What is the difference between knowledge and justified true belief after Gettier?

The difference between knowledge and justified true belief after Gettier revolves around the inadequacy of the traditional tripartite analysis of knowledge, which states that for someone to know a proposition, it must be (1) a belief, (2) true, and (3) justified. Edmund Gettier's 1963 paper presented counterexamples demonstrating that one can have a justified true belief that nevertheless fails to qualify as knowledge due to certain failures in the justification's relationship to the truth of the belief.

Gettier's examples show that justification can involve reasoning from false premises, resulting in a belief that is true merely by chance. For instance, in one of Gettier's scenarios, a character named Smith has strong justification for believing that Jones will get the job based on misleading evidence. He concludes that whoever gets the job has ten coins in their pocket, which turns out to be true, but not for the reasons he justified his belief; Smith himself happens to be the one with ten coins. Thus, even though Smith has a justified true belief, he does not 'know' it because that justification is based on falsehoods within the reasoning process^[1].

This indicates that while justified true belief might satisfy some conditions for knowledge, those conditions are not jointly sufficient, necessitating the search for additional criteria that would exclude Gettier cases. Many epistemologists now attempt to define knowledge through additional conditions to sidestep the problems highlighted by Gettier, such as requiring that justification not stem from false beliefs or ensuring a certain degree of reliability in the justification chain^[3][5].

In summary, the crux of the differences lies in recognizing that not all justified true beliefs qualify as knowledge, primarily due to the nature of their justification and its relation to the truth.