Epistemology is the study of knowledge and belief, a branch of philosophy that asks, “what is truth, how do we know, and how can we prove it”.

This includes examining what we know, what we can know, how we can know it, how we can prove we know it, what we can’t know, how we can prove we don’t know, what the difference between opinion and fact are, what the difference between empirical and reasoned evidence is, what the difference between truth and belief is, and more.

Some of the most important philosophical works are epistemological, as a theory holds a lot more weight when you can actually prove it by accepted measures. See our page on Hume’s fork and Kant’s a Critique of Pure Reason for a starter kit, or see Stanford Encyclopedia of Philosophy’s page on Epistemology for the AP version, or see this article on knowledge, opinion, and fact.

  • Knowledge: Objective. Something we know to be true with a high degree of certainty. EX. A well worn scientific theory like F=ma, 1+1=2, a ripe apple taste sweet. Subjective. Something we know, even with conviction, but that is not known with a high degree of certainty. EX. “All humans have a natural a right to life, liberty, and happiness.”
  • Truth: Objective. Something that is undoubtedly proven to be so through facts. When we combine our tools of knowledge, belief, reason, and sensory data, along with acceptance, verification, justification, and perspective, the end result will ideally be truth. The key difference between knowledge and truth is that, unlike knowledge, truth exists regardless of our ability to prove it with certainty.
  • Belief: Subjective. Broadly, ideas we feel to be true, but can’t fully prove empirically or rationally with facts, but hold a high sense of certainty anyway. We may have faith in our beliefs, and may be able to prove them with reason, but we don’t have objective and certain evidence of their truth. Even a scientific theory can be a belief, after-all, theories are falsifiable despite all the facts pointing to them.
  • Opinions: Subjective. Ideas we feel to be true, we can use facts to back them up, but we are using arguments based on our beliefs and emotions, not pure facts.
  • Empiricism: Knowledge through empirical evidence (information from the senses). Facts about the world.
  • Rationalism: Knowledge through ideas (information originating in our minds). Facts about ideas.
  • Skepticism: In this case, being skeptical that rationalism (pure reason) can result in true knowledge about the world. Can be interpreted broadly of skepticism about both empirical and rational knowledge. For instance, Kant suggests fusing the two styles as, “our senses themselves could be tricking us”.
  • Justification: Our ability to justify our reasoning using any of the above technologies and more epistemological tools. We can’t just say we know something, we must give a justification.
  • Myth: Subjective. Beliefs we are certain about, but are based on misinformation and opinion rather than fact. Common knowledge that isn’t in fact truth.
  • Absurdity: Treating belief as fact, or being certain of a belief (but accepting the belief on faith), even going as far as to provide reason-based justification to prove the belief (see Newton’s Arian beliefs for example), when ultimately it is accepted that the belief can never be proven true. It is absurd to accept things within the sphere of belief as truths, treating them like they are in the sphere of fact, and actually basing our lives (ethics, morals, actions) around something of which we can never be certain. The basis for existentialism.

The Difference Between Fact and Opinion

Facts are things that are the case for sure, they are stated plainly and without bias. Opinions meanwhile inject subjectivity and bias. Since most content in any form contains at least some subjectivity and bias, it is rare to find pure facts and common to find opinion.