What is knowledge?
Acquaintance knowledge
I know my mother.
Procedural knowledge
I know how to ride a bike.
Propositional knowledge
I know that God exists.
When ‘that’ follows ‘know’ it usually indicates a proposition.
A proposition will be either true or false.
Propositional knowledge is the sort of interest to epistemologists.
The justified true belief theory of knowledge
Knowledge is comonly understood to be a kind of belief.
For any proposition, P, a person, S, knows that P is true if and only if
2. S is justified in believing P.
3. P is true.
1, 2, and 3 are considered to be individually necessary and collectively sufficient conditions for knowledge.
What does this mean?
Why 1? 1 in individually necessaey but not in itself sfficient.
Why 2? 2 is individually necessary but not in itself sufficient.
Why 3? 3 is individually necessary but not in itself sufficient.
1, 2, and 3 are collectively sufficient.
It will be worth noticing that...
1 and 2 are facts about S.
3 is a fact about P.
Gettier problems
Gettier brings out an important fact.
1 and 2 do not imply 3.
It might happen that 1 and 2 are true while 3 is false.
His argument against the justified true belief theory relies on a premise.
If S believes P, and S is justified in believing P, and P entails Q, and S knows that P entails Q, and S derives Q on the basis of his justification for believing P, then S is justified in believing Q.
Got that?
Gettier’s illustration
The promotion case
Smith believes P, Jones will get the job and Jones has ten coins in his pocket.
S is justified in believing P. (The trustworthy boss has assured Smith that Jones will get the job and Smith has counted the coins in Jones's pocket.)
S knows that P entails Q, the man who will get the job has ten coins in his pocket.
Smith infers and, so, believes Q on the grounds that he has for believing P.
Smith is thus justified in believing Q.
It turns out that Smith gets the job and that, by chance, Smith also has ten coins in his pocket. (The boss wanted to surprise Smith.)
Q was true. Q was a justified true belief.
But Smith did not knows Q.
P, the proposition from which S inferred Q was inferred, was false.
Additional illustrations
The cow in the field case
A farmer tells a milkman that he has lost his cow. The milkman, having earlier seen the farmer's cow in the field, assures the farmer that his cow is indeed there. The farmer looks out and sees a black and white object in the distance that resembles his cow. The farmer believes on the basis of the milkman's testimony together with his observation, that his cow is in the field. He is justified in believing this. However, it was not his cow that he saw but some black and white debris that had blown into his field. Nevertheless, the farmer's cow was in the field but hidden behind a bush. The farmer's belief was justified and it was true, but he did not know that his cow was in the field.
The steam clock case
Each morning at 9am, Smith sets his watch by a steam clock, knowing that the clock is highly reliable. One day the steam clock breaks down. Exactly 12 hours later, Smith sets his watch by the clock. He believes it to be 9am, he is justified in believing this, and it is 9am. But he doesn’t know this.
The payoff of the Gettier cases is that the theory permits too much.
It permits us to say that some things are known that are not.
For each of the above...
Was the proposition believed?
Was the proposition true?Was the belief justified?
Solutions to the Gettier problems
The reason for believing must be conclusive. One would not have that reason if the belief were false.
In each case, the grounds for believing did not guarantee the truth of the proposition.
Why not strengthen 2 so that 1 and 2 imply 3?
Then the definition would permit too little.
Perhaps knowledge is one of those ideas that do not cleanly map on to the world.
The justification cannot be based on a false belief
In each of the cases described, the persons justification was based on a false belief.
That Jones would get the job
That the thing he saw was his cow
That the clock was functioning properly
The person must come to believe the proposition by a causal connection to its truth condition.
In each case, the belief was not produced by the right fact.
That Smith had ten coins in his pocket
That it was his cow that he saw
That the time was that of a properly functioning clock
Th person comes to believe the proposition in the right way?
1. S believes P.
2. S is justified in believing P.
3. P is true.
4. S comes to believe P rightly.
What is the right way?
Does S know that S comes to believe P in the right way?
If so, then the question about knowledge is begged. (How does he know this?)
If not, then a new problem arises.
S knows P only if S knows that S knows P. (KK principle)
If S does not know that he came to believe P in the right way, S does not know that he knows P.
