What are the main points of Gettier's famous paper on justified belief and knowledge?
Edmund Gettier's 1963 paper Is Justified True Belief Knowledge begins by showing that there has historically been general agreement over what it means to know that P. The classical definition, beginning with Plato, holds that an agent X knows that P if and only if:
- X believes that P
- P is true
- X is justified in believing that P
Gettier's concern in his paper is to demonstrate that this definition of knowledge is inadequate, and in particular that there are cases of justified true belief which are not cases of knowledge. He provides two counterexamples to the standard account. In the first of these, two men - Smith and Jones - are both applying for a job. Smith believes that he has messed up his interview and that Jones will get the job; furthermore, he happens to know that Jones has ten coins in his pocket. From these he draws the conclusion that the man who will get the job has ten coins in his pocket.
Smith has in fact done far better than he thought, and gets the job. As it so happens, he also has ten coins in his pocket. This means that:
- Smith believed that the man who would get the job had ten coins in his pocket
- It was true that the man who got the job had ten coins in his pocket
- Smith was justified in believing that the man who would get the job had ten coins in his pocket
All of the conditions of the classical definition of knowledge are met- yet intuitively this does not seem like a case of knowledge. This shows that justified true belief is not adequate to define our intuitive sense of what knowledge is.
There has been a great deal of work attempting to tighten up the definition of knowledge - requiring that one's belief be "not easily wrong" or "truth-tracking" or some similar. Personally I think we should just accept that "knowledge" is not a well-defined term, and while it serves purposes in everyday conversation these are less like "I have a JTB that P" but rather closer to "I strongly believe that P" or "I am indeed aware that P". The search for a definition of truth is part and parcel of the mistaken project of trying to obtain genuine certainty. This is an unrealistic and indeed impossible standard.