What Is Gettier's Argument Against The Value Of Knowledge?

Edmond Gettier is considered to be one of, if not the most important philosopher of 20th Century philosophy. Gettier's argument against the traditional account of knowledge, aka "The Gettier Problem", is knowledge defined as justified true belief. The idea of justified true belief declares that in order for a given proposition to be true, one must believe more than the relevant true proposition, but also to have justification for doing so. Gettier argues that the traditional conditions for knowledge in the JTB (justified true belief) model are not sufficient. In other words, in some cases, meeting the 3 conditions, which are truth, belief and justification, are not enough to count something as knowledge. Gettier cases are counter-examples to the JTB model and they work against the account of knowledge. In order to validate his argument and challenge, Gettier refuted the original definition of knowledge while also sparking pronounced epistemological energy and innovation.
Since Gettier cases are based on situations in which a false belief is considered true by luck, all such cases would be excluded from the class of justified beliefs. One could make the justification and truth condition almost completely independent and hold that having a justified belief puts us in the best position available for getting the truth, but that this position isn’t very good and so most justified beliefs will be false. Gettier cases are meant to challenge our understanding of propositional knowledge.
An example of a Gettier case would be:
John and Bob have applied for a certain job. And John has strong evidence for the following:
1. Bob is the man who will get the job, and Bob has ten coins in his pocket.
John's evidence for premise (1) might be that the owner of the company assured him that Bob would be selected over him, and that John, had counted the coins in Bob's pocket ten minutes