A Brief Introduction to Epistemology

Photo by Tim Green, Creative Commons

By Dr. Tom Kerns / 01.18.2012
Professor of Philosophy
North Seattle College

The history of western thought is usually divided into four main periods, the ancient, mediaeval, modern, and contemporary periods. We’ve been studying the ancient period and now we’re going to move past the mediaeval period and into the modern period. The mediaeval philosophers were concerned with a very wide range of philosophical questions, but the focus of many of them was what we might call metaphysical and/or theological. These questions largely concerned the nature of the universe, how things are set up in the cosmos, what part God plays in everything, how human beings should act in order to be aligned with the ultimate laws of being, and so on. These philosophies made claims about the ultimate nature of being, about God, about human beings’ place in the cosmos, and similar themes.

At the beginning of the modern period, though, some philosophers began to question these claims and to wonder how anyone could know whether they were true or not. This led to their wondering how it is that human beings can know anything, and then to trying to figure out what counts as true and real knowledge as opposed to mere opinion or belief. This philosophical effort came to be termed “epistemology.”

NASA, Public Domain

For example, consider the claim that the earth is round. You would perhaps say that you “know” the earth is round rather than that you just “believe” the earth is round, or that it is merely your “opinion” that the earth is round. But what would you say is the basis for your knowing that? On what is your knowledge about the shape of the earth founded? You have probably not personally been far enough away from the earth to actually see its roundness, so your knowledge is probably not based on direct personal experience. Perhaps you have seen photographs of the earth from a distance, but then in that case you are relying on what other people tell you about those photographs, that they are actually photographs of the earth, that they have not been tampered with to make the earth appear round, etc. So your knowledge about the roundness of the earth is partly grounded in your acceptance of the claims of some people you take to be trustable authorities. You choose to believe what they tell you. So your “knowing” about the shape of the earth is partly grounded on some “beliefs” you choose to accept.

The fact that many other people, or even that most other people, share your beliefs does not actually increase the likelihood that your beliefs are true. We all know of beliefs that almost everyone in the past used to hold: for example, almost everyone used to believe the earth was flat, that the universe was only four or five thousand years old, that women and slaves were inferior to adult males, and so on. These beliefs are now not held by most people. Perhaps we should be asking ourselves what beliefs we have today that in a century or two will be considered not worthy of belief.

In any case, epistemology is the study of how we know, what true knowledge is and what it is founded on, what the differences might be between knowledge, belief and opinion, and whether we can know anything at all with certitude.

The word “epistemology” derives from the Greek word episteme, knowledge. Epistemology is the ­ology, study of, what knowledge is and what it is grounded on. (The Greek word sophia means “wisdom,” and the word gnosis means “understanding,” as in the phrase gnothi seauton, “know thyself,” or better: “understand thyself.”) The word episteme refers to what we might call simple information, data, or “factual” knowledge. That is, it refers not to what we would call wisdom and not to what we would call deep understanding, but refers instead to knowledge of simple factual data. For example: How many stories tall is the Sears Tower? What biological functions does the kidney serve? What are the main differences between tropical and desert vegetations? What is the second law of thermodynamics? and so on.

So epistemology wants us to be continually questioning what we think we “know,” and wants us to be asking ourselves what our knowledge is founded on, etc.

For example, do you know what you ate for dinner yesterday? If you do know, what would you say that knowledge is based on? Perhaps you will say it is based on your direct experience of eating it, but the more accurate answer should probably be that your knowledge is based on a memory experience you are presently having, a memory experience which feels like it is an accurate memory of an experience you had yesterday. But can our memories ever be mistaken about something that happened yesterday? Is it possible for a person to have a false memory about something they believe happened in the past? Suppose you decide to trust your memory in this case, though. If you do, then what you are in effect doing is deciding to “believe” what your memory is telling you. So in effect your “knowledge” about yesterday’s dinner is based on a “belief” you choose to have about the accuracy of your present memory. Your belief about your memory’s accuracy may turn out to be mistaken in this case (you know your memory has been mistaken sometimes in the past when you originally thought that it was remembering correctly.) And yet, despite the fact that we all know memories can be mistaken even when they feel like they are being accurate, you are presently choosing to believe in the accuracy of your memory about yesterday’s dinner. How does a person decide when to trust their memory and when not to?

