section_path: Definition
section_name: Definition
paragraph_text: Definition
  
  Epistemology is the philosophical study of knowledge. Also called theory of knowledge, it examines what knowledge is and what types of knowledge there are. It further investigates the sources of knowledge, like perception, inference, and testimony, to determine how knowledge is created. Another topic is the extent and limits of knowledge, confronting questions about what people can and cannot know. Other central concepts include belief, truth, justification, evidence, and reason. Epistemology is one of the main branches of philosophy besides fields like ethics, logic, and metaphysics. The term is also used in a slightly different sense to refer not to the branch of philosophy but to a particular position within that branch, as in Plato 's epistemology and Immanuel Kant 's epistemology.
  
  As a normative field of inquiry, epistemology explores how people should acquire beliefs. This way, it determines which beliefs fulfill the standards or epistemic goals of knowledge and which ones fail, thereby providing an evaluation of beliefs. Descriptive fields of inquiry, like psychology and cognitive sociology, are also interested in beliefs and related cognitive processes. Unlike epistemology, they study the beliefs people have and how people acquire them instead of examining the evaluative norms of these processes. Epistemology is relevant to many descriptive and normative disciplines, such as the other branches of philosophy and the sciences, by exploring the principles of how they may arrive at knowledge.
  
  The word epistemology comes from the ancient Greek terms ἐπιστήμη (episteme, meaning knowledge or understanding) and λόγος (logos, meaning study of or reason), literally, the study of knowledge. Yet, even though ancient Greek philosophers practiced what is today considered epistemology, they did not understand their investigations in these terms. The word was only coined in the 19th century to label this field and conceive it as a distinct branch of philosophy.