Knowledge
Knowledge is the cognitive relation a subject bears to a proposition when the subject believes the proposition, the proposition is true, and the belief is justified, though this tripartite analysis has faced significant challenges.[1] Originating in ancient philosophy, particularly Plato's exploration in works like the Theaetetus, the concept centers on distinguishing reliable cognition from mere true opinion or unfounded belief. Epistemology examines the sources of knowledge—such as sensory perception, rational inference, memory, and testimony—and debates whether justification requires infallible foundations or arises from coherent belief networks or reliable processes attuned to causal structures.[2] Edmund Gettier's 1963 counterexamples revealed cases of justified true belief undermined by luck, prompting alternatives like reliabilism, which prioritizes beliefs produced by truth-conducive mechanisms over internalist justification.[1] Knowledge manifests in forms including propositional ("knowing that"), procedural ("knowing how"), and by acquaintance, with empirical studies underscoring its adaptive value in predicting environmental contingencies. Ongoing controversies highlight the absence of consensus, as theories like foundationalism, positing self-justifying basic beliefs, compete with coherentism's holistic mutual support, reflecting tensions between evidential standards and real-world belief acquisition.[3]Core Concepts
Definitions of Knowledge
The English term "knowledge" originates from the Middle English "knowleche" or "knaweleche," derived from the verb "knowen" meaning "to know" combined with an element akin to "-leche," related to acknowledgment or recognition, tracing back to Old English "cnāwan" signifying "to recognize" or "to perceive."[4] This etymology emphasizes an active process of cognition or acquaintance with facts or objects.[5] In ordinary usage, knowledge denotes information, facts, skills, or awareness acquired through experience, learning, or education, often distinguished from mere opinion by its basis in evidence or reliability.[6] For instance, knowing how to ride a bicycle involves procedural competence rather than abstract proposition, while knowing that the Earth orbits the Sun requires factual correspondence to observable reality.[7] Philosophically, the dominant traditional analysis defines knowledge as justified true belief (JTB), a formulation attributed to Plato in his dialogue Theaetetus, where he proposes that knowledge is true belief accompanied by an account or justification, distinguishing it from mere true opinion that could arise by luck.[7] Under JTB, a subject S knows a proposition p if: (1) p is true, (2) S believes p, and (3) S is justified in believing p.[8] This tripartite structure prevailed in Western epistemology for over two millennia until Edmund Gettier's 1963 paper presented counterexamples—cases of justified true beliefs that intuitively fail to constitute knowledge due to epistemic luck, such as beliefs true by coincidence rather than reliable cognitive processes.[1] Post-Gettier reforms have proposed alternatives, including the requirement that justification track truth (no false lemmas in the justification chain) or that knowledge entails belief produced by a reliable belief-forming mechanism, as in reliabilist theories.[8] Some epistemologists defend refined versions of JTB, arguing that proper fourth conditions—such as defeatability or causal connection to the fact—resolve Gettier cases without abandoning the core analysis.[8] These debates highlight that no consensus definition exists, with knowledge often characterized minimally as a species of cognitive success involving accurate representation of reality, but varying accounts prioritize factors like internalist justification versus externalist reliability.[7] Empirical studies in cognitive science, such as folk epistemology surveys, indicate that lay intuitions align more closely with JTB augmented by anti-luck conditions than pure reliabilism.[9]Traditional Analysis: Justified True Belief
The traditional analysis of knowledge holds that a subject S knows a proposition p if and only if p is true, S believes p, and S is justified in believing p. This tripartite structure, known as justified true belief (JTB), dominated epistemological thought for centuries, providing a framework to distinguish knowledge from mere opinion or accident.[10] The conditions are individually necessary and jointly sufficient, meaning the absence of any one precludes knowledge, while their conjunction establishes it.[11] Plato first articulated a version of this analysis in his dialogue Theaetetus, composed around 369 BCE, where Socrates proposes that knowledge is "true belief with an account" (logos), interpreted as requiring justification beyond mere truth and belief to ensure reliability.[12] In the text, at sections 201c-d, Plato distinguishes knowledge from true judgments lacking rational explanation, emphasizing that justification elevates belief to knowledge by connecting it causally to the facts via reason.[7] This formulation addressed earlier Socratic concerns with unstable opinions, as seen in the Meno, where true belief without fixation (justification) is deemed unstable and insufficient for genuine understanding. The truth condition stipulates that for S to know p, p must correspond to reality; false beliefs, even if sincerely held and justified, cannot constitute knowledge, as they fail to track actual states of affairs.[10] The belief condition requires that S actually hold p in mind as accepted, excluding cases where S lacks conviction, such as unwitting truths or denials of evident facts.