a guide to truthmakers. Another approach to answering existence-questions is proposed by Amie L. Thomasson. Her easy approach to ontology differs from Quine's approach in that it relies on common sense instead of science. The approach is easy because it usually starts off from very trivial common-sense premises. For example, an easy argument for the existence of numbers in the philosophy of mathematics can be made in the following way. There are five books on the table. So the number of books on the table is five. Therefore numbers exist. Thomasson's approach differs from Quine's not just concerning her commitment to common sense but also concerning her account of quantification. Neo-Aristotelian approach According to the neo-Aristotelian approach, the goal of ontology is to determine which entities are fundamental and how the non-fundamental entities depend on them. The concept of fundamentality is usually defined in terms of metaphysical grounding. Fundamental entities are different from non-fundamental entities because they are not grounded in other entities. For example, it is sometimes held that elementary particles are more fundamental than the macroscopic objects (like chairs and tables) they compose. This is a claim about the grounding-relation between microscopic and macroscopic objects. A neo-Aristotelian would categorize this claim as an ontological claim. Aristotle himself was also "neo-Aristotelian" in the sense that he held that entities from different ontological categories have different degrees of fundamentality. For example, substances have the highest degree of fundamentality because they exist in themselves. Properties, on the other hand, are less fundamental because they depend on substances for their existence. Jonathan Schaffer's priority monism is a more recent form of neo-Aristotelian ontology. He holds that