The Gettier problem is a philosophical dilemma, questioning whether any piece of information, which happens to be true, but is believed for invalid reasons, such as a faulty premise, is indeed knowledge. The problem is named after American philosopher Edmund Gettier, who wrote about the problem in 1963.
Gettier Problem and Knowledge
The question of what constitutes knowledge is as old as philosophy itself. A justified true belief (JTB) claims that meaning must meet certain criteria. Under this, a subject (S) knows that a proposition (P) is true if and only if, P is true, and S believed that P is true, and S is justified in believing that P is true. Gettier argued that there are cases when belief are both true and justified, but not genuine knowledge, holding that the JTB account is false.
One scenario often used to explain the Gettier problem is the sheep in the field. If we picture a person standing outside a field, looking at something that looks like a sheep, but is in fact a dog disguised as a sheep. The person believes there are sheep in the field, and in this case they are right because there are other sheep just behind a hill. Thus, the person has a justified belief. The question remains as to whether that belief is knowledge. In this case, the Gettier problem says that justified true belief has come about (there are sheep in the field) despite a faulty premise (what the viewer thought was a sheep was actually a dog).