What's the Difference Between Ontology and Epistemology?

Ontology and epistemology are two of the words most likely to stall new researchers. In most social science, education, health and business programs, your examiners will usually expect a clear position on both, and most textbook explanations make the question harder, not easier.

Having coached 10,000+ students, we’ve found the fix is rarely more philosophy. It’s a plain answer to two questions. In this post, I’ll explain each term in plain language, put them side by side, and show you practical examples from a real Master’s thesis project.

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What is ontology?

Think of ontology as the study of reality itself. It asks the fundamental question: what actually exists? When you’re doing research, ontology is about deciding what counts as real and what doesn’t. Is something a concrete fact, or is it a perception, an idea, or something that a community has agreed upon?

Ontology is a big, philosophical question, and that’s exactly why it can feel a bit abstract. But here’s the thing: every researcher has an ontological position, whether they’ve thought about it explicitly or not. Your ontological stance shapes what you’re willing to study and what you believe counts as valid phenomena worth investigating.

A common way to frame it is as two positions. Realism holds that a real world exists independently of human experience, so it can be studied as it is. Relativism holds that reality is constructed by the people who experience it, so there is no single “true” reality to uncover. That’s the framing Katie Moon and Deborah Blackman use in their guide to ontology and epistemology for researchers, and it’s a good place to begin.

What is epistemology?

Epistemology is about knowledge itself. It answers questions like: what is knowledge? How do we know if something is true? What kinds of evidence count as good evidence? How can we ever be certain about anything?

In your dissertation or thesis, you’re creating new knowledge. That’s the whole point. So having a clear epistemological framework upfront is crucial, because you need to be able to explain what knowledge is and how you’re going to create it. Your epistemology describes your approach to building knowledge in your field.

The two positions you’ll meet most often are positivism, the view that knowledge comes from objective observation and measurement, and interpretivism, the view that knowledge comes from understanding people’s meanings and experiences. A third, pragmatism, chooses whatever works best for the research question. All three are explained, with examples, in our guide to research philosophy.

Ontology vs epistemology at a glance

Seen side by side, the difference is easier to hold onto. Here’s how the two compare on the questions that matter for your study.

	Ontology	Epistemology
The question it asks	What is real?	How do we know what’s real?
What it’s about	The nature of reality: what exists to be studied	The nature of knowledge: what counts as evidence
Common positions	Realism and relativism	Positivism and interpretivism
The question it raises in a study of burnout	Does burnout exist apart from how teachers describe it?	Can a questionnaire tell me about burnout, or do I need to hear teachers describe it?
Where it shows up in your dissertation	The opening of your methodology chapter	Your justification for how you collect and analyze data

Notice that the epistemology question is hard to answer until the ontology question is settled. That’s why most methodology chapters state ontology first.

How to identify your position

Start with ontology, because your epistemology hangs on it. Ask yourself whether the thing you’re studying exists independently of the people involved, like a tree’s death, a blood pressure reading or a company’s revenue, or whether it’s shaped by how people understand it, like workplace culture or professional identity. Your answer puts you closer to realism or to relativism.

Then turn to epistemology. The best place to start is by reading about different types of knowledge. If you don’t have a textbook on hand, we often recommend The Oxford Handbook of Epistemology as a solid starting point. Once you’ve refreshed your understanding of the different epistemological approaches, think about which one fits your research question and your goals.

What type of knowledge are you trying to create?

Are you interested in practical, applied knowledge or theoretical knowledge?

Knowledge based on lived experience?

Let these questions guide you toward the epistemological framework that fits your work.

For example, if you’re an educator researching teaching practices, you might draw on practitioner knowledge. This is knowledge that educators have gained through doing their work, day in and day out. The key is matching your epistemology to your research question and what you’re trying to accomplish.

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Why both concepts matter

You might be wondering why you need to think about both of these concepts. Here’s why: ontology shapes what you believe exists and is worth studying (your reality), while epistemology shapes how you’ll go about studying it and what counts as proof (your knowledge). They work together.