[11] Justification demands that S's belief be supported by sufficient evidence or reasoning, typically evidentialist in nature, where the grounds causally explain the belief's reliability rather than mere psychological comfort.[7] Proponents argued this prevents lucky guesses, as in scenarios where a subject correctly identifies a distant figure as a sheep due to misleading evidence that coincidentally aligns with truth, lacking proper justificatory linkage.[10] This analysis influenced Western philosophy from antiquity through the early 20th century, underpinning accounts in thinkers like Descartes, who sought indubitable justification via clear and distinct perceptions, and Locke, who emphasized empirical evidence as the basis for justified beliefs about the external world.[7] By formalizing knowledge as JTB, it enabled rigorous analysis of epistemic norms, prioritizing causal connections between belief-forming processes and truth over subjective confidence alone.[12]Modern Challenges and Reforms
In 1963, Edmund Gettier published "Is Justified True Belief Knowledge?", presenting counterexamples that undermine the sufficiency of justified true belief (JTB) for knowledge.[13] These cases involve a subject holding a true belief with apparent justification, yet the belief's truth arises coincidentally through luck or misleading evidence, such as inferring a false lemma that happens to connect to a true conclusion.[13] For instance, if Smith justifiably believes Jones owns a Ford based on evidence, and believes "the man who will get the job has ten coins in his pocket" due to Jones's situation, but Smith himself gets the job and has ten coins unbeknownst to him, the belief qualifies as JTB without intuitive knowledge.[13] Gettier problems highlight how justification can decouple from truth-tracking, prompting widespread rejection of JTB as an adequate analysis among analytic epistemologists by the late 20th century.[14] One prominent reform is reliabilism, advanced by Alvin Goldman in works from 1976 onward, which defines knowledge as a true belief produced by a reliable belief-forming process— one that yields truth with high probability across counterfactual applications.[15] Process reliabilism avoids Gettier cases by requiring causal reliability rather than internal justification; for example, perceptual beliefs formed by functioning senses count as knowledge if the process reliably tracks environmental facts, irrespective of the subject's reflective access to its reliability.[15] Critics argue it struggles with "swampman" scenarios, where a duplicate entity forms identical true beliefs without a reliable history, or with clairvoyance cases yielding truths sans causal link.[14] Nonetheless, variants like safety-based reliabilism, emphasizing beliefs' resistance to nearby error possibilities, persist in contemporary epistemology.[14] Virtue epistemology, developed by figures like Ernest Sosa since the 1980s, reconceives knowledge in terms of intellectual virtues—reliable dispositions such as careful reasoning or perceptual acuity—such that a true belief manifests the agent's epistemic competence in appropriate conditions.[16] This approach integrates reliabilist elements by viewing virtues as safety-conferring faculties, addressing Gettier luck through demands for "animal knowledge" (first-order reliability) elevated to "reflective knowledge" via higher-order awareness of one's competence.[16] Proponents claim it aligns with intuitive attributions of knowledge, as in expert testimony where skill overrides accidental truth.[16] Detractors note potential over-intellectualization, as everyday knowledge often lacks explicit virtue reflection, and challenges in distinguishing virtues from mere reliable processes.[16] Contextualism offers another response, positing that "knowledge" attributions vary by conversational context, with stricter standards (e.g., ruling out skeptical hypotheses) in philosophical discourse but looser ones in practical settings.[14] Keith DeRose's 1995 framework treats epistemic justification as context-sensitive, allowing JTB to hold in low-stakes contexts while Gettier-like intuitions arise only under heightened scrutiny.[14] This resolves paradoxes without altering core conditions but faces empirical pushback from ordinary language studies showing inconsistent shifts in knowledge ascriptions across stakes.[14] Despite these reforms, no post-Gettier theory commands consensus; debates continue over whether knowledge admits reductive analysis or requires primitive status, with ongoing empirical work in experimental philosophy testing folk intuitions against proposals.[14]Types and Distinctions
Propositional Knowledge
Propositional knowledge, often termed knowledge-that, consists of justified beliefs in propositions—declarative statements that possess a truth value, such as "Water boils at 100 degrees Celsius at sea level under standard atmospheric pressure."[7] This type of knowledge is central to epistemology, as it involves grasping facts or truths about the world, distinguishable by its embeddability under "that"-clauses in natural language. For example, a person knows propositionally that the Battle of Thermopylae occurred in 480 BCE if their belief aligns with historical evidence, such as Herodotus's accounts corroborated by archaeological findings from the pass.[17] Unlike procedural knowledge, which entails skills like swimming or solving quadratic equations through practice, propositional knowledge does not require demonstrable ability but rather cognitive assent to verifiable truths.