- The 'Equivalence of Things' (齐物论) chapter of the Zhuangzi (庄子) (c. 3rd c. B.C.E.)

Once upon a time I, Zhuang Zhou (庄周), dreamt I was a butterfly.
Flapping my wings in true butterfly fashion, I was happy as could be, and I knew nothing of any person named Zhuang Zhou.
But suddenly I awakened, astonished to be Zhuang Zhou.
I still don't know whether as Zhuang Zhou I was dreaming I was a butterfly or whether as a butterfly I was dreaming I was Zhuang Zhou.
There ought to be a difference between Zhuang Zhou and a butterfly, but this is called the transformation of things.
- David K. Jordan translation (adapted)

## Gettier's Challenge

### Skepsis is the Greek word for 'investigation'

There have been several Gettier-style challenges to the JTB or standard analysis of knowledge:
 EXAMPLE 1 (Dharmottara, c. 770 C.E., cited in Nagel, 2014): A fire has been lit to roast meat. The fire has not started sending up smoke The smell of meat has attracted a cloud of insects. From a distance, an observer mistakes the dark swarm of insects above the horizon for smoke ∴ The observer has a justified true belief that there is a fire burning at that spot However, this observer cannot be said to know that there is a fire burning in the distance EXAMPLE 2 (Russell, 1948): Alice looks at the clock on the tower she sees every day to check the time The clock shows 4 o'clock and Alice forms the belief that it is 4 o'clock However, the clock has stopped and it has been showing 4 o'clock for the past 12 hours ∴ Alice has a justified true belief that it is 4 o'clock However, Alice cannot be said to know that it is 4 o'clock

1. In EXAMPLES 1 and 2, we have instances of justified true belief but we do not have instances of knowledge
2. ∴ The JTB analysis of knowledge misfires

Here are Gettier's own examples that challenge the JTB analysis of knowledge:
1. EXAMPLE 3 (Gettier, 1963):
2. Smith and Jones have applied for a job
3. Suppose that Smith has strong evidence for (S1 ∧ S2), where:
1. S1: Jones is the man who will get the job;
2. S2: Jones has 10 coins in his pocket

3. Smith’s evidence for (S1 ∧ S2):
4. EVIDENCE 1: The president of the company has assured Smith that Jones will be selected for the job;
5. EVIDENCE 2: Smith had counted the coins in Jones's pocket a few minutes ago

6. S3: The man who will get the job has 10 coins in his pocket
7. S1 ∧ S2 ⊦ S3
8. Suppose further that, unknown to Smith, it is Smith rather than Jones who will get the job
9. Incidentally, Smith also has 10 coins in his pocket

10. ∴ While S1 and S2 would be false, S3 would be true
11. ∴ Smith would have a justified true belief that S3
12. However, Smith cannot be said to know that S3 is true

1. EXAMPLE 4 (Gettier, 1963):
2. Suppose that Smith has strong evidence for proposition S1:
3. S1: Jones owns a Ford
4. Smith’s evidence for S1:
5. EVIDENCE 1: Jones has at all times in the past within Smith's memory owned a car and always a Ford
6. EVIDENCE 2: Jones has just offered Smith a ride while driving a Ford

7. Suppose that Smith has another friend, Brown, of whose whereabouts he is totally ignorant
8. Smith selects 3 places at random and constructs 3 propositions:
9. S2: Brown is in Boston
10. S3: Brown is in Barcelona
11. S4: Brown is in Brest-Litovsk

12. Here are 3 disjunctive propositions:
13. (S1 ∨ S2), (S1 ∨ S3), and (S1 ∨ S4)
14. S1 ⊦ S1 ∨ S2
15. S1 ⊦ S1 ∨ S3
16. S1 ⊦ S1 ∨ S4

17. Suppose that Jones does not own a Ford but is rather driving a rented car
18. Suppose further that by sheer coincidence and unknown to Smith, Brown is in Barcelona

19. ∴ Smith would have a justified true belief that (S1 ∨ S3) (viz. 'Either Jones owns a Ford or Brown is in Barcelona')
20. However, Smith does not know that (S1 ∨ S3) is true

As EXAMPLES 1-4 show, Gettier-type cases pose a problem (known as the Gettier problem) for the JTB analysis of knowledge