Knowledge

Knowledge is often defined as justified true belief.

Many philosophers define knowledge as justified true belief (JTB). This definition characterizes knowledge through three essential features: as (1) a belief that is (2) true and (3) justified.[4][8] In the dialogue Theaetetus by the ancient Greek philosopher Plato, Socrates pondered the distinction between knowledge and true belief but rejected the JTB definition of knowledge.[27][28] The most widely accepted feature is truth: one can believe something false but one cannot know something false.[5][6] A few ordinary language philosophers have raised doubts that knowledge is a form of belief based on everyday expressions like "I do not believe that; I know it".[4][5][8] Most theorists reject this distinction and explain such expressions through ambiguities of natural language.[4][5]

The main controversy surrounding the JTB definition concerns its third feature: justification.[1][4][8] This component is often included because of the impression that some true beliefs are not forms of knowledge. Specifically, this covers cases of superstition, lucky guesses, or erroneous reasoning. The corresponding beliefs may even be true but it seems there is more to knowledge than just being right about something.[4][5][11] The JTB definition solves this problem by identifying proper justification as the additional component needed, which is absent in the above-mentioned cases. Many philosophers have understood justification internalistically (internalism): a belief is justified if it is supported by another mental state of the person, such as a perceptual experience, a memory, or a second belief. This mental state has to constitute a sufficiently strong evidence or reason for the believed proposition. Some modern versions modify the JTB definition by using an externalist conception of justification instead. This means that justification depends not just on factors internal to the subject but also on external factors. They can include, for example, that the belief was produced by a reliable process or that the believed fact caused the belief.[1][4][5]

The Gettier problem is motivated by the idea that some justified true beliefs do not amount to knowledge.

The JTB definition came under severe criticism in the 20th century, when Edmund Gettier gave a series of counterexamples.[29] 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 justification is not relevant to the truth.[4][5][8] In a well-known example, there is a country road with many barn facades and only one real barn. The person driving is not aware of this, stops by a lucky coincidence in front of the real barn, and forms the belief that he is in front of a barn. It has been argued that this justified true belief does not constitute knowledge since the person wouldn't have been able to tell the difference without the fortuitous accident.[30][31][32] So even though the belief is justified, it is a lucky coincidence that it is also true. The responses to these counterexamples have been diverse. According to some, they show that the JTB definition of knowledge is deeply flawed and that a radical reconceptualization of knowledge is necessary, often by denying justification a role.[1] This can happen, for example, by replacing justification with reliability or by understanding knowledge as the manifestation of cognitive virtues. Other approaches include defining it in regard to the cognitive role it plays in providing reasons for doing or thinking something or seeing it as the most general factive mental state operator[lower-alpha 1].[9] Various theorists are diametrically opposed to the radical reconceptualization and either deny that Gettier cases pose problems or they try to solve them by making smaller modifications to how justification is defined. Such approaches result in a minimal modification of the JTB definition.[1]

Between these two extremes, some philosophers have suggested various moderate departures. They agree that the JTB definition is a step in the right direction: justified true belief is a necessary condition of knowledge. However, they disagree that it is a sufficient condition. They hold instead that an additional criterion, some feature X, is necessary for knowledge. For this reason, they are often referred to as JTB+X definitions of knowledge.[1][34] A closely related approach speaks not of justification but of warrant and defines warrant as justification together with whatever else is necessary to arrive at knowledge.[4][35] Many candidates for the fourth feature have been suggested. In this regard, knowledge may be defined as justified true belief that does not depend on any false beliefs, that there are no defeaters[lower-alpha 2] present, or that the person would not have the belief if it was false.[11][32] Such and similar definitions are successful at avoiding many of the original Gettier cases. However, they often fall prey to newly conceived counterexamples.[8] To avoid all possible cases, it may be necessary to find a criterion that excludes all forms of epistemic luck. It has been argued that such a criterion would set the required standards of knowledge very high: the belief has to be infallible to succeed in all cases.[5][37] This would mean that very few of our beliefs amount to knowledge, if any.[5][8][38] For example, Richard Kirkham suggests that our definition of knowledge requires that the evidence for the belief necessitates its truth.[39] There is still very little consensus in the academic discourse as to which of the proposed modifications or reconceptualizations is correct.[1][8][9]

