Summary

Epistemology is the study of knowledge and its associated concepts, such as truth and justification. The discipline of epistemology uses many tools, including conceptual analysis, argumentation, and research. Traditional epistemology focuses on propositional knowledge, which is knowledge of facts or statements. There are other types of knowledge, including procedural knowledge and knowledge by acquaintance. Because knowledge and justification are treated as valuable and epistemology studies these concepts, epistemology is both descriptive and a normative discipline.

The traditional understanding of knowledge, which comes from Plato, is that it consists of justified true belief. Plato’s account was generally accepted until the 1960s, when philosopher Edmund Gettier offered counterexamples, known as Gettier cases. Gettier cases reveal that justified true belief is not sufficient for knowledge, a problemed called the Gettier problem. Many theorists attempt to solve the Gettier problem by strengthening Plato’s account. Fixes include adding another condition to the definition and clarifying what justification is.

Justification for a belief makes the belief more likely to be true. How justification works and the nature of justification are important to the study of epistemology. Internalism is the view that justification is entirely dependent on factors internal to the mind of the knower. Externalism is the view that at least some elements that determine justification are external to the mind of the knower. Attempts to solve the Gettier problem have come in both internal and external forms. Theorists also study justification as it exists in the structure of entire belief systems. Foundationalists believe that all beliefs rest on a foundation of basic beliefs, while coherentists hold that beliefs exist in a web of mutually supporting and consistent beliefs. Justification has many sources, but all of them are fallible, which means that even justified beliefs can be false.

Skepticism is the view that all or some of our knowledge is impossible. A global skeptic rejects the possibility of all knowledge and often focuses on the possibility of justification for beliefs of the external world. Global skeptics usually put forth a skeptical hypothesis—a way that the world could be that would entail that all our beliefs are false—and show that we cannot rule out the hypothesis. Skeptical hypotheses include the possibility that we are dreaming, that a powerful demon is tricking us, and that we are brains in vats or trapped in virtual reality. All skeptical arguments take advantage of the fact that we cannot rule out skeptical hypotheses on the evidence we have. Those who argue against skepticism claim we do not need the level of justification that skeptics claim we do.

Applied epistemology uses the concepts, methods, and theories particular to epistemology and applies them to current social issues and practices. An important area of applied epistemology is social epistemology, which focuses on the social facets of knowledge and justification and how groups form beliefs. Testimony refers to how we gain knowledge from and share knowledge with others. Social epistemology studies how to evaluate our beliefs when they conflict with the testimony of others. Social epistemology also illuminates how injustice can arise in epistemological endeavors in a social world. Testimonial injustice occurs when the opinions of individuals are systematically discounted or ignored unfairly. Hermeneutical injustice occurs when a society’s language and concepts cannot adequately capture the experience of all its members.