The philosopher Edward Gettier formulated a type of problem to show that the definition of knowledge 'Justified True Belief' (=JTB) is not necessarily true. It is said to be true, when the next three conditions are met:
'Justified True Knowledge' is about the momentum of the believer validating its premises and finding out what 'really' happened. Gettier is showing that JTB is not valid, because one can have accidently a good conclusion based on false premises, which by unforeseen circumstances turn out to be right.
If the believer in his situations would ask about his premises, they would tell things, which were wrong premises in the situation, nevertheless reasonable. So, they thought they had good reasons to believe it, but actually they had not. His real challenge to the theory of knowledge is 'can we truly know at any given moment?' He doubts it.
The possibility that one can draw rightful conclusions based on unknowingly false assumptions is the reason that Edward Gettier doubted JTB being a solid definition of knowledge. I have several problems concerning the added value of his doubts:
ad 1 JTB dates back to Plato and is an intuitive theory of knowledge. It is used on a daily basis. It is a theory of knowledge from the perspective of the subject. A simple example is that two people are playing dice. The first player throws a dice using a cup and says, although the cup is still covering the dice, "I have thrown a six." The other player answers "Yeah right, I bet you didn't. Lift that cup and we will see." The second player is applying JTB properly. The statement of the first player is a belief, which can be true or false. It is already true or false as the dice is thrown. Yet it is unknown since the cup is preventing it to be seen. The second player challenges the first player and asks for the proper form of justification to evaluate the claim. Which is lifting up the cup so both can see. If that is done, then will it be known if the statement of the first player was a justified true belief.
JTB is a strange set of conditions, how intuitive it may be. The reason is that there is a belief involved and something that is true. In my opinion do these two realms exclude each other. A belief is personal, belonging to the subject. A true statement does not belong to the subject. A subject can have beliefs that are equal to true statements, but beliefs are not restricted to that. Beliefs can exist in fields of life where truth does not play any part, for instance relationships. "She is the most beautiful woman on earth" is a firm belief, shared by a lot of men. But not referring to the same woman. And they all are right in their belief.
Statements that can evaluate to true or false must get evaluated to a single value. They require justification. Beliefs do not require justification and when they do, their justification is good when the subject decides it is good. There is ultimately no other criterium than the stamp 'good'. People can create a whole building of conditions based on what they might justify some belief, but it is their personal choice which conditions are required. It is very common that two people in the same situation with different set of beliefs will perceive the situation differently. I only have to write down the word 'politics' and probably a lot of examples will come to your mind. A truth does not require a justification. It is. Personal beliefs and knowledge are therefore mutually exclusive.
The truth value of JTB is in my opinion therefore not very clear. It works good in simple cases, but the moment situations get more complicated, then will it already get very fuzzy. Which is what we see throughout history. How many times have people come to the conclusion that they were tired of the war? Yet, many new wars have started since. I think it is a true statement that people will eventually get tired of the war in which they are engaged. However, there are a lot of people in history thinking that they were going to fight a justified war.
The truth value of a lot of knowledge can change overtime. There were centuries in which slavery was considered normal. Nowadays it is called - very very justifiable in my opinion - a violation of human rights. What is the truth value of those statements? What are the proper justifications?
There are a lot of different fields of knowledge. Some have relatively straightforward models of justification, like mathematics, physics or accountancy, other realms of knowledge, like philosophy, human relations or religion, have only swamps of justification at their disposal. The truth value of JTB varies with the possible methods of justification and is, although an intuitive theory of knowledge, in the most important fields of knowledge hardly applicable.
ad 2 Gettier describes situations in which the believer could not perceive or know well and because of that came falsely to the right conclusions. He uses a priori unknown circumstances. One wonders if that is decisive to refute JTB. That you might have good reasons to have some belief, but later on has to change it, is reasonable behavior. Is that not exactly what JTB is all about? He is treating JTB like one can never change his own believes or must come in one attempt to the eternal truth. But I think in essence JTB has a big freedom of mind. I think it is at the core of this philosophy of knowledge. Knowledge in JTB (truth) is never proven really, but always to be believed in. When you would say that knowledge is ultimately that which is true, then leave JTB all behind please. Then you do not need any statement about believes/ being sure/ accepting. JTB states that truth is what you believe, what you sincerely believe that is true. How do you establish this truth? To have good reasons why you believe that which you say is true. And so on until eternity. To discredit JTB 'because it might produce justified true knowledge but no real knowledge' is to say that JTB is there to lead the way to certain knowledge. It is not. To demand from JTB that it produces knowledge as truth, is like asking a donkey to be a horse. It might look like it, but it just isn't.
