For 10 points, name this concept which is studied in epistemology.
According to Timothy Williamson, this concept is unanalyzable. Plato's dialogue Theaetetus deals with the definition of this concept. Its propositional variety is distinguished from the procedural variety, and it can be classified as a priori or a posteriori. Gettier problems are used to argue against the traditional definition of this concept as (*) justified true belief. For 10 points, name this concept which is studied in epistemology.
According to Timothy Williamson, this concept is unanalyzable.
knowledge