Traditional Definition of Knowledge: a belief that is true and justified. Sam knows P if (1) P is true, (2) Sam believes P and (3) Sam’s belief is justified.
Gettier. Gettier is famous for providing counterexamples to the traditional definition of knowledge. He provided examples where someone has a justified and true belief but where it is obvious that the belief is not knowledge. There are two ways that justified true beliefs can fail to be knowledge. First of all, the truth of the statement can be based on luck. Second, under slightly different circumstances, the belief would either be (a) false or (b) not believed.
Another Gettier Case of the First Kind (Conjunctive). Poppy starts with a belief that is a conjunctive proposition, e.g. “I believe that Obama is wearing a blue suit and that Obama is a Muslim.” Poppy is justified believing this because Poppy sees Obama in front of her and she sees that Obama is wearing a blue suit. Also, Poppy reads and watches news from outlets that tell her that Obama is a Muslim. From this conjunctive proposition, she infers a simpler version of the conjunctive belief: “I believe that a man wearing a blue suit is Muslim.”
Obama is not a Muslim. He is a Christian. However, say there is a man behind Obama that Poppy does not see, Mo. Mo is Muslim and Mo is wearing a blue suit. It just so happens that Poppy's belief “I believe that a man wearing a blue suit is Muslim.” is true, but only because she is lucky. Her basis for the belief, which is the belief that Obama is wearing a blue suit and Obama is a Muslim, is false. Gettier would think that this is a case where Poppy had a justified true belief that is not knowledge.
No-False Premise Solution to the Gettier Problem. In the case above as well as in the case where Smith believes that the man who gets the job has ten coins in his pocket, the justified true belief that is not knowledge is based on a false premise. In the case where one believes that the man wearing a blue suit is a Muslim, this belief is based on the false belief that Obama is a Muslim. In the case with Smith and Jones, Smith’s true belief that the man who gets the job has ten coins in his pocket is based on the false belief, “Jones will get the job and Jones has ten coins.” Some philosophers say that the real problem in the Gettier cases is the beliefs are being based on false premises. They say that we can only get knowledge when we reason through true premises.
Feldman, who thinks that the no-false premise solution does not solve the Gettier problem, proposes a case where a subject does not reason through a false premise but where still have a case of justified true belief that is not knowledge.
First Reason to Reject the No-False Premise Solution: The No-False Premise Solution Does Not Exclude All Gettier Cases. People can still reason through all true premises and have justified true beliefs that are not knowledge. This means that even if we avoid using false premises, we can still come up with Gettier-type cases. e.g. Smith believes the following:
1. The boss said, “Jones get the job and Jones has ten coins.”
2. The boss is usually reliable.
3. The person who gets the job has ten coins.
The premises (#1 & #2) are true and justified. The conclusion (#3) is also true and justified but it is still not knowledge. In this case, Smith as reasoned through all true premises (in accordance with the No-False Premise Solution) but we still have a Gettier case. Because we can still think of Gettier cases where the no-false premise requirement is met, the no-false premise solution is not restrictive enough.
Second Reason to Reject the No-False Premise Solution: A Case of Actual Knowledge that Withstands the No-False Premise Requirement. This is meant to be a case where we have legitimate knowledge that is formed based on a false premise, in which case it would be too restrictive to say that we must always reason through all true premises. Sam knows a ton of stuff about marriage ceremonies. After attending a wedding ceremony of two friends, he has justified belief that the two have been married before his eyes. On the basis of this belief, he believes that the two people are currently married. It turns out, Sam’s friends actually got married the day earlier in a private civil ceremony. His original belief, that the two were married before his eyes, is false. Still, this is a case where someone has reasoned through a false belief. Sven presents this as an example where one can use a false premise to get a justified true belief that IS knowledge. Because the no-false premise solution ends up excluding legitimate examples of knowledge, it is too restrictive.
Final Say on No-False Premise Solution. Dr. Bernecker has given two reasons why we should reject the no-false premise requirement. First, the requirement does not seem restrictive enough. We can still come up with Gettier cases even if someone only reasons with true premises. Second, the requirement also seems too restrictive. He thinks that there will be times when someone reasons with a false premise and actually does end up with knowledge. Whether we agree with these reasons for rejecting the no-false premise solution is a separate issue.