What is epistemology? It is the branch of philosophy concerned with the theory of knowledge. Epistemology studies the nature of knowledge, justification, and the rationality of belief. Much of the debate in epistemology centers on these areas:

(1) the philosophical analysis of the nature of knowledge and how it relates to such concepts as truth, belief, and justification,

(2) various problems of skepticism,

(3) the sources and scope of knowledge and justified belief, and

(4) the criteria for knowledge and justification. (*Wikipedia)


EXERCISE 1: Belief, opinion or knowledge:

1- You burned, because the handle was metallic and conducts the heat.

2- Do not ask me why, but I’m sure she’ll come.

3- I know water is made up of hydrogen and oxygen.

4- Do not be angry, I just said that I think he will not win again.

5- I have the impression that this will be a good year.

EXERCISE 2: Belief, opinion or knowledge.

1) Marcos thinks that this year Valencia C.F. will win the league.
2) Columbus thought the Earth was round.
3) Felipe knows that his work is underpaid.
4) Scientists know the reasons and can explain why climate change is happening.
5) John knows how to ride a bike.
6) I think John will go to the party, but I am not sure.


*By Varughese John:


Before we understand how we know what we know we can begin by distinguishing between opinion, belief and knowledge—all of which seem to indicate a certain way we hold an idea or a belief. An easy way to distinguish between them is to compare them on a grid against 2 variables: a) whether it is subjective or objective and b) on the sense of certitude.

  Objective/subjective Sense of Certitude
Opinion Subjective Low
Belief Subjective High
Knowledge Objective High

1/ Opinions are generally held loosely with a low sense of certitude. They are also subjectively held and need not be shared by others. They could be about preferences for a certain type of music, or tastes pertaining to food, or views about politics or a particular sport. It would really be silly to argue against my friend’s opinion that the best paellas are made in Vera. And even if I were to argue that the best ones are made in Águilas, our positions merely indicate what our preferences are rather than the “truth” about it.


2/ Beliefs, on the other hand, are subjective (in that they are primarily held by an individual and are not verified by any objective method of verification), nevertheless they are high on the sense of certitude. It is important to remember that certitude does not mean infallibility; rather it merely indicates how sure one feels about one’s beliefs. Of course, someone could also hold a ‘belief’ loosely. But we shall retain the term opinion for such, irrespective of what is held—be it something as insignificant as a preference for certain food or something as significant as an article of religious faith. A belief, therefore, would be characterized by something stronger, and in some cases, it could be so strong that we may call it conviction. Despite how significant it may be for someone, a belief has nothing in itself that makes it necessarily true—neither the sense of certitude accompanying a belief nor the total sincerity with which a belief is held can assure the truth of the belief.

3/ Unlike opinion or belief, Knowledge, especially propositional knowledge (we aren’t talking about knowledge in the sense of an ability or a skill but a statement or an affirmation that is either true or false) is a belief that can be verified and understandably carries with it a high sense of certitude. In fact, a classical account of knowledge defines it as “justified true belief.” By that definition, knowledge has to fulfil the criteria:

  1. a) of being a belief,
  2. b) of being true, and
  3. c) of being justified.

However, what constitutes as justification of a belief in order for it to be considered knowledge? There are many ways in which one can justify a belief. I can do so on the basis of evidence of my senses, as in, “I see that the car is red and therefore I know it is red” or appeal to reason, as in, the statement that “‘this is a car’ and ‘this is not a car’ cannot both be true at the same time in the same sense” or appeal to an authoritative testimony (a real authority, not a false authority as we studied in relation to fallacies). So then, we find justification for our beliefs in all manner of ways.

Knowledge, by definition is true and there cannot be false knowledge. Knowledge also requires that one believes it. However, there may be cases where we revise what was thought to be knowledge. Normally, when there is a revision of what once was falsely considered knowledge, we merely state that we once believed it as “x” but now we know it as “y”. That is, despite the objective nature of knowledge and the sense of certitude accompanying it, it need not be infallible.


Knowledge should account for more than merely obtaining a true belief. That is, if true knowledge is arrived at accidentally or merely by luck, it poses problems to a knowledge claim. In 1963, Edmund Gettier raised this problem in his short paper. He presented several cases where one held a justified belief, yet the belief was true purely by chance. For example: Let us imagine that you walk towards the SAIACS lawn early on a misty November morning when you see a great number of egrets sitting on the lawn. You have counted 35 of them. However, in the way you counted, you really missed one egret but nevertheless got the number right since you mistakenly counted a white cloth lying in the distance as an egret. This seems to suggest that knowledge cannot just be ‘justified true belief’.

*You can read the text here:

EXERCISE 3: How will you respond to the Gettier problem? (Maybe… introducing a fourth condition or criterion?)