Your ontological position determines what phenomena you’re interested in, and your epistemological position determines how you’ll investigate those phenomena. They’re two sides of the same philosophical coin, and getting clear on both helps you build a coherent research design.

To see how much difference they make, let’s take one topic and run it through two different positions.

Same topic, two entirely different studies.

I’d use this as a test for your own draft: if your methods don’t follow from your ontology and epistemology, that’s the gap an examiner is most likely to question.

How to state your position

If you’re still feeling stuck after reading some theory, do yourself a favor and look at dissertations and theses that have already been completed in your field. Find ones that have an ontology or epistemology section and read how other researchers have framed these concepts. Your field likely has conventions and preferred approaches, and seeing how others have tackled this problem can give you concrete examples to work from.

Here’s what a clear statement looks like. This one comes from a Master’s thesis in environmental science at Cornell, a mixed-methods study of farming communities in Nepal. Watch how it names its position, then explains why it fits the field.

In a few sentences, the passage names its position (realism), defines it with a citation, ties it to the field (“SES” here means social-ecological systems) and makes it concrete with a single image. The epistemology section that follows then opens by building on it.

You can make the same four moves in your own chapter, whatever position you take:

1. Name your position, such as realism or relativism.
2. Define it with a citation to the source you’re drawing on.
3. Tie it to your field, saying why it suits what you’re studying.
4. Make it concrete with one example or image from your own topic.

Then do the same for your epistemology.

You don’t need to reinvent the wheel. Instead, learn from what’s already been done in your discipline and adapt it to your own research context. If you need a hand deciding what’s right for your study, book a free chat with one of our friendly Grad Coaches.

Still have questions?

Which comes first, ontology or epistemology?

Ontology usually comes first, because what you believe exists sets the limits of what you can claim to know about it. A researcher who sees a phenomenon as socially constructed can’t sensibly claim to measure its one true value. Most students settle the two together, but stating ontology first makes the logic easier for an examiner to follow.

Do I need an ontology section in my dissertation?

It depends on your field and your program. Social science, education, health and business dissertations, especially qualitative and mixed-methods ones, usually state both an ontology and an epistemology in the methodology chapter. Many lab-based and quantitative theses never use either word, because their position is taken for granted. Check your program’s handbook and two or three recent dissertations from your department.

Is positivism an ontology or an epistemology?

Positivism is usually described as an epistemology, a view that knowledge comes from objective observation and measurement. It’s commonly paired with a realist ontology, the view that reality exists independently of the researcher. That’s why many methodology textbooks treat positivism, interpretivism and pragmatism as complete research philosophies that carry both positions.

What is axiology in research?

Axiology is the third branch of research philosophy, alongside ontology and epistemology. It deals with values: the role your own values and judgments play in how you conduct and interpret your research. It sits alongside the other two in Saunders’ research onion, which is common in business and management programs, so those programs may ask for a short statement of it too.

How does methodology differ from ontology and epistemology?

Ontology is your view of what’s real, epistemology is your view of how you can know about it, and methodology is the plan you follow to find out. The first two are beliefs; methodology turns them into decisions about design, data and analysis. A realist, positivist position tends to lead to a quantitative methodology, and a relativist, interpretivist one to a qualitative one.

Is phenomenology an ontology or an epistemology?

In a typical dissertation or thesis, phenomenology is best treated as a methodology: an approach to studying how people experience something, most often through in-depth interviews. It rests on an interpretivist epistemology, because it values participants’ own accounts, and it sits toward the relativist end on ontology. If you use it, state it as your methodology and give your ontology and epistemology separately.

What are the four types of ontology in research?

There isn’t one agreed list of four. Different methodology textbooks divide the territory in different ways, and some add positions such as critical realism or nominalism. For most dissertations, the useful distinction is between realism, where reality exists independently of us, and relativism, where people construct it. Place yourself on that spectrum and name the textbook whose terms you’re using.

How do I write my research paradigm section?

Name your paradigm, such as positivism, interpretivism or pragmatism, then state the ontology and epistemology it carries, each with a citation. Explain in a sentence or two why it suits your research question, and show how it leads to your methods. A few short paragraphs is enough for most programs; examiners look for consistency more than length.

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