The definition of knowledge is a concept that can be traced back to thousands of years ago. 

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Plato, author of Thaetetus (source)

The philosopher Plato wrote a famous dialogue around 369 BC. It was entitled Theaetetus, and it discussed the nature knowledge. It is in this piece of writing, that the philosopher introduces the Justified True Belief (JTB) Theory. This theory, as can be expected, revolves around the idea that knowledge is justified true belief and that knowledge can only really be considered knowledge if all JTB clauses are true. These clauses are (let’s call a belief x); 

  1. I believe X to be true 
  2. I am justified in believing that X is true
  3. X is true.

(The three clauses above are the official statement of the JTB theory)

In a more technical explanation, the JTB theory fundamentally divides knowledge in three different categories. Firstly: The belief, basically stating that knowledge requires a degree of certainty. Secondly: The justification, meaning that this belief needs to be proven with some evidence to it. Thirdly: the truth, being that the belief must in the end, correspond the the complete truth.

The JTB Theory seems correct. It applies to a lot of cases. Now, Let’s use a real life example to test it out.

Let us consider Albert Einstein’s Theory of Special Relativity. It states that;

“the laws of physics are the same for all non-accelerating observers, and the speed of light within a vacuum is the same no matter the speed at which an observer travels.” (source)

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Albert Einstein (source)

So let’s break this down and apply to it to the JTB Theory. First things first, we have to identify a belief. Einstein clearly believes that “the speed of light within a vacuum is the same no matter the speed at which an observer travels.” Lets call that his belief. It is important to note that we can not consider it knowledge yet as for our terms and purposes, it is still a belief. 

Let’s now analyze the second clause of the JTB theory that being, I am justified in believing that X is true.

Albert Einstein shows that his belief is actually justified, due to his years of studies, which led him to form his famous equation of mass-energy equivalence, E = mc2.

Now, going to the last part of the JTB theory, which is, X is true.

Einstein’s initial belief, which he pondered to be true was in unbeatably, the truth. By being proven by the mass-energy equivalence, we can conclude that this belief was justified, and since it was justified, it has to be true. Since this belief followed all the criterium of the JTB theory, it is also knowledge, given that in the JTB theory, knowledge is justified true belief

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JTB Theory Tripartite Diagram (source)

This is perfect. We were able to understand what the JTB Theory is exactly, where it came from, and were able to use a real life example to prove it. It is flawless.

Or is it…?

Now, what if the JTB Theory was flawed? What if there were cases in which it didn’t apply? What if there were cases in which it was just plain out wrong?

Such cases do exist. They are called Geitter Problems, and they are the next concept we will be looking at.