Knowledge
Knowledge is an awareness of facts, a familiarity with individuals and situations, or a practical skill. Knowledge of facts, also called propositional knowledge, is often characterized as true belief that is distinct from opinion or guesswork by virtue of justification. While there is wide agreement among philosophers that propositional knowledge is a form of true belief, many controversies focus on justification. This includes questions like how to understand justification, whether it is needed at all, and whether something else besides it is needed. These controversies intensified in the latter half of the 20th century due to a series of thought experiments called Gettier cases that provoked alternative definitions.
Knowledge can be produced in many ways. The main source of empirical knowledge is perception, which involves the usage of the senses to learn about the external world. Introspection allows people to learn about their internal mental states and processes. Other sources of knowledge include memory, rational intuition, inference, and testimony. According to foundationalism, some of these sources are basic in that they can justify beliefs, without depending on other mental states. Coherentists reject this claim and contend that a sufficient degree of coherence among all the mental states of the believer is necessary for knowledge. According to infinitism, an infinite chain of beliefs is needed.
The main discipline investigating knowledge is epistemology, which studies what people know, how they come to know it, and what it means to know something. It discusses the value of knowledge and the thesis of philosophical skepticism, which questions the possibility of knowledge. Knowledge is relevant to many fields like the sciences, which aim to acquire knowledge using the scientific method based on repeatable experimentation, observation, and measurement. Various religions hold that humans should seek knowledge and that God or the divine is the source of knowledge. The anthropology of knowledge studies how knowledge is acquired, stored, retrieved, and communicated in different cultures. The sociology of knowledge examines under what sociohistorical circumstances knowledge arises, and what sociological consequences it has. The history of knowledge investigates how knowledge in different fields has developed, and evolved, in the course of history.
Definitions
Knowledge is a form of familiarity, awareness, understanding, or acquaintance. It often involves the possession of information learned through experience and can be understood as a cognitive success or an epistemic contact with reality, like making a discovery. Many academic definitions focus on propositional knowledge in the form of believing certain facts, as in "I know that Dave is at home". Other types of knowledge include knowledge-how in the form of practical competence, as in "she knows how to swim", and knowledge by acquaintance as a familiarity with the known object based on previous direct experience, like knowing someone personally.Knowledge is often understood as a state of an individual person, but it can also refer to a characteristic of a group of people as group knowledge, social knowledge, or collective knowledge. Some social sciences understand knowledge as a broad social phenomenon that is similar to culture. The term may further denote knowledge stored in documents like the "knowledge housed in the library" or the knowledge base of an expert system. Knowledge is closely related to intelligence, but intelligence is more about the ability to acquire, process, and apply information, while knowledge concerns information and skills that a person already possesses.
The word knowledge has its roots in the 12th-century Old English word cnawan, which comes from the Old High German word gecnawan. The English word includes various meanings that some other languages distinguish using several words. In ancient Greek, for example, four important terms for knowledge were used: epistēmē, technē, mētis, and gnōsis. The main discipline studying knowledge is called epistemology or the theory of knowledge. It examines the nature of knowledge and justification, how knowledge arises, and what value it has. Further topics include the different types of knowledge and the limits of what can be known.
Despite agreements about the general characteristics of knowledge, its exact definition is disputed. Some definitions only focus on the most salient features of knowledge to give a practically useful characterization. Another approach, termed analysis of knowledge, tries to provide a theoretically precise definition by listing the conditions that are individually necessary and jointly sufficient, similar to how chemists analyze a sample by seeking a list of all the chemical elements composing it. According to a different view, knowledge is a unique state that cannot be analyzed in terms of other phenomena. Some scholars base their definition on abstract intuitions while others focus on concrete cases or rely on how the term is used in ordinary language. There is also disagreement about whether knowledge is a rare phenomenon that requires high standards or a common phenomenon found in many everyday situations.
Analysis of knowledge
An often-discussed definition characterizes knowledge as justified true belief. This definition identifies three essential features: it is a belief that is true and 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.
Types
A common distinction among types of knowledge is between propositional knowledge, or knowledge-that, and non-propositional knowledge in the form of practical skills or acquaintance. Other distinctions focus on how the knowledge is acquired and on the content of the known information.Propositional
Propositional knowledge, also referred to as declarative and descriptive knowledge, is a form of theoretical knowledge about facts, like knowing that "2 + 2 = 4". It is the paradigmatic type of knowledge in analytic philosophy. Propositional knowledge is propositional in the sense that it involves a relation to a proposition. Since propositions are often expressed through that-clauses, it is also referred to as knowledge-that, as in "Akari knows that kangaroos hop". In this case, Akari stands in the relation of knowing to the proposition "kangaroos hop". Closely related types of knowledge are know-wh, for example, knowing who is coming to dinner and knowing why they are coming. These expressions are normally understood as types of propositional knowledge since they can be paraphrased using a that-clause.Propositional knowledge takes the form of mental representations involving concepts, ideas, theories, and general rules. These representations connect the knower to certain parts of reality by showing what they are like. They are often context-independent, meaning that they are not restricted to a specific use or purpose. Propositional knowledge encompasses both knowledge of specific facts, like that the atomic mass of gold is 196.97 u, and generalities, like that the color of leaves of some trees changes in autumn. Because of the dependence on mental representations, it is often held that the capacity for propositional knowledge is exclusive to relatively sophisticated creatures, such as humans. This is based on the claim that advanced intellectual capacities are needed to believe a proposition that expresses what the world is like.