Epistemic

Epistemic is an adjective describing matters related to knowledge, its sources, and the justification of beliefs. The term derives from the Greek epistēmē, meaning knowledge or understanding, and is used across philosophy, linguistics, statistics, and related fields to distinguish knowledge-related phenomena from other types of claims.

In philosophy, epistemic concerns are central to epistemology, the study of knowledge. Epistemic concepts address how beliefs are justified, what counts as evidence, and how certainty is achieved or undermined. The label “epistemic” is used to classify claims, processes, or standards that pertain to knowledge rather than to the external world itself (ontic claims). Terms such as epistemic justification, epistemic rationality, and epistemic virtue describe how agents should form and revise beliefs.

In linguistics and cognitive science, epistemic relates to modality—how statements express the speaker’s degree of certainty or evidential basis. Epistemic modality is conveyed through verb forms, adverbs, and intonation, as in sentences that indicate possibility, probability, or certainty. Epistemic verbs (know, believe, suppose) and epistemic adverbs (probably, perhaps, allegedly) signal the speaker’s knowledge state.

In statistics and decision theory, epistemic uncertainty denotes uncertainty arising from incomplete knowledge about a system or model, which could be reduced by gathering more information or refining models. This is contrasted with aleatory uncertainty, which stems from inherent randomness and cannot be eliminated by further study.

In artificial intelligence and machine learning, epistemic uncertainty is often distinguished from data-related (aleatory) uncertainty and informs approaches to active learning, model refinement, and data acquisition to improve decision making.