Ontology vs Epistemology: What’s the Difference?

People search for ontology vs epistemology because both are core areas of philosophy—and it’s easy to mix them up. What is ontology and what is epistemology? In short: ontology is the study of what there is; epistemology is the study of what we know and how we know it. If you’ve ever wondered what’s the difference between ontology and epistemology—and how they relate—this article is for you.

Ontology vs epistemology in short: ontology asks what exists—what kinds of things, properties, or structures there are in reality. Epistemology asks what we know, what counts as justification, and how we tell truth from error. So ontology vs epistemology is “what there is” vs “what we know (and how we know it).” They’re related—your ontology can constrain your epistemology and vice versa—but they’re different questions. Below: what each is, how they differ, how they connect, and where to go deeper with what is metaphysics, epistemology for beginners, and learning paths on schrodingers.cat.

What is ontology?

Ontology is the branch of philosophy (and part of metaphysics) that asks what there is—what exists. So what is ontology in practice? It asks: What kinds of things are there? Are there only concrete, material things, or also abstract objects (numbers, properties, possibilities)? What is it for something to exist? How do we categorize what there is (substance, property, event, etc.)? So ontology is the study of being and what there is—it doesn’t, by itself, tell you how we know what there is; that’s epistemology. For how ontology fits into metaphysics, see what is metaphysics; for how we know, see epistemology for beginners.

What is epistemology?

Epistemology is the branch of philosophy that asks what we know and how we know it. So what is epistemology in practice? It asks: What is knowledge? What is justification? What counts as evidence? How do we tell truth from error? What are the sources of knowledge (perception, reason, testimony)? So epistemology is the study of knowledge and justification—it doesn’t, by itself, tell you what exists; that’s ontology. In ontology vs epistemology, epistemology is the “how we know” side. For a friendly intro, see epistemology for beginners; for how epistemology relates to metaphysics, see what is metaphysics.

Ontology vs epistemology: how they differ

Ontology vs epistemology can be summarized along a few axes:

Question. Ontology asks: What is there? What exists? What are the categories of being? Epistemology asks: What do we know? How do we know it? What justifies our beliefs? So ontology vs epistemology is “what there is” vs “what we know and how we know it.”

Focus. Ontology focuses on reality—the structure of what exists. Epistemology focuses on our access to reality—belief, evidence, justification, and knowledge. So what is ontology in focus? Being and existence. What is epistemology in focus? Knowledge and justification.

Method. Ontology often uses conceptual analysis, thought experiments, and sometimes results from science to decide what there is. Epistemology often uses conceptual analysis, thought experiments, and reflection on how we form and justify beliefs. So ontology vs epistemology in method: both can use similar tools, but they’re asking different questions—one about the world, one about our relation to the world.

Examples. Ontology: Are there numbers? Are there minds? Are there possible worlds? Epistemology: What is knowledge? Is it justified true belief? What counts as evidence? So ontology vs epistemology comparison in examples: ontology gives you a catalogue of what exists; epistemology gives you a theory of how we know (or fail to know).

The bottom line: ontology vs epistemology is a useful distinction—ontology is about what there is; epistemology is about what we know and how we know it. They’re not the same, but they’re often studied together. For more on metaphysics (which includes ontology), see what is metaphysics.

How ontology and epistemology connect

Ontology and epistemology are related. Your ontology (what you think exists) can constrain your epistemology (what you think we can know)—e.g. if you think only physical things exist, you might think knowledge must be grounded in perception and science. Your epistemology can constrain your ontology—e.g. if you think we can only know what we observe, you might be wary of positing unobservable entities. So ontology vs epistemology isn’t “pick one”—it’s “two questions that interact.” Philosophers often do both; metaphysics (including ontology) and epistemology are core areas in any philosophy curriculum. For paths on metaphysics and epistemology, browse learning paths or the philosophy map.

Key questions in ontology vs epistemology

Ontology (what is there?): What exists? Are there abstract objects? What is a person? What is identity over time? What are properties and relations? So what is ontology in terms of content? It’s the sustained, argued treatment of these questions.

Epistemology (what do we know?): What is knowledge? What is justification? What are the sources of knowledge? Can we know the external world? What is skepticism? So what is epistemology in terms of content? It’s the sustained, argued treatment of these questions.

So ontology vs epistemology comparison in practice: ontology builds a picture of reality; epistemology builds a picture of how we grasp (or fail to grasp) that reality. For more on both, see what is metaphysics and epistemology for beginners.

Where to go deeper

You don’t have to choose between ontology and epistemology—most philosophers work on both at different times. On schrodingers.cat you can: (1) read what is metaphysics to see how ontology fits into metaphysics; (2) read epistemology for beginners for a friendly intro to epistemology; (3) browse learning paths for paths on metaphysics, ontology, or epistemology; (4) use the path quiz to get a path that fits you; (5) try Socratic dialogue on questions about what exists or what we know. So ontology vs epistemology is a useful map—use it to see the difference, then explore both with paths and dialogue on schrodingers.cat.

Frequently Asked Questions

What is the difference between ontology and epistemology?

The difference between ontology and epistemology is the question they ask: ontology asks what there is—what exists and how it is categorized. Epistemology asks what we know and how we know it—knowledge, justification, and evidence. So ontology vs epistemology is “what there is” vs “what we know and how we know it.”

What is ontology?

What is ontology? Ontology is the branch of philosophy (and part of metaphysics) that studies what there is—what exists, what kinds of things there are, and how we categorize being. It’s the study of reality in the sense of “what is there,” not “how we know about it.”

What is epistemology?

What is epistemology? Epistemology is the branch of philosophy that studies knowledge and justification—what we know, how we know it, what counts as evidence, and how we tell truth from error. It’s the study of knowledge, not (directly) of what exists.

Is ontology part of metaphysics?

Yes. Ontology is the part of metaphysics that asks what there is. Metaphysics is broader—it also studies cause, identity, possibility, and the structure of reality. So in ontology vs epistemology, ontology is a branch of metaphysics; epistemology is a separate branch of philosophy. For more, see what is metaphysics.

Conclusion

Ontology vs epistemology is a core distinction: ontology is about what there is; epistemology is about what we know and how we know it. They’re different questions but they connect—your views in one can constrain your views in the other. What is ontology and what is epistemology? Use the comparison as a map—then go deeper with what is metaphysics, epistemology for beginners, and learning paths on schrodingers.cat.

Summary. Ontology vs epistemology: what there is vs what we know. Use the distinction as a map; then explore metaphysics and epistemology on schrodingers.cat.

What is metaphysics → · Epistemology for beginners → · Learning paths → · Path quiz →

Key takeaway: Ontology vs epistemology: ontology studies what there is; epistemology studies what we know and how we know it. For how they fit with metaphysics, see what is metaphysics on schrodingers.cat.