Propositional knowledge, also referred to as descriptive knowledge, is the paradigmatic type of knowledge in analytic philosophy, and various classifications are used to distinguish between its different subtypes.[4][5][6] The distinctions between the major types are usually drawn based on the linguistic formulations used to express them.[1] 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 Canberra is the capital of Australia".[5][6][8] In this case, Akari stands in the relation of knowing to the proposition "Canberra is the capital of Australia". Closely related types of knowledge are know-wh, for example, knowing where the Taj Mahal is or knowing who killed J. F. Kennedy.[5] These expressions are normally understood as types of propositional knowledge since they usually can be paraphrased using a that-clause.[5][6][40]

Propositional knowledge is either occurrent and dispositional. This mirrors the distinction between occurrent and dispositional beliefs: to know occurrently means to entertain the corresponding representation currently, to be aware of it. "Dispositional knowledge" refers to the mere ability to do so without its execution. In this regard, a person fully immersed in a go-kart race has dispositional but not occurrent knowledge of where their home is. The reason is that they are currently occupied with something else but could easily provide this information if they stopped and focused on it.[6][41][42]

Knowing how to ride a bicycle is one form of non-propositional knowledge.

For non-propositional knowledge, no essential relation to a proposition is involved. The two most well-known forms are knowledge-how (know-how or procedural knowledge) and knowledge by acquaintance.[5][6][7] The term "know-how" refers to some form of practical ability or skill. It can be defined as having the corresponding competence.[5][40] Examples include knowing how to ride a bicycle or knowing how to play the guitar. Some of the abilities responsible for know-how may also involve certain forms of knowledge-that, as in knowing how to prove a mathematical theorem. But this is not generally the case.[9] It is usually argued that mainly humans and maybe other higher animals possess propositional knowledge since it requires an advanced form of mind. Practical knowledge, on the other hand, is more common in the animal kingdom. In this regard, an ant knows how to walk even though it presumably lacks a mind sufficiently developed enough to stand in a relation to the corresponding proposition by representing it.[40]

Knowledge by acquaintance refers to familiarity with an individual that results from direct experiential contact with this individual.[5][6][8] It often, but not exclusively, concerns a relation to a person. On the linguistic level, it does not require a that-clause and can be expressed using a direct object. So when someone claims that they know Wladimir Klitschko personally, they are expressing that they had a certain kind of contact with him and not that they know a certain fact about him. This is usually understood to mean that it constitutes a relation to a concrete individual and not to a proposition. Knowledge by acquaintance plays a central role in Bertrand Russell's epistemology. He contrasts it with knowledge by description, which is a form of propositional knowledge not based on direct perceptual experience.[43][44] So by watching a documentary about Wladimir Klitschko, the viewer may acquire various forms of knowledge by description about him, for example, about his nationality or his career in boxing, without acquiring knowledge by acquaintance of him. However, there is some controversy about whether it is possible to acquire knowledge by acquaintance in its pure non-propositional form. In this regard, some theorists have suggested that it might be better to understand it as one type of propositional knowledge that is only expressed in a grammatically different way.[4]

The distinction between a priori and a posteriori knowledge came to prominence in Immanuel Kant's philosophy and is often discussed in the academic literature. To which category a knowledge attitude belongs depends on the role of experience in its formation and justification.[6][45][46] To know something a posteriori means to know it on the basis of experience.[47][48] For example, to know that it is currently raining or that the baby is crying belongs to a posteriori knowledge since it is based on some form of experience, like visual or auditory experience.[45] A priori knowledge, on the other hand, is possible without any experience to justify or support the known proposition.[46][49] Mathematical knowledge, for example, that 2 + 2 = 4, is a paradigmatic case of a priori knowledge since no empirical investigation is necessary to confirm this fact.[48][49] The distinction between a posteriori and a priori knowledge is usually equated with the distinction between empirical and non-empirical knowledge.[48] This distinction pertains primarily to knowledge but it can also be applied to propositions or arguments. For example, an a priori proposition is a proposition that can be known independently of experience.[45]

