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The Gettier Problem: Disproving Plato's Theory of Knowledge

Updated on August 30, 2011

In ancient times, Plato developed a theory on knowledge which claimed that knowledge is made up of justified true belief. (For an in-depth explanation of Plato's Theory see the article Plato on Knowledge). Plato's argument was generally accepted by the philosophic community until 1963, when Edmund Gettier came on the scene. In his paper "Is Justified True Belief Knowledge" Gettier exposed a fundamental flaw in Plato's logic. Gettier created a hypothetical situation in which justified true belief fails to lead to knowledge, leading to the presumption that some other element would need to be present in order to facilitate knowledge. While Gettier used the now-famous example of "Smith, Jones and the Ford car," other philosophers have invented similar situations with have come to be known as "Gettier Problems."

Is justified true belief really equal to knowledge?
Is justified true belief really equal to knowledge?

Gettier Problem: Smith, Jones and the Ford Car

Smith believes that his neighbor Jones owns a Ford. Smith has regularly seen Jones pulling out of his garage in the Ford on the way to work for over a year. Thus Smith is justified in believing that Jones owns a Ford.

One weekend Smith, not knowing where his friend Brown is, states "Either Jones owns a Ford or Brown is in Barcelona" (Statement A). Unknown to Smith, Jones sold his Ford after work on Friday, and does not currently own a car. In addition, Brown actually is in Barcelona, but has not shared this information with Smith.

In this example Smith does indeed believe that Statement A is true, and is justified in his belief. Furthermore, Statement A is actually true, though not for the reason that Smith believes it is. Although all of Plato's requirements for knowledge are present (justified true belief), Smith does not possess the knowledge that Brown is in Barcelona and Jones does not own a Ford. Smith has justified true belief about his statement, but is lacking the essential knowledge that proves it as true.

Accidental Circumstance

Through a case of accidental circumstance, the truth that Smith imagined in his idea of the scenario, that Jones owned a Ford, was not actually true. Rather than this falsity negating the proposition (Statement A), the accidental circumstance has allowed for another version of truth to replace Smith's version.

The problem is that what Smith is referring to, the facts in question, are incorrect. Smith is being led by inaccurate premises, namely the idea that Jones owns a Ford, towards a true conclusion.

Elements of a Gettier Problem

In a Gettier problem, an individual is led to a true conclusion by premises that they believe to be true, but actually happen to be false. In addition, a set of circumstances exists that are similar enough to the individual's premise to uphold the element of truth, though the individual in question is unaware of these other circumstances.

In short, multiple conditions exist which could fulfill the requirement for truth. The individual whose knowledge is in question is only aware of a condition that does not satisfy the truth requirement.

While Gettier accepts Plato's position that justified true belief need to be present in order to have knowledge, he believes that a missing variable is necessary in order to account for the cases of accidental circumstance creating justified true belief without knowledge, as seen in the Gettier problem.


Submit a Comment
  • JohnsonKelenAngel profile image


    20 months ago

    Thank you. Belief is not knowledge :)

  • Silver Poet profile image

    Silver Poet 

    7 years ago from the computer of a midwestern American writer

    I love those kinds of puzzles. You've made learning this idea enjoyable and easy. Thank you!

  • Anaya M. Baker profile imageAUTHOR

    Anaya M. Baker 

    7 years ago from North Carolina

    Lol:) Thanks for the great comments!

  • Tom Koecke profile image

    Tom Koecke 

    7 years ago from Tacoma, Washington

    I'm not sure we can conclude concretely that multiple choice tests are effective barometers of learning. It would help me if you would give me my choice of answers so I could guess. Then you could tell me if I was correct!

    Thanks for the Hub. I like intellectual challenges!

  • Anaya M. Baker profile imageAUTHOR

    Anaya M. Baker 

    7 years ago from North Carolina

    Ah, so besides scratching our collective heads at philosophers that like to run around in circles, I think we can concretely take away the conclusion that multiple choice tests are not effective barometers of learning. It seems philosophy for once does have a practical purpose:) Thanks for the comment Tom, and I really enjoyed your analogy...

  • Tom Koecke profile image

    Tom Koecke 

    7 years ago from Tacoma, Washington

    I question whether Gettier created a problem that strikes a missing element in Plato's theory of knowledge.

    Smith's statement is true, he believes it to be correct, and he may be justified in believing so. However, Smith believes his true statement that Brown is in Barcelona is correct because he sees Jones backing his Ford out of his garage each morning. Therefore, he does not believe that Brown is in Barcelona, but believes Jones owns a Ford, which he does not. He just happened to make a statement that was correct because of extraordinary circumstances.

    It would be similar to two students taking math tests. Both tests have the same question on it. Both students get the answer correct. However, one test required the math to be done, while the other was multiple choice. The student who had to work the problem knows the answer. The student with multiple choices may have worked the problem and marked the correct answer, or may have guessed correctly. If it were the former, the student has knowledge. If it were the latter, the student has luck.

    Smith is lucky, not knowledgable.

  • jackie_fish profile image


    7 years ago

    really nice argument I enjoyed it reading it and it will help me my own hubs

  • Cagsil profile image


    7 years ago from USA or America

    An interesting hub. I've never been one for examining philosophers, nor have I ever been a student of any philosophical course. Therefore, I am not going to speculate on such things. I did find your hub quite interesting as I said and did manage to learn something I did not know. Thank you for teaching me something new. :)

  • Anaya M. Baker profile imageAUTHOR

    Anaya M. Baker 

    7 years ago from North Carolina

    Hee hee :)

  • dahoglund profile image

    Don A. Hoglund 

    7 years ago from Wisconsin Rapids

    It does seem that he only conclusion Smith can come to asa true is that Jones drives a Ford.

  • mckbirdbks profile image


    7 years ago from Emerald Wells, Just off the crossroads,Texas

    Gettier has Plato at a disadvantage. Plato's missing variable is a Ford.


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