The Gettier Problem

Before Gettier’s paper it was traditionally held in epistemology that someone had knowledge if they believe some proposition P, were justified in believe P, and P was in fact true. If any one of the three criteria were missing when a person had a belief then they did not have knowledge.  To be clear a person believes a proposition if they think a proposition is true. A person is justified in believing a proposition if they have evidence the proposition is true. Lastly, the proposition someone is justified in believing must also be true.  In other words justified true beliefs were considered necessary and sufficient conditions for knowledge.

Gettier is working with two assumptions that are not widely disputed in epistemology. First is that justification is weak, which means that a person can be justified in a belief but still be wrong. Secondly, he is working with the assumption that if a person is justified in believing X and correctly infers Z from X then a person a person is justified in believing Z.  Here is an example of this inference:  a person who is justified in believing Obama is president then that person is justified in believing the president’s last name starts with O. They inferred correctly from Obama being the president to the president’s last name beginning with O.

 Now that the background information is out of the way, Gettier’s argument attempts to show that justified true belief is not sufficient for knowledge. However, Gettier does not make an argument against justified true belief being necessary for knowledge.  By sufficient it is meant that justified true belief does not guarantee knowledge. To illustrate this Gettier gives this type of example: Smith and Jones both apply for a promotion. Their boss informs Smith that Jones will get the promotion and Jones has no reason to doubt his boss since his boss is an honest man. Smith then believes Jones will get the promotion (1). Smith also knows that Jones has ten coins in his pocket (2). Because of (1) and (2) Smith infers (3) that the person who gets the promotion has ten coins in their pocket. However, when it becomes time to formally announce who gets the promotion, Smith was promoted. Coincidentally, Smith has ten coins in his pocket.  It seems intuitive that Smith does not have knowledge of the proposition: The person who gets the promotion has ten coins in their pocket. This is problematic because Smith fulfilled the traditional criteria of knowledge by believing the true proposition; the person who gets the promotion has ten coins in their pocket, being justified in believing it. Since, this is a clear case of a person having justified true belief and not having knowledge then justified true belief is not sufficient for knowledge.   Justified true belief is still necessary for knowledge meaning that if any of these three are missing then a person does not have knowledge. Given Gettier’s argument justified true belief needs another criterion if it is going to be sufficient for knowledge.