The Gettier Problem
Consider this: what is knowledge? That’s one of the most fundamental questions in philosophy. Philosophers can and have argued about it for millennia. There are a few things that are generally agreed upon, though: first, knowledge must be true. You can’t know something false. You can’t know the moon is made of cheese; you can believe it, but it’s not knowledge. So knowledge is (at least) true. You can’t know something you don’t believe. So knowledge is (at least) belief. And you can’t know something by accident: if someone asks you to guess a random number between one and one million, and that number happens to be the one you thought of, you didn’t know, even if it was a belief and it was true. So knowledge is (at least) justified. These three characteristics are widely agreed upon: knowledge is (at least) Justified True Belief, or JTB for short. Indeed, to many, it seems obvious that this isn’t just required but sufficient for knowledge — that knowledge is just JTB, nothing more and nothing less.
But! There’s a twist:
The tripartite analysis of knowledge as JTB has been shown to be incomplete. There are cases of JTB that do not qualify as cases of knowledge. JTB, therefore, is not sufficient for knowledge. Cases like that — known as Gettier-cases — arise because neither the possession of evidence nor origination in reliable faculties is sufficient for ensuring that a belief is not true merely because of luck. Consider the well-known case of barn-facades: Henry drives through a rural area in which what appear to be barns are, with the exception of just one, mere barn facades. From the road Henry is driving on, these facades look exactly like real barns. Henry happens to be looking at the one and only real barn in the area and believes that there’s a barn over there. Henry’s belief is justified, according to TK [the traditional approach], because Henry’s visual experience justifies his belief. According to NTK [the non-traditional approach], his belief is justified because Henry’s belief originates in a reliable cognitive process: vision. Yet Henry’s belief is plausibly viewed as being true merely because of luck. Had Henry noticed one of the barn-facades instead, he would also have believed that there’s a barn over there. There is, therefore, broad agreement among epistemologists that Henry’s belief does not qualify as knowledge.
To state conditions that are jointly sufficient for knowledge, what further element must be added to JTB? This is known as the Gettier problem.
In case you couldn’t tell from my frequent linking, I love the Stanford Encyclopedia of Philosophy. SEP rocks, and almost always has the best article on whatever philosophical problem or approach you’re looking for, at least within analytic philosophy.