Science, for instance, is an endeavour based on the assumption that we grow towards truth. With the development of scientifical knowledge we expect that slow by slow we come closer to the truth. That means basically that the third premise 'having good reasons to believe' is considered to improve in time. Newton did a very good job, but based on his work can no cell phone get produced. Understanding of quantum physics is required to make cell phones. Gettier has created his own examples, but he could have used well established examples from science. The orbit of Mercury has been a problem to explain until the understanding of quantum physics developed. It was therefore well known that the laws of Newton and Keppler were accurate, yet insufficient. Exactly the situation Gettier was trying to reveal with his examples. The history of science is full of those kind of examples and the scientifical community is proud of it. It shows that science developes and continues to build upon earlier JTB's. That is the whole process of scientific progress.
Every process in knowledge, from the first years at school to wisdom, starts with the premise that knowledge will gradually evolve and get better in life. That is called experience. It is not a problem of JTB. It is a problem of life. The person might stay the same over all those years, he might have the same feeling in life, yet he might believe totally different things as he is evolving in life. What was true is not true anymore. What he believed once firmly, he does not believe anymore. What he once saw as a justification, does not count anymore for him. What he first described as the situation has changed. This is a very natural process. Moral development for instance influences what a child or grown up perceives as the situation or as what is true or not. The same situation, the same person in different years and everything can be perceived differently. In a lot of situations is knowledge a big issue and a very big challenge. Or it might not even exist, like the answer to the question 'is there a possibility to start a justified war?' A lot of knowledge was never, is not and will never be justifiable knowledge. We, as humanity, have believed a lot of things based on the wrong reasons, but we believed that it was true. Some of those beliefs are still standing strong, other beliefs have faded away in history. There are so many impressive examples of once hold beliefs that are now perceived as utterly wrong, why did philosophers need an article with two fabricated crippled examples to realize this?
ad 3 Let's take a look at the next situation:
A: elephants are invisible in strawberry fields, when they wear little red socks.
B: yeah, right.
A: have you ever seen elephants in strawberry fields?
A: you see?
This is a type of statement one can never deny as untrue as long as it is not proven in reality. But nobody will try to disprove it in reality as it will never have the priority to test it. No one will believe it, although no one will take the proof of the pudding. If you would try to test it, then it would show very difficult, as you only might prove that you do not have the proper type of litte red socks to make elephants invisible in strawberry fields. Person A is believing something which nobody else will believe, person B has a point of view that is shared by the vast majority of humanity. Yet this is a bigger problem for the theory of knowledge. Not that it is a problem if someone might think that elephants can be hidden in a strawberry field using little red socks, but it is about believing/ being sure of/ accepting false statements as true and justifying those believes firmly. This is a huge problem in society and mankind.
This problem has many aspects, like freedom of speech and thought, but it also shows the strong force believing can be. In my worldview evolution has a tremendous pile of evidence. Even if not all questions concerning evolution are solved, one of them being the puzzling fact that a multiple changes in bodies have to occur simultaneously in order to work properly, there are so many facts coming from different fields of science which all prove evolution, that it can lead only to one conclusion. Yet millions of people that have access to more than enough information do not belief in evolution. How is that possible? How can they think that elephants can become invisible in strawberry fields wearing litte red socks? That is for me the real challenge about any theory of knowledge. When can we say that it is a belief and when that it is knowledge? How can we preserve freedom of speech and thought, even if that implies that people say things that are completely false? We all know the danger of forcing people to think within some restricted box, but we also know the dangers of letting people think outside any box - some of the latter people are those who force other people to think within their line of thought. What is the difference between knowledge and belief? When is something true in complicated affairs? Might something like fact checking limit freedom of speech? Could such a limitation be applied to public functions but not to individual people? If there is no reason or argument to call something knowledge instead of belief, should we then not abolish the use of the word knowledge altogether? Is that the moment elephants wearing little red socks get invisible in strawberry fields?