Overview

Ontology is the study of being. It asks the most fundamental question: “What exists?” It categorizes everything in reality into basic types (categories) and explores how they relate to each other.

Core Idea

The core idea is categorization of reality. Just as a biologist classifies animals, an ontologist classifies everything. Is a number real? Is a hole real? Is a possibility real?

Formal Definition

The philosophical study of the nature of being, becoming, existence, or reality, as well as the basic categories of being and their relations.

Intuition

Imagine making a list of everything in the universe.

  • Tables? Yes.
  • Atoms? Yes.
  • The number 7? Maybe.
  • Harry Potter? No (or maybe yes, as a fictional character?). Ontology is the set of rules for making that list.

Examples

  • Universals vs. Particulars: Is “Redness” a thing that exists (Universal), or are there just many red things (Particulars)?
  • Abstract Objects: Do numbers and logic exist independently of human minds (Platonism)?
  • Social Ontology: Do money and nations exist in the same way mountains do? (Institutional facts).

Common Misconceptions

  • Misconception: It’s about the meaning of life.
    • Correction: That’s existentialism or ethics. Ontology is about the structure of reality, not its purpose.
  • Misconception: It’s useless wordplay.
    • Correction: Computer science uses “ontologies” to structure databases and AI knowledge graphs.
  • Metaphysics: The broader field containing ontology.
  • Epistemology: The study of knowledge (How do we know what exists?).
  • Taxonomy: Classification in biology (a specific type of ontology).

Applications

  • Computer Science: Semantic Web and Knowledge Representation rely on formal ontologies.
  • Science: Theoretical physics often forces us to revise our ontology (e.g., particles are actually excitations of fields).

Criticism and Limitations

  • Quine’s Criterion: “To be is to be the value of a variable.” Some argue ontology is just about what our best scientific theories say exists, not a separate philosophical inquiry.

Further Reading

  • On What There Is by W.V.O. Quine
  • Metaphysics: A Contemporary Introduction by Michael J. Loux