The Gettier Problem and the Definition of Knowledge

Author: Andrew Chapman
Category: Epistemology
Word Count: 1000

1. The Traditional Analysis of Knowledge

What is knowledge?1 To get clear on the notion of knowledge, many philosophers have proposed that we provide an analysis of the concept of knowledge. To provide such an analysis would be to lay out and explain each of the components of that concept. The thought is that the individual conceptual components will be individually necessary (each one of them required) and jointly sufficient (all of them together enough) for the concept under analysis.2

Since the time of Plato’s dialogue Theaetetus, a near-universally accepted analysis of the concept of knowledge, what we can call the traditional analysis of knowledge, was that knowledge was (i) justified (ii) true (iii) belief. First, the thought is that a person must believe something to in order to know it. It would seem contradictory to claim that Max knows, but that Max doesn’t believe, that his tennis racquet is in the closet.

Second, it would seem contradictory to claim to Max knows that his tennis racquet is in the closet while his racquet is actually back at the court. Max might believe that his racquet is in the closet and be wrong. He might believe that he knows that his racquet is in the closet and be wrong. He might even have good evidence that his racquet is in the closet and nonetheless be wrong. In none of these cases would we say that Max knows where his racquet is, since what he believes is false.

Finally, it seems as though Max needs some justification, evidence, or good reason to believe that his racquet is in the closet in order for him to know that it is.3 Suppose that Max has no good reason to believe that his racquet is in the closet. If Max just guesses that it’s in the closet, even if he serendipitously gets things right, it seems as though Max, while having a true belief, has an unjustified true belief, and hence, does not have knowledge.4

Edmund Gettier.
Edmund Gettier.

2. The Problem

Edmund Gettier’s 1963 paper, “Is Justified True Belief Knowledge?,” presented a serious challenge to the traditional analysis. A conceptual analysis can be rebutted by providing apparent instances of the concept that do not meet the analysis (challenging the necessity of the analysis) or by providing concepts that apparently conform to the analysis that are nonetheless not examples of the concept under analysis (challenging the sufficiency of the analysis).

In Gettier’s paper, he provides two structurally similar examples of the latter sort—he gives two cases of apparent instances justified true belief that nonetheless don’t appear to be instances of knowledge. Let’s look at the more famous of the two.

Smith and Jones have both applied for a job. The president of the company tells Smith that Jones, and not Smith, will get the job. Further, Smith has just counted all of the coins in Jones’s pocket—there are ten coins in Jones’s pocket. Smith seems to have excellent evidence to believe that Jones will get the job and Jones has ten coins in his pocket. From this, Smith infers, and subsequently believes, that the man who will get the job has ten coins in his pocket. However, unbeknownst to Smith, he too has ten coins in his pocket and further, a last-minute judgment changes the decision regarding who gets the job from Jones to Smith. So it is true that the man who will get the job has ten coins in his pocket, since it is Smith, who has ten coins in his pocket, who will get the job.

In this case, Smith has a justified true belief that the man who will get the job has ten coins in his pocket. However, most of us are reluctant to attribute knowledge to Smith in this case. It seems that even though he has a justified true belief, Smith just got lucky that his belief is true. If this is right, then Gettier has shown that justification, truth, and belief are insufficient for knowledge, and hence, that the traditional analysis is wrong.

3. A Proposed Solution

The widespread response to the Gettier Problem (as it has come to be known) has been to admit that justification, truth, and belief are individually necessary but jointly insufficient for knowledge and to propose some fourth condition on knowledge. An initially popular proposal was to ban beliefs resulting from false premises from counting as knowledge. Notice that in Gettier’s original case, Smith infers his true belief (that the man who will get the job has ten coins in his pocket) from a false belief (that Jones will get the job and that Jones has ten coins in his pocket).

However, this response was quickly challenged by epistemologists like Roderick Chisholm, Alvin Goldman, and Carl Ginet. Consider this famous counter-example from Goldman to the new proposed analysis:

You are driving through the country. It seems to you as though every so often, you pass a barn. Unbeknownst to you, you are in Fake Barn Country, where nearly all of what seem to be barns are actually just convincing barn façades. At one point, you turn to your travel companion, point to an apparent barn, and say, “There’s a barn.” Luckily, you have managed to point to the one actual barn in Fake Barn Country, so your claim that there’s a barn is true.

Do you know that the thing you point to is a barn? You’ve got a justified true belief that hasn’t been inferred from any false beliefs, but it still doesn’t seem as though you’ve got knowledge. If this is right, then it shows that the no false beliefs fourth condition will not do the trick.

4. Conclusion

Notice that, in discussions of the Gettier Problem, we’ve been mentioning luck a lot. Recognition of this fact has led many contemporary epistemologists to focus their efforts on an analysis of the concept of epistemic luck. If we can determine exactly what this sort of luck is, the thought goes, we can determine (i) what sorts of it are knowledge-destroying5 and (ii) how best to block these sorts of knowledge-destroying luck.6


1 There are at least three (initially apparently distinct) sorts of knowledge: propositional knowledge (knowledge-that), ability knowledge (knowledge-how), and acquaintance knowledge (knowledge-of). For example, you know that you are reading a 1000-word philosophy article, you know how to read, and you know-of your best friend or your partner. This essay (and much of contemporary Anglo-American epistemology) is concerned with propositional knowledge, knowledge-that, only.

2Some technical terminology: The object to be analyzed is called the analysandum (pl. analysanda) and the analysis or analyzing object is called the analysans (pl. analysans).

3 For an introduction to the concept of epistemic justification, see Epistemic Justification: What is Rational Belief? by Todd R. Long. It is worth noting that there is vigorous debate amongst epistemologists regarding whether the terms justification, evidence, and reasons mean the same thing. For the purposes of this essay, we can treat the terms as relevantly synonymous.

4Consider your most pessimistic acquaintance’s frequent apocalyptic predictions. When things do occasionally go wrong and she declares, triumphantly, “I knew it!,” you’re not inclined to claim that she knew anything of the sort—she’s just a petulant naysayer whose naysayings are occasionally true, but nonetheless unjustified, and certainly not knowledge.

5See Engel (1992)

6See Pritchard (2005)


Engel, Mylan, Jr. “Is Epistemic Luck Compatible with Knowledge?” The Southern Journal of Philosophy 30.2 (1992): 59-75.

Gettier, Edmund L. “Is Justified True Belief Knowledge?” Analysis 23.6 (1963): 121. 

Goldman, Alvin I. “Discrimination and Perceptual Knowledge.” The Journal of Philosophy 73.20 (1976): 771-91.

Plato, Theaetetus.

Pritchard, Duncan. Epistemic Luck. New York: Oxford UP, 2005.

Related Essays

Epistemology, or Theory of Knowledge by Thomas Metcalf

Epistemic Justification: What is Rational Belief? by Todd R. Long.

About the Author

Andrew Chapman is a lecturer in philosophy at the University of Colorado, Boulder. He holds a PhD in philosophy from the University of Colorado, Boulder, an MA in philosophy from Northern Illinois University and a BA in philosophy and a BM in bassoon and sound recording technology from Ithaca College. He specializes in epistemology, metaethics, and the history of philosophy (especially Kant and the 20th Century Anglophone and Phenomenological traditions). When not philosophizing, Andrew is skiing, hiking, listening to great music, or playing the bassoon. 

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