Now most people do not like the idea of trying to question everything they know or believe. The epistemologists understand this, but they also understand how important it is to try to find out what is actually, really true in the world. It is important in the sciences, in the study of history, in psychology and sociology, and even in daily events in the world. What really actually did happen between Clarence Thomas and Anita Hill, for example? How does the human immune system really work? How does the brain actually work? Do breast implants cause autoimmune diseases or not? Do pesticide residues cause cancers and neurological diseases? Will it be possible to make an effective HIV vaccine? And so on. We would rather know the actual truth about these things, and not have to rely only on opinions or beliefs.

Perhaps the most fruitful way to approach some of the epistemological questions we will be exploring this quarter will be to try questioning some of the beliefs that we never question, beliefs that we all have and hold because they seem so obvious to us. Let’s consider a few examples of these common beliefs.


Most people in the western world believe that time is real, that it is not a human construct, and that it actually exists out there in the world rather than just in our brains. As we will see when we discuss the work of Immanuel Kant (and others), there are some very important reasons to doubt whether this belief is true or not.

We’re Here

Most people believe that they are actually situated right where they think they are. You probably believe that you are actually sitting right there in the room and reading this text right now. You may have no doubts about that at all. And yet it is possible that that belief is completely wrong. It may be the case that you are not actually there right now at all, but are actually asleep in your bed and only dreaming that you are there. During a dream you are usually just as fully convinced that what you are experiencing is real as you are convinced right now that what you are experiencing is real. It is not always possible to distinguish between what is a dream and what is reality.

Or perhaps it may be the case that you are actually sitting in someone’s office right now and that you have just been hypnotized to believe that you are sitting at home reading. Anyone who has ever been hypnotized realizes how complete and real those illusion can be.

It may be the case, in other words, that what you take to be an obvious fact — viz., that you are sitting and reading in that room right now — may actually turn out to be only an illusion. You may not actually be where you think you are.

Stuff Exists

Most people believe that physical material things — what we will call “stuff” — actually exists. This seems to be one of our most cherished beliefs in the modern world, the belief in the real existence of physical matter. We moderns might truthfully be termed “materialists,” in the sense that we believe so dogmatically in the existence of physical matter.

This belief in the physical existence of material things is so deeply ingrained in us — it is even built into the very structure of many (but not all) languages — that it seems unquestionably obvious. We cannot imagine how anyone with any sense could even consider doubting that physical material things exist.

The belief in physical material stuff is a dogma with us. We hold this belief dogmatically and unquestioningly, and we consider it laughable and foolish that anyone would question it. (In much the same way the flatness of the earth seemed patently obvious to everyone a few centuries ago, and it was thought that only fools would question it.)

What does it mean to hold to a belief dogmatically? It means that we hold to it unquestioningly and we consider it foolish and wrong to doubt that belief. (Not all dogmas are religious ones, of course; many kinds of beliefs are held dogmatically and unquestioningly.) One indication that a belief is a dogmatic one for you is if you find it ludicrous that someone would ever question it, or if it makes you slightly irritated when someone seriously calls it into question. People do not like to have their dogmatic beliefs questioned.

What the epistemologists would want us to do is to be willing to examine and question all of our beliefs, especially the ones we most take for granted, and those to which we have become most strongly attached. Unless we are willing to question these beliefs, we will not ever make progress in our understanding of the world. It was important, for example, to question our dogmatic belief in the flatness of the earth, and also to question our dogmatic belief that the earth was the center of the universe. Without questioning even these most obvious beliefs, beliefs that virtually everyone held, we would never have made any progress in our understanding of the world.