[18] Gilbert Ryle, in The Concept of Mind (1949), critiqued conflating the two, arguing that knowing that one can swim differs causally from the embodied competence itself, with propositional claims failing to capture motoric expertise.[19] Empirical studies, such as those on expertise acquisition, support this by showing that factual recall (propositional) correlates weakly with performance proficiency in domains like chess, where grandmasters excel via pattern recognition over explicit rule recitation.[18] Historically, the analysis of propositional knowledge traces to Plato's Meno (c. 380 BCE), where Socrates posits it as true belief stabilized by an account or reason, distinguishing it from mere opinion, as illustrated by the jury example: correct verdicts without rationale remain unstable and non-transmissible.[17] This framework influenced subsequent philosophy, emphasizing propositional knowledge's role in rational inquiry, though modern epistemology debates its sufficiency amid Gettier-style counterexamples involving lucky justifications. Within propositional knowledge, subtypes include empirical propositions derived from observation (e.g., "The boiling point of water is 100°C") and logical ones from deduction (e.g., "All bachelors are unmarried").Non-Propositional Knowledge
Non-propositional knowledge, also designated as knowledge-how or procedural knowledge, consists of abilities to execute actions or deploy skills competently, independent of articulating underlying facts as propositions. This contrasts with propositional knowledge, which involves true beliefs about states of affairs that can be expressed declaratively. For instance, an individual may possess the non-propositional knowledge required to swim fluidly across a pool through repeated immersion and adjustment, even if unable to enumerate the precise biomechanics involved./07:_Epistemology/7.01:_What_Epistemology_Studies)[18] Philosopher Gilbert Ryle advanced the distinction in his 1946 presidential address, positing that practical intelligence—manifested in "knowing how" to perform tasks like tying knots or debating effectively—precedes and escapes reduction to theoretical "knowing that" claims. Ryle rejected the intellectualist doctrine, which he termed a "legend," asserting it conflates episodic propositional grasp with the dispositional capacities enabling skillful conduct across varied circumstances. He illustrated this by noting that a book of rules for intelligent play, such as in chess, does not equip one to play unless one already knows how to apply them, revealing a foundational layer of non-propositional competence.[20][21] Subsequent epistemological inquiry has contested whether knowledge-how fully dissociates from propositional elements. Anti-intellectualists maintain it constitutes irreducible dispositions or abilities, evaluable by success in action rather than truth-apt content. Conversely, intellectualist accounts, advanced since the early 2000s, propose that genuine knowledge-how equates to propositional knowledge of methods under a "practical mode of presentation," where one knows factively that one possesses the relevant capacity. Empirical evidence from cognitive science, including studies on skill acquisition via motor learning, supports the view that non-propositional knowledge emerges through iterative feedback loops, bypassing explicit rule formulation.[22][23] Examples abound in everyday domains: cycling balances intuitive adjustments to weight shifts, unverbalizable without loss of essence; similarly, expert musicians improvise harmonies attuned to tonal contexts, drawing on ingrained patterns rather than sequential propositional deductions. Such knowledge resists exhaustive propositional encoding, as attempts to verbalize it often yield approximations that fail to transmit proficiency—evident in the inefficacy of mere instructions for acquiring dance steps or surgical techniques without embodied practice. This underscores non-propositional knowledge's role in causal efficacy, where it directly informs behavior absent mediating beliefs.[24][25]A Priori versus A Posteriori Knowledge
A priori knowledge derives its justification from rational insight independent of sensory experience, whereas a posteriori knowledge relies on empirical evidence obtained through observation or experimentation.[26] [27] This distinction addresses how propositions are known to be true: a priori propositions, such as basic logical or mathematical statements, hold necessarily and universally without requiring verification against particular instances in the world.[28] In contrast, a posteriori propositions are contingent, their truth depending on specific causal interactions with the environment, as confirmed by repeatable tests or direct perception.[27] The terms originated in medieval philosophy but gained prominence through Immanuel Kant's Critique of Pure Reason, first published in 1781, where he used them to classify judgments based on their epistemic origins.[26] Kant argued that a priori knowledge underpins synthetic judgments—those that extend beyond definitional tautologies—such as the principles of causality or the structure of space and time, which he posited as innate frameworks enabling experience rather than derived from it.[26] For instance, the proposition "every event has a cause" is synthetic a priori for Kant, necessary for coherent empirical inquiry but not empirically derived.[26] A posteriori knowledge, by comparison, includes scientific generalizations like "water boils at 100°C under standard atmospheric pressure," which hold only as inductive approximations subject to falsification by counterexamples.