section_path: Definitions/Analysis of knowledge
section_name: Analysis of knowledge
paragraph_text: Analysis of knowledge
  
  An often-discussed definition characterizes knowledge as justified true belief. This definition identifies three essential features: it is (1) a belief that is (2) true and (3) justified. Truth is a widely accepted feature of knowledge. It implies that, while it may be possible to believe something false, one cannot know something false. That knowledge is a form of belief implies that one cannot know something if one does not believe it. Some everyday expressions seem to violate this principle, like the claim that "I do not believe it, I know it!" But the point of such expressions is usually to emphasize one's confidence rather than denying that a belief is involved.
  
  The main controversy surrounding this definition concerns its third feature: justification. This component is often included because of the impression that some true beliefs are not forms of knowledge, such as beliefs based on superstition, lucky guesses, or erroneous reasoning. For example, a person who guesses that a coin flip will land heads usually does not know that even if their belief turns out to be true. This indicates that there is more to knowledge than just being right about something. These cases are excluded by requiring that beliefs have justification for them to count as knowledge. Some philosophers hold that a belief is justified if it is based on evidence, which can take the form of mental states like experience, memory, and other beliefs. Others state that beliefs are justified if they are produced by reliable processes, like sensory perception or logical reasoning.
  
  The definition of knowledge as justified true belief came under severe criticism in the 20th century, when epistemologist Edmund Gettier formulated a series of counterexamples. They purport to present concrete cases of justified true beliefs that fail to constitute knowledge. The reason for their failure is usually a form of epistemic luck: the beliefs are justified but their justification is not relevant to the truth. In a well-known example, someone drives along a country road with many barn facades and only one real barn. The person is not aware of this, stops in front of the real barn by a lucky coincidence, and forms the justified true belief that they are in front of a barn. This example aims to establish that the person does not know that they are in front of a real barn, since they would not have been able to tell the difference. This means that it is a lucky coincidence that this justified belief is also true.
  
  According to some philosophers, these counterexamples show that justification is not required for knowledge and that knowledge should instead be characterized in terms of reliability or the manifestation of cognitive virtues. Another approach defines knowledge in regard to the function it plays in cognitive processes as that which provides reasons for thinking or doing something. A different response accepts justification as an aspect of knowledge and include additional criteria. Many candidates have been suggested, like the requirements that the justified true belief does not depend on any false beliefs, that no defeaters are present, or that the person would not have the belief if it was false. Another view states that beliefs have to be infallible to amount to knowledge. A further approach, associated with pragmatism, focuses on the aspect of inquiry and characterizes knowledge in terms of what works as a practice that aims to produce habits of action. There is still very little consensus in the academic discourse as to which of the proposed modifications or reconceptualizations is correct, and there are various alternative definitions of knowledge.