Plato — Theaetetus & Getter — Is Justified True Belief Knowledge?
In these readings, we continue our (entirely appropriate) obsessive quest to define knowledge, via a Socratic dialogue from Plato and a short essay from Gettier in which he attempts to disprove the formulation we’ve seen in several places throughout the course. We face the fundamental problem of human knowledge in Plato, and in following Gettier we demolish the best definition of human knowledge we’ve seen.
Let us start with Gettier, for though he refers to the Plato piece, to my mind Plato’s argument encompasses (or at least eclipses) his. He briefly outlines the three requirements for knowledge that we have seen in a number of places: 1) P is true, 2) S believes P, and 3) S is justified in believing P. We’ve previously seen similar definitions in, eg, Nozick’s Philosophical Explanations.
Having set up these friendly and familiar conditions for knowledge, Gettier presents us with two simple scenarios in which an actor believes P, is justified in believing P, and P is true — yet the actor clearly does not know P because he believes P for the wrong (justified!) reasons! And so our favorite formulation of knowledge is either deficient or just plain wrong.
Plato’s writing on knowledge is even more damning than Gettier’s. In the space of five pages, Socrates and Theaetetus attempt to define knowledge and then, having run through a number of possible predicates (including many variations on the three parts presented above) throw their hands into the air and declare their inability to complete the task. Their final formulation, which stood in all situations they could think of, fell for the simplest of reasons: it included knowledge in the definition.
So the quest to define knowledge usefully goes on, but I confess I don’t understand why anybody has kept searching. To my mind, we have in fact defined knowledge as justified true belief, and the thing we keep bumping up against is not a flaw in our definition of knowledge. It is in our status as humans, with limited sensory capability and memory. Knowledge is like Plato’s forms, which exist perfectly and are only roughly imitated in the real world. An omnipotent being operating under knowledge as justified true belief could not break the definition because upon any question he would simply justify the belief by checking the status of every thing related to the piece of knowledge in question. As human beings, we do not have such a luxury and so we cannot know, we can only believe; when we speak of knowledge we are speaking of an approximation by strong belief. This answer satisfies me and I do not understand why so many people attempt to define perfect knowledge in a way that allows humans to possess it.