nonobservational

Nonobservational is an adjective used in science, philosophy of science, and related disciplines to describe things that are not directly accessible to sensory perception or measurement. In general, observational phenomena are those that can be detected or verified through sense data or instrumental readings. Nonobservational refