Much of the debate in this field has focused on analyzing the nature of knowledge and how it relates to similar notions such as truth, belief, and justification. It also deals with the means of production of knowledge, as well as skepticism about different knowledge claims. In other words, epistemology primarily addresses the following questions: "What is knowledge?", "How is knowledge acquired?", and "What do people know?".
The Gettier problem is considered a fundamental problem in modern epistemology or first-order logic, issuing from counter-examples to the definition of knowledge as justified true belief, and dealing extensively with the concept of justified true belief (JTB), and the scope of the concept of JTB, as well as those attacks upon JTB which Gettier exemplars introduce. The problem owes its name to a three-page paper published in 1963, by Edmund Gettier, called "Is Justified True Belief Knowledge?", in which Gettier argues that this is not necessarily the case. Many or most analytic philosophers would wish to be able to hold to what is known as the JTB account of knowledge: the claim that knowledge can be conceptually analyzed as justified true belief — which is to say that the meaning of sentences such as "Smith knows that it rained today" can be given with the following set of necessary and jointly sufficient conditions:
Goldman's early book, A Theory of Human Action (a revised version of his Ph.D. thesis), presents a systematic way of classifying and relating the many actions we perform at any time. Its influence was broad and can be found in, among other writings, John Rawls' book A Theory of Justice. Goldman's early work in action theory soon gave way to work in other branches of philosophy, most influentially epistemology.