Theory of knowledge
What Is Epistemology?
Epistemology is the philosophy of knowledge: what knowledge is, how belief is justified, and how far skepticism should go.
Short answer
In short, epistemology studies knowledge and justified belief—how perception, reason, memory, and testimony support (or fail to support) what we claim to know.
Knowledge and justification
A classic starting point treats knowledge as justified true belief, refined after Gettier-style counterexamples. Debates continue about reliability, evidence, understanding, and intellectual virtues.
Sources of justification include perception, memory, introspection, reason, and testimony—each with characteristic strengths and failure modes.
Skepticism and response
Skeptics ask whether we can know the external world, other minds, or the future. Responses range from foundationalism and coherentism to contextualism and pragmatist accounts of inquiry.
Why epistemology matters
Questions about expertise, misinformation, scientific evidence, and AI outputs are epistemological before they are merely technical. Clear standards of evidence improve public and personal judgment.
Frequently asked questions
What is epistemology in simple terms?
It is the study of knowledge and justified belief—how we know what we know.
What is the difference between epistemology and ontology?
Ontology asks what exists; epistemology asks how we can know it. A research project often needs both: what kinds of things are under study, and what counts as evidence for claims about them.
What are examples of epistemology?
Everyday examples include trusting a map, checking a witness, or asking whether an AI output is knowledge or only a fluent guess. In philosophy: Can perception justify belief? What makes testimony trustworthy? Does science give knowledge or only models?
How is epistemology different from psychology?
Psychology describes how cognition works; epistemology evaluates norms of good believing and knowing.
From the archive
Read alongside this guide
“Justice is doing one's own work and not meddling in others'.”
“Love is the desire for the perpetual possession of the good.”
“Let us not become haters of argument — that is a great danger to the soul.”