Plato defined knowledge as “Justified true belief.” This definition went virtually unchallenged until the 1960’s when Gettier proposed that all three conditions could be meet without yielding knowledge. Let us look at a “Gettier” type example.

Suppose Mr. Chen is watching the world’s cup this year, 2020. Just like last year, the same two teams are in the championship–Denmark and New Zealand. The game is much the same as it was last year, same players, same scoring, etc. Last year Denmark won the championship in the last 5 seconds as its star player kicked a winning goal. Mr. Chen is watching with intensity. However, unbeknownst to him, the cable station / internet service makes an error. In the last 5 seconds of this year (2020), they replay the last 5 seconds of last year’s championship game (2019). As it so happens, in reality (–in 2020–), Denmark did in fact win the championship in the last 5 seconds of the game as its star player (–the same person as last year–) kicked a winning goal. The station immediately switches back to this year’s broadcast. But Mr. Chen only saw the 2019 footage, which is virtually identical to that of 2020.

Now, consider the following:

1. Mr. Chen has a belief that Denmark won the world cup in 2020.

2. It is true that Denmark won the world cup in 2020.

3. Mr. Chen is justified in his belief because he “saw” the winning goal being kicked by the star player. (When he says things like, “Wow, the star player just won the game,” it is true.)

On the face of it, Mr. Chen seems to meet the criteria for knowledge as Plato set the terms. Conditions (1)-(3) seem to be met.

However, do you think that Mr. Chen really knows that Denmark won? Does he really have knowledge??? Remember, he saw the last 5 seconds from 2019, not 2020. It seems as though he has a true belief and it seems to be justified, yet it does not seem to be knowledge.

This is the infamous “Gettier problem: Someone can have a justified true belief without it being knowledge.

Is Gettier correct?? From the year of publication, 1963 into the 1990’s thousands of articles were written by professional philosophers to analyze these types of examples.