Overview

Gettier problems are a set of thought experiments introduced by Edmund Gettier in 1963 that challenged the traditional definition of knowledge as Justified True Belief (JTB). They demonstrate cases where a person has a justified true belief that intuitively does not count as knowledge.

Core Idea

The core idea is that you can be right (True Belief) and have good reasons (Justified), but still only be right by luck. If luck is the primary reason for the truth of the belief, it isn’t knowledge.

Formal Definition

A Gettier case is a counterexample to the JTB analysis of knowledge. It involves a situation where:

  1. S believes that P.
  2. P is true.
  3. S is justified in believing that P.
  4. But S does not know that P (usually due to epistemic luck).

Intuition

Imagine you look at a clock that says 12:00. You believe it is 12:00. The clock is actually broken and stopped at 12:00 yesterday, but by coincidence, it happens to be exactly 12:00 right now.

  • You believe it is 12:00.
  • It is true that it is 12:00.
  • You are justified (clocks are usually reliable).
  • But do you know it is 12:00? Most say no, because you just got lucky.

Examples

  • The Job Applicant: Smith believes Jones will get the job and Jones has 10 coins in his pocket. Smith deduces “The man who will get the job has 10 coins in his pocket.” Turns out Smith gets the job, and Smith unknowingly has 10 coins in his pocket. The belief was true and justified, but not knowledge.
  • The Fake Barns: Henry drives through a county full of fake papier-mâché barns. He looks at the one real barn and thinks “That’s a barn.” He is right and justified (it looks like a barn), but given the context, he could easily have been wrong.

Common Misconceptions

  • Misconception: Gettier showed that knowledge is impossible.
    • Correction: He only showed that the JTB definition is insufficient, not that knowledge doesn’t exist.
  • Misconception: Any false belief is a Gettier case.
    • Correction: The belief must be true to be a Gettier case.
  • JTB Theory: The view that Knowledge = Justified True Belief.
  • Epistemic Luck: The element of chance that Gettier cases exploit.
  • Defeasibility Theory: An attempt to fix JTB by adding a “no defeaters” condition.
  • Causal Theory: An attempt to fix JTB by requiring a causal link between the fact and the belief.

Applications

  • Philosophy of Science: Understanding when a scientific theory is actually “known” versus just accidentally correct.
  • Legal Theory: Distinguishing between a lucky guess and proof beyond reasonable doubt.

Criticism and Limitations

  • The “So What?” Response: Some argue that the concept of knowledge is loose and Gettier cases are just edge cases that don’t matter for practical purposes.
  • Experimental Philosophy: Studies show that laypeople’s intuitions about Gettier cases vary across cultures, challenging their universality.

Further Reading

  • Is Justified True Belief Knowledge? by Edmund Gettier (the original 3-page paper)
  • The Analysis of Knowledge by Robert Shope
  • Knowledge and its Limits by Timothy Williamson