Metaphysics
Ontology
This guide helps you get your bearings in Ontology before you start exploring the interactive timeline, framework graph, and concept maps.
Before You Dive In
- Ontology asks the most basic question in philosophy: what exists? And more precisely, what categories of things exist (objects, properties, events, numbers, possibilities)?
- The central historical debate is between realism (universals exist independently) and nominalism (only particulars exist; "redness" is just a word we use).
- Start with the problem of universals — it's the clearest entry point and connects to philosophy of science, mathematics, and language.
- Contemporary ontology is increasingly formal: debates about composition (when do parts form a whole?), persistence (how do objects survive change?), and grounding (what explains what?).
- Quine's criterion — "to be is to be the value of a bound variable" — transformed ontology by tying existence claims to the logical structure of our best theories.
Key Terms to Know
UniversalsProperties or relations (like redness or being taller than) that can be instantiated by multiple particulars.
NominalismThe denial that universals exist — only concrete particulars are real; general terms are conventions.
MereologyThe study of parts and wholes: when do objects compose a further object?
GroundingA relation of metaphysical explanation: one fact obtains in virtue of another (e.g. mental facts grounded in physical facts).
Ontological commitmentQuine's idea that a theory is committed to the existence of whatever its quantifiers range over.
Common Confusions
Confusing ontology with a catalogue of everything that happens to exist — ontology is about the categories and structure of being, not a list of entities.
Thinking the problem of universals is a medieval relic — it's active in contemporary metaphysics, philosophy of mathematics, and philosophy of science.
Assuming ontological questions are meaningless because they can't be settled empirically — Quine, Lewis, and others showed how they connect to scientific and logical inquiry.
Recommended Reading
Word and Object— Willard Van Orman Quine
1960On the Plurality of Worlds— David Lewis
1986Metametaphysics: New Essays on the Foundations of Ontology— David Chalmers, David Manley & Ryan Wasserman
2009How to Use the Interactive View
1
Explore the timeline
Open the interactive view and scan the framework timeline. Which frameworks came first? Which ones overlap? Where are the big transitions?
2
Read the articles
Click into individual frameworks to read what each one claims, where it came from, and how it relates to its neighbors.
3
Check the concept map
See how the key ideas within a framework connect. This is useful for figuring out what to learn first and what depends on what.
4
Test yourself
Take the quiz for any framework you've read about. It's a quick way to find out whether you actually understood the core ideas or just skimmed them.