[29] Classic examples illustrate the divide: a priori cases include "all bachelors are unmarried," justified by conceptual analysis alone, or "7 + 5 = 12," grasped through pure arithmetic without physical counting.[28] [29] A posteriori examples encompass "the 2024 U.S. presidential election was held on November 5," verifiable only through historical records, or "saltwater conducts electricity," established via laboratory experiments measuring resistance under controlled conditions.[27] These distinctions align with broader debates in epistemology, where rationalists like Kant emphasize a priori foundations for certainty, while empiricists prioritize a posteriori methods for reliability, often viewing apparent a priori truths as shorthand for deeply ingrained experiential patterns.[26] Challenges to the distinction emerged in the 20th century, notably from W.V.O. Quine in his 1951 essay "Two Dogmas of Empiricism," which rejected the related analytic-synthetic divide underpinning much a priori justification.[30] Quine contended that no statement is immune to revision based on empirical data, arguing that even logical laws like the law of non-contradiction could be adjusted holistically if confronted with recalcitrant evidence, such as anomalous observations in quantum mechanics.[31] [30] This holism implies a spectrum rather than a binary, with purported a priori knowledge embedded in a web of beliefs tested collectively against the world, undermining claims of absolute independence from experience.[31] Defenders of a priori knowledge counter that Quine's view conflates justification with revisability; mathematical proofs, for example, retain apodictic certainty absent empirical refutation, as their validity stems from deductive chains insulated from sensory variance.[32] Empirical studies in cognitive science provide indirect support for the distinction's utility. Developmental psychology shows infants exhibiting sensitivity to numerical quantities around 5 months of age, suggesting innate a priori-like capacities for basic arithmetic before extensive experience, as demonstrated in violation-of-expectation paradigms where unexpected numerosity leads to longer gaze times.[29] Conversely, a posteriori knowledge accumulates through causal learning, such as associating lever-pulling with food rewards in animal conditioning experiments, where reinforcement schedules dictate belief formation rates—e.g., variable-ratio schedules yielding higher response persistence than fixed ones, per Skinner's 1938 data.[27] These findings highlight causal realism: a priori elements may structure cognition universally, but a posteriori processes adapt to environmental contingencies, with neither fully reducible to the other. The persistence of the distinction in philosophy reflects its explanatory power, despite Quinean skepticism, as it delineates domains where reason yields necessity versus where observation reveals contingency.Explicit versus Tacit Knowledge
The distinction between explicit and tacit knowledge originates with philosopher Michael Polanyi, who introduced the concept of tacit knowledge in his 1958 book Personal Knowledge and elaborated it in The Tacit Dimension (1966), arguing that much human cognition relies on subsidiary awareness that cannot be fully articulated.[33] Tacit knowledge refers to intuitive, context-dependent understanding acquired through experience, such as the skill of balancing while riding a bicycle, which defies complete verbal description despite conscious recognition of the ability.[34] Polanyi famously encapsulated this as "we can know more than we can tell," highlighting how subsidiary clues—like bodily sensations or pattern recognition—underpin focal awareness without being explicitly formulable.[35] Explicit knowledge, by contrast, consists of information that is codified, formalized, and readily communicable, such as mathematical equations, technical manuals, or database entries that can be stored and transferred without loss of meaning.[36] It is characterized by its articulability and independence from personal context, enabling efficient dissemination through written or digital media, as seen in scientific formulas or procedural instructions.[37] Unlike tacit knowledge, explicit forms do not require direct experience for comprehension, though their application often draws on tacit elements for practical efficacy.[38] The two forms interact dynamically: explicit knowledge can serve as a scaffold for tacit acquisition, while tacit insights often drive the generation of new explicit articulations, as in scientific discovery where intuitive hunches precede formal proofs.[35] In epistemological terms, this dichotomy challenges reductionist views of knowledge as solely propositional, emphasizing tacit dimensions in skills (know-how), recognition (knowing a face), and judgment (e.g., a clinician's diagnostic intuition).[39] Empirical studies in fields like expertise development confirm that tacit knowledge accumulates via apprenticeship and practice, resisting full codification due to its embodied and situational nature.[34] Transferring tacit knowledge thus demands social processes like observation and mentorship, rather than mere documentation, underscoring limitations in purely informational models of epistemology.[40]| Aspect | Explicit Knowledge | Tacit Knowledge |
|---|---|---|
| Articulability | Easily expressed in words, symbols, or code | Difficult or impossible to fully verbalize |
| Acquisition | Through instruction, reading, or data access | Via experience, practice, and immersion |
| Transfer | Direct via documents or teaching | Indirect through demonstration and interaction |
| Examples | Recipes, algorithms, legal statutes | Riding a bike, facial recognition, craft skills |