Philosophy
Gettier Problems and the Analysis of Knowledge
Quick fact
Edmund Gettier's 1963 paper, 'Is Justified True Belief Knowledge?', is just three pages long yet has generated thousands of books and articles in response, making it one of the most influential philosophy papers of the 20th century.
Why this is interesting
Imagine you're absolutely certain of something, and you're right—but you're only right by pure luck. Do you actually know it? This is the strange puzzle Gettier introduced.
Read the full explanation
Understanding Gettier Problems and the Analysis of Knowledge
For centuries, philosophers defined knowledge as justified true belief (JTB). This means you know something when: (1) you believe it, (2) it is true, and (3) you have good reasons for it. But Gettier showed that even with all three conditions, you might still not have knowledge. He created clever counterexamples where each condition holds, yet the truth of the belief is a matter of chance. Your justification is solid, but it doesn't connect to the truth in the right way. Think of it like a broken clock that happens to show the correct time twice a day: your belief is true, but not because your reasoning was sound. The Gettier problem forces us to ask whether there is any definition of knowledge that can avoid such lucky accidents.
A deeper explanation
Gettier's counterexamples work by exploiting a gap between evidence and truth. In the classic Smith/Jones case, Smith has strong evidence that Jones will get the job and that Jones has ten coins in his pocket. From this, Smith deduces that 'the person who gets the job has ten coins in his pocket.' It turns out Smith gets the job, and Smith himself has ten coins. So his belief is true and justified, but intuitively he doesn't know it because the truth is accidental. The underlying issue is that justification can be based on a false premise (that Jones would get the job) even if the conclusion happens to be true. Over the years, philosophers have proposed various extra conditions to rule out this kind of luck, such as adding a fourth condition that the belief must not rely on a false lemma, or requiring that the belief be reliably formed (reliabilism). But each attempt encounters new counterexamples, leading to a rich and ongoing debate about the nature of knowledge. The Gettier problem thus reveals that knowledge is not just a matter of having good reasons; it also requires a reliable connection between belief and truth that excludes luck.