Epistemology

Epistemology is the investigation of knowledge and rational belief

Contents

Analysis of Knowledge

  • In the dialogue Theaetetus, Socrates (speaking for Plato) asks what knowledge is. Plato was asking about propositional knowledge, knowledge that something is the case, versus knowing how or why or knowing a person.
  • The easy answer to Plato’s question is: “knowing that” means being aware. Thus, knowing that tariffs are taxes means being aware that tariffs are taxes.
  • But Plato had something more in mind. He wanted to analyze the concept of propositional knowledge into its components.
  • Two components of propositional knowledge, Plato found, are truth and belief. That is:
    • Person S knows that P logically entails P is true.
      • For example you can’t know that George Washington was the first president without Washington actually being the first president.
    • Person S knows that P logically entails that S believes P.
      • You can’t know that George Washington was the first president without believing he was, without accepting it as true.
  • Thus
    • Person S knows that P logically entails that P is true and S believes that P.
  • Plato noted that the reverse is not true, that the following is false:
    • P is true and S believes that P logically entails that S knows that P.
  • As Socrates points out:
    • Suppose a jury has been justly persuaded of some matter which only an eye-witness could know, and which cannot otherwise be known; suppose they come to their decision based on hearsay, forming a true belief: then they have decided the case without knowledge.
  • A person can correctly believe that McKinsey is the perpetrator but not know it, since their belief is based on rumor or hearsay.
  • Thus knowledge is true belief plus something else. Socrates’ example suggest that the something else is evidence.
  • The idea is that:
    • Person S knows that P is logically equivalent to (1) P is true, (2) S believes that P, and (3) S has evidence that justifies the belief that P
  • Thus, knowledge is justified true belief.
  • Or so contemporary philosophers thought.
  • In 1963 Edmund Gettier published a 3-page paper setting forth two counterexamples to the JTB analysis, which led to the publication of hundreds of papers trying to fix the JTB analysis and presenting different kinds of additional “Gettier” counterexamples.
  • The basic idea of the Gettier counterexamples is that a person is justified in believing something that’s true only by chance and therefore doesn’t have knowledge.
  • A typical Gettier counterexample:
    • I see what appears to be my friend Tom stealing a book in the local bookstore. I know what Tom looks like and it’s clear that he’s stealing the book. So I’m justified in believing that Tom stole the book. But it was actually Tom’s identical twin I saw, someone I was not aware of. The kicker is that Tom was also in the bookstore stealing a book. So I was justified in believing that Tom stole a book since the person I saw looked exactly like Tom. Moreover it was true that Tom stole a book, since indeed he was, though I didn’t see him. But I didn’t know Tom stole a book, since my belief was true only by chance.
  • Numerous attempts have been made to fix the JTB analysis by adding a fourth condition.
    All have failed.
  • A view I favor is that the analysis fails because justified belief isn’t strong enough for knowledge. What’s needed is certainty.
  • Here’s an argument (by John Tienson) that, no matter how strong the evidence, justified belief isn’t adequate for knowledge:
    • Suppose a detective investigating embezzlement has overwhelming evidence justifying his belief that Mr. Black is not the embezzler. And he has the same overwhelming evidence that Mr. White is not the embezzler. It turns out that Black is the embezzler. So the detective didn’t know that Black was innocent, since he wasn’t. But then the detective neither knows that White is innocent (even though he is) because his evidence is exactly the same.
  • My take on Tienson’s example is that the detective didn’t know that White is innocent because, even given his overwhelming evidence, he could have been mistaken, since he was in fact mistaken about White.
  • I suggest that:
    • Person S knows that P is logically equivalent to (1) P is true, (2) S believes that P, and (3) P is certain for S based on his evidence.
  • In the Gettier counterexamples the subject doesn’t have knowledge because he could have been mistaken.
    • That’s why I don’t know that Tom stole the book.
    • That’s why the detective doesn’t know that White is innocent.