The prime example of the relevant experience in question is sensory experience. However, some non-sensory experiences, like memory and introspection, are often included as well. But certain conscious phenomena are excluded in this context. For example, the conscious phenomenon of a rational insight into the solution of a mathematical problem does not make the resulting knowledge a posteriori.[45][46] It is sometimes pointed out that, in a trivial sense, some form of experience is required even for a priori knowledge: the experience needed to learn the language in which the claim is expressed. For a priori knowledge, this is the only form of experience required. For this reason, knowing that "all bachelors are unmarried" is considered a form of a priori knowledge since, given an understanding of the terms "bachelor" and "unmarried", no further experience is necessary to know that it is true.[45][46] One difficulty for a priori knowledge is to explain how it is possible. It is usually seen as unproblematic that one can come to know things through experience but it is not clear how knowledge is possible without experience. One of the earliest solutions to this problem is due to Plato, who argues that, in the context of geometry, the soul already possesses the knowledge and just needs to recollect or remember it to access it again.[49][50] A similar explanation is given by René Descartes, who holds that a priori knowledge exists as innate knowledge present in the mind of each human.[49] A different approach is to posit a special mental faculty responsible for this type of knowledge, often referred to as rational insight or rational intuition.[45]

The distinction between a priori and a posteriori knowledge is closely related to two other distinctions: the distinction between analytic and synthetic propositions and the distinction between necessary and contingent propositions.[45][51][52] Traditionally, it was often assumed that these distinctions coincide. On this view, a priori knowledge concerns propositions that are analytic and necessary while a posteriori knowledge is about propositions that are synthetic and contingent. However, this position is rejected by many contemporary philosophers. One reason is that these distinctions belong to different fields. The a priori–a posteriori distinction belongs to epistemology and is about how one knows things. The analytic–synthetic distinction pertains to semantics and concerns how the meanings of terms make a proposition true. The necessary–contingent distinction is metaphysical and asks, for example, whether a proposition is true in all possible worlds or just in some of them.[45] Various discussions in the academic literature concern the question of how these distinctions overlap or fail to overlap, for example, on cases of synthetic a priori truths or of contingent a priori truths.[45][51][53]

In philosophy, "self-knowledge" usually refers to a person's knowledge of their own sensations, thoughts, beliefs, and other mental states. Many philosophers hold that it is a special type of knowledge since it is more direct than knowledge of the external world, which is mediated through the senses. Traditionally, it was often claimed that self-knowledge is indubitable, for example, that when someone is in pain, they cannot be wrong about this fact. However, various contemporary theorists reject this position. A closely related issue is to explain how self-knowledge works. Some understand it as a form of knowledge by acquaintance while others claim that there is an inner sense that works in analogy to how the external five senses work. According to a different perspective, self-knowledge is indirect in the sense that a person has to interpret their internal and external behavior in order to learn about their mental states, similar to how one can learn about the mental states of other people by interpreting their external behavior.[54][55][56]

In a slightly different sense, the term self-knowledge can also refer to the knowledge of the self as a persisting entity that has certain personality traits, preferences, physical attributes, relationships, goals, and social identities. This meaning is of particular interest to psychology and refers to a person's awareness of their own characteristics.[57][58][59] Self-knowledge is closely related to self-concept, the difference being that the self-concept also includes unrealistic aspects of how a person sees themselves. In this regard, self-knowledge is often measured by comparing a person's self-assessment of their character traits with how other people assess this person's traits.[58]

Situated knowledge is knowledge specific to a particular situation.[60][61] It is closely related to practical or tacit knowledge, which is learned and applied in specific circumstances. This especially concerns certain forms of acquiring knowledge, such as trial and error or learning from experience.[62] In this regard, situated knowledge usually lacks a more explicit structure and is not articulated in terms of universal ideas.[61] The term is often used in feminism and postmodernism to point out that many forms of knowledge are not absolute but depend on the concrete historical, cultural, and linguistic context.[60][61] Understood in this way, it is frequently utilized to argue against absolute or universal knowledge claims stated in the scientific discourse. Donna Haraway is a prominent defender of this position.[62][63] One of her arguments is based on the idea that perception is embodied and is not a universal "gaze from nowhere".[62] Some interpreters associate with this position a form of epistemological relativism because of how knowledge depends on the local conditions of the culture in which it arises.[60][64]

Many forms of eastern spirituality and religion distinguish between higher and lower knowledge. They are also referred to as para vidya and apara vidya in Hinduism or the two truths doctrine in Buddhism. Lower knowledge is based on the senses and the intellect.[65] In this regard, all forms of empirical and objective knowledge belong to this category.[66] Most of the knowledge needed in one's everyday functioning is lower knowledge. It is about mundane or conventional things that are in tune with common sense, like that mice are smaller than elephants. It is relevant to many practical issues, like how to repair a car or how to persuade a customer.[65][67] Scientific knowledge, for example, that the chemical composition of water is H₂O, is often seen as one of the most advanced forms of lower knowledge.[68]

Higher knowledge, on the other hand, is understood as knowledge of God, the absolute, the true self, or the ultimate reality. It belongs neither to the external world of physical objects nor to the internal world of the experience of emotions and concepts. Many spiritual teachings emphasize the increased importance, or sometimes even exclusive importance, of higher knowledge in comparison to lower knowledge. This is usually based on the idea that achieving higher knowledge is one of the central steps on the spiritual path. In this regard, higher knowledge is seen as what frees the individual from ignorance, helps them realize God, or liberates them from the cycle of rebirth.[66][67] This is often combined with the view that lower knowledge is in some way based on a delusion: it belongs to the realm of mere appearances or Maya, while higher knowledge manages to view the reality underlying these appearances.[68] In the Buddhist tradition, the attainment of higher knowledge or ultimate truth is often associated with seeing the world from the perspective of sunyata, i.e. as a form of emptiness lacking inherent existence or intrinsic nature.[65][69][70]

Formal epistemology studies knowledge using formal tools, such as mathematics and logic.[91] An important issue in this field concerns the epistemic principles of knowledge. They are rules governing how knowledge and related states behave and in what relations they stand to each other. The transparency principle, also referred to as the luminosity of knowledge, is an often discussed principle. It states that knowing something implies the second-order knowledge that one knows it. So if Heike knows that today is Monday, then she also knows that she knows that today is Monday.[9][92][93] According to the conjunction principle, having two justified beliefs in two separate propositions implies that the agent is also justified in believing in the conjunction of these two propositions. The closure principle states that if the agent has a justified belief in one proposition and this proposition entails another proposition, then the agent is also justified in believing this other proposition. The evidence transfer principle applies this idea to evidence: if, in the case above, a certain piece of evidence justifies the first belief then it also justifies the second belief.[4]

Sir Francis Bacon, "Knowledge is Power"

The development of the scientific method has made a significant contribution to how knowledge of the physical world and its phenomena is acquired.[94] To be termed scientific, a method of inquiry must be based on gathering observable and measurable evidence subject to specific principles of reasoning and experimentation.[95][96] The scientific method consists of the collection of data through observation and experimentation, and the formulation and testing of hypotheses.[97] Science and the nature of scientific knowledge have also become the subject of philosophy. As science itself has developed, scientific knowledge now includes a broader usage[98] in the soft sciences such as the social sciences. Sir Francis Bacon was critical of the historical development of the scientific method; his works established and popularized an inductive methodology for scientific inquiry. His aphorism, "knowledge is power", is found in the Meditations Sacrae (1597).[99]

Knowledge plays a central role in many religions. Knowledge claims about the existence of God or religious doctrines about how each one should live their lives are found in almost every culture.[100] However, such knowledge claims are often controversial and are commonly rejected by religious skeptics and atheists.[101] The epistemology of religion is the field of inquiry that investigates whether belief in God and in other religious doctrines is rational and amounts to knowledge.[100][102] It is different from other forms of epistemology because of its unique subject matter.[101] One important view in this field is evidentialism. It states that belief in religious doctrines is justified if it is supported by sufficient evidence. Suggested examples of evidence for religious doctrines include religious experiences such as direct contact with the divine or inner testimony as when hearing God's voice.[100][102][103] However, evidentialists often reject that belief in religious doctrines amount to knowledge based on the claim that we lack sufficient evidence.[100][102] A famous saying in this regard is due to Bertrand Russell. When asked how he would justify his lack of belief in God when facing His judgment after death, he replied "Not enough evidence, God! Not enough evidence."[100]

However, religious teachings about the existence and nature of God are not always understood as knowledge claims by their defenders and some explicitly state that the proper attitude towards such doctrines is not knowledge but faith. This is often combined with the assumption that these doctrines are true but cannot be fully understood by reason or verified through rational inquiry. For this reason, it is claimed that one should accept them even though they do not amount to knowledge.[101] Such a view is reflected in a famous saying by Immanuel Kant where he claims that he "had to deny knowledge in order to make room for faith."[104]

Distinct religions often differ from each other concerning the doctrines they proclaim as well as their understanding of the role of knowledge in religious practice.[105][106] Knowledge plays a central role in Abrahamic religions.[107] In Jewish tradition, knowledge (Hebrew: דעת da'ath) is considered one of the most valuable traits a person can acquire. Observant Jews recite three times a day in the Amidah "You favor people with knowledge and teach mortals understanding. Favor us with your knowledge, understanding, and wisdom. Blessed are you, Adonai, who favors people with knowledge."[108][109][110] The Tanakh states, "A wise man is strong; yes, a man of knowledge grows in strength."[111] The Old Testament's tree of the knowledge of good and evil contained the knowledge that separated Man from God: "And the LORD God said, Behold, the man is become as one of us, to know good and evil..." (Genesis 3:22)

In many expressions of Christianity, such as Catholicism[112] and Anglicanism,[113] knowledge is one of the seven gifts of the Holy Spirit. As Pope Francis points out, "the knowledge that comes from the Holy Spirit, however, is not limited to human knowledge; it is a special gift, which leads us to grasp, through creation, the greatness and love of God and his profound relationship with every creature."[114]

In Islam, knowledge (Arabic: علم, ʿilm) is given great significance. "The Knowing" (al-ʿAlīm) is one of the 99 names reflecting distinct attributes of God. The Qur'an asserts that knowledge comes from God (2:239) and various hadith encourage the acquisition of knowledge. Muhammad is reported to have said "Seek knowledge from the cradle to the grave" and "Verily the men of knowledge are the inheritors of the prophets". Islamic scholars, theologians and jurists are often given the title alim, meaning "knowledgeble".[115]

In Gnostic beliefs, everyone is said to possess a piece of the highest good or Ultimate God deep within themselves that had fallen from the spiritual world into the bodies of humans, sometimes called a divine spark. It is trapped in their material bodies created by the inferior God or Demiurge unless secret knowledge from the outside universe called gnosis is achieved. The one who brings such knowledge is considered the savior or redeemer.[116]

Saraswati is the goddess of knowledge and the arts in Hinduism.

Hindu Scriptures present two kinds of knowledge, Paroksh Gyan and Prataksh Gyan. Paroksh Gyan (also spelled Paroksha-Jnana) is secondhand knowledge: knowledge obtained from books, hearsay, etc. Pratyaksh Gyan (also spelled Pratyaksha-Jnana) is the knowledge borne of direct experience, i.e., knowledge that one discovers for oneself.[117] Knowledge is of special importance in the classical path of Hinduism known as jnana yoga or path of knowledge. Its aim is to achieve oneness with the divine by fostering an understanding of the self and its relation to Brahman or ultimate reality.[118][119]

According to the Jain texts like Tattvārthsūtra and Sarvārthasiddhi, there are five kinds of knowledge: sensory knowledge, scriptural knowledge, clairvoyance, telepathy, and omniscience (Mati Jñāna, Śruta Jñāna, Avadhi Jñāna, Manah prayāya, and Kevala Jnana). The first two kinds are regarded as indirect knowledge since the soul depends on the sense and the mind to acquire them. This is not the case for the remaining three kinds, which constitute direct knowledge.[120]

The anthropology of knowledge is a multi-disciplinary field of inquiry.[121][122] It studies how knowledge is acquired, stored, retrieved, and communicated.[123] Special interest is given to how knowledge is reproduced and undergoes changes in relation to social and cultural circumstances.[121] In this context, the term knowledge is used in a very broad sense, roughly equivalent to terms like understanding and culture.[121][124] This means that the forms and reproduction of understanding are studied irrespective of their truth value. In epistemology, on the other hand, knowledge is usually restricted to forms of true belief. The main focus in anthropology is on empirical observations of how people ascribe truth values to meaning contents, like when affirming an assertion, even if these contents are false.[121] But it also includes practical components: knowledge is what is employed when interpreting and acting on the world and involves diverse phenomena, such as feelings, embodied skills, information, and concepts. It is used to understand and anticipate events in order to prepare and react accordingly.[124]

The reproduction of knowledge and its changes often happen through some form of communication.[121][123] This includes face-to-face discussions and online communications as well as seminars and rituals. An important role in this context falls to institutions, like university departments or scientific journals in the academic context.[121] A tradition may be defined as knowledge that has been reproduced within a society or geographic region over several generations. However, societies also respond to various external influences, such as other societies, whose understanding is often interpreted and incorporated in a modified form.[121][124]

An important finding is that individuals belonging to the same social group usually understand things and organize knowledge in similar ways to one another. In this regard, social identities play a significant role: individuals who associate themselves with similar identities, like age-influenced, professional, religious, and ethnic identities, tend to embody similar forms of knowledge.[121][125]