Amazingly, Plato’s view that knowledge is justified true belief was generally accepted until the 20th century (over 2,000 years!). But once this analysis was questioned, a flurry of developments occurred within epistemology in the latter half of the 20th century. This section discusses the counterexample method at play in the dialectic concerning what knowledge is. Plato’s JTB analysis was the first to come under scrutiny.
In 1963, American philosopher Edmund Gettier (1927–2021) published a short paper titled “Is Justified True Belief Knowledge?,” which upended the JTB canon in Western philosophy. Gettier presents two counterexamples to Plato’s analysis of knowledge. In these counterexamples, a person seems to have a justified true belief, yet they do not seem to have knowledge. While Gettier is credited with the first popular counterexample to the JTB account, he was not the first philosopher to articulate a counterexample that calls into question Plato’s analysis. But because Gettier published the first influential account, any example that seems to undermine Plato’s JTB account of knowledge is called a Gettier case. Gettier cases illustrate the inadequacy of the JTB account—a problem referred to as the Gettier problem.
Dharmakīrti’s Mirage
The earliest known Gettier case, long predating the term, was conceived by the eighth century Indian Buddhist philosopher Dharmakīrti. Dharmakīrti’s case asks one to imagine a weary nomad traveling across the desert in search of water (Dreyfus 1997). The traveler crests a mountain and sees what appears to be an oasis in the valley below, and so comes to believe that there is water in the valley. However, the oasis is just a mirage. Yet there is water in the valley, but it is just beneath the surface of the land where the mirage is. The traveler is justified in believing there is water in the valley due to sensory experience. Furthermore, it is true that there is water in the valley. However, the traveler’s belief does not seem to count as knowledge. Dharmakīrti’s conclusion is that the traveler cannot be said to know there is water in the valley because the traveler’s reason for believing that there is water in the valley is an illusory mirage.
Russell’s Case
Perhaps you’ve heard the phrase “Even a broken clock is right twice a day.” The next case relies on this fact about broken clocks. In 1948, Bertrand Russell offered a case in which a man looks up at a stopped clock at exactly the correct time:
There is the man who looks at a clock which is not going, though he thinks it is, and who happens to look at it at the moment when it is right; this man acquires a true belief as to the time of day, but cannot be said to have knowledge. (Russell 1948, 154)
Imagine that the clock the man looks at is known for its reliability. Hence, the man is justified in believing that the time is, for example, 4:30. And, as the cases supposes, it is true that it is 4:30. However, given that the clock is not working and that the man happens to look up at one of the two times a day that the clock is correct, it is only a matter of luck that his belief happens to be true. Hence, Russell concludes that the man cannot be said to know the correct time.
Fake Barn Country
The last Gettier case we will look at is from American philosopher Carl Ginet (b. 1932) (Goldman 1976). Henry is driving through a bucolic area of farmland and barns. What he doesn’t realize, however, is that the area is currently being used as a movie set, and all the barns save one are actually barn facades. While looking at one of the barns, Henry says to himself, “That is a barn.” Luckily for Henry, the one he points to is the one true barn in the area. Again, all the conditions in Plato’s analysis of knowledge are met. It is true that Henry is looking at a real barn, and he believes it is a barn. Furthermore, he has come to this belief utilizing justifiable means—he is using his vision, in normal lighting, to identify a common object (a barn). Yet one cannot reasonably say that Henry knows the barn is a barn because he could have, by chance, accidentally identified one of the fake barns as a true barn. He fortunately happens to pick the one true barn.
Table 7.2 summarizes the Gettier cases discussed in this chapter.
| Case | Proposed by | Description | How does this challenge Plato’s characterization of knowledge as justified, true belief? |
|---|---|---|---|
| Dharmakīrti’s Mirage | Eighth century Indian Buddhist philosopher Dharmakīrti | A person travelling in the dessert sees a mirage of a watery oasis in a valley and concludes that there is water in the valley. In fact, there is water in the valley, but it is beneath the surface and not visible. | The traveler cannot be said to know there is water in the valley because the traveler’s reason for believing that there is water in the valley is an illusory mirage. |
| Russell’s Case | British philosopher Bertrand Russell (1872 – 1970) | A man looks at a stopped clock at exactly the right time and correctly concludes the actual time. | It is only a matter of luck that the man’s belief about what time it is happens to be true. Hence, the man cannot be said to know the correct time. |
| Fake Barn Country | American philosopher Carl Ginet (b. 1932) | A person driving through a landscape that is being used as a movie and is full of fake barns happens to look at the one barn that is real and conclude, “this is barn.” | The person cannot reasonably be said to know the barn is a real barn because they could easily have identified one of the fake barns as a real barn and been wrong. |
The content of this course has been taken from the free Philosophy textbook by Openstax