Justified True Belief

• Plato argued that knowledge is "true belief accompanied by a rational account"

  
  

  Plato argues that for something to be considered knowledge, it has to meet 3 conditions

  • Belief - You must believe it
  • Truth - It must be true
  • Justification - You must have good reasons or evidence to believe it

  "Justified," "true" and "belief" are all necessary for knowledge
• Examples:

  • You can't KNOW something is true if it ISN'T true.
  • If someone said "the moon is made of cheese," this would not count as knowledge because it is NOT TRUE

  
  

  • Similarly, you can't KNOW something that you don't believe
  • It doesn't make sense to say that "I know today is Monday but I don't believe today is Monday"

  
  

  • You have to have justification for your belief, it can't be a guess
  • You don't know something if you guessed it

  
• Justified True Belief - Examples

  
  

  Justified:

  • If you believe the Earth revolves around the Sun based on scientific evidence (like observing the sky), this belief is justified.
  • But if you believe it just because someone told you, it may not be well-justified

  True:

  • If you believe the Earth is flat, that’s a belief, but it’s not knowledge because it’s not true

  Belief:

  • If you don’t believe that the Earth revolves around the Sun, you can’t say you know that the Earth revolves around the Sun, even if it’s true.
• JUSTIFICATION:

  • Suppose someone asks you if you know how many moons Pluto has.
  • You have no interest in astronomy but just have a strong feeling about the number 5 because it’s your lucky number or whatever.
  • You’d be right – Pluto does indeed have 5 moons – but it seems a bit of a stretch to say you knew Pluto has 5 moons.
  • Your true belief “Pluto has 5 moons” is not properly justified and so would NOT count as knowledge.
• Problems with JTB: Edmund Gettier

  
  

  Gettier's paper describes two scenarios where an individual has a "Justified True Belief" that is NOT knowledge

  
  

  Both scenarios involve a belief that does not count as knowledge because the belief is only true due to LUCK

  • So, in both scenarios, there is a belief and that belief is only TRUE because of luck
• Gettier Case 1 - Smith and Jones

  • Smith's belief that "the man who will get the job has 10 coins in his pocket" follows JTB, there is a belief, it is justified and it is true
  • Justified: He hears the interviewer say Jones will get the job and sees that Jones has 10 coins in his pocket
  • True: The man who got the job (Smith) did in fact have 10 coins in his pocket
  • But we do NOT want to say this counts as knowledge because it's LUCK that led Smith to being correct
  • This shows that the Tripartite Definition is not sufficient, YOU CAN HAVE JTB THAT IS NOT KNOWLEDGE

  
• Gettier Case 1 - Smith and Jones

  
  

  • Smith's belief that "the man who has 10 coins in his pocket will get the job" is justified, it's true and it is a belief
  • But we do not want to say it counts as knowledge.
  • This shows that Plato's Tripartite Definition of knowledge is NOT SUFFICIENT because you can have a Justified-True-Belief that is NOT knowledge
• Gettier Case 2 - Jones' Ford and Brown in Barcelona, Disjunction Introduction

  
  

  Gettier’s second example relies on the logical principle of disjunction introduction (or, more simply, addition).

  
  

  Disjunction introduction says that if you have a true statement and add “or some other statement” then the full statement (i.e. “true statement or some other statement”) is also true.

  
• Gettier's 2nd example relies on "Disjunction Introduction"

  • True: “Either Jones owns a Ford or Brown is in Barcelona” turns out to be true.
  • But Smith thought it was true because of the first condition (Jones owns a Ford) whereas it turns out it is true because of the second condition (Brown is in Barcelona)
  • Justified: “Jones owns a Ford” is justified, and this means that the second belief “Either Jones owns a Ford or Brown is in Barcelona” is also justified.

  It's JTB, but it's wrong to say that it counts as knowledge, because it was LUCK that led him to being correct
• Flaws with JTB

  Flaw with "Justification":

  • Children and animals have knowledge, but they can't justify it, so the Tripartite System potentially says that CHILDREN AND ANIMALS DON'T HAVE KNOWLEDGE!

  Flaw with "Belief":

  • There are scenarios where someone may know something but FORGOTTEN IT. You don't know that you know it!

  Gettier Problems also prove that JTB is not sufficient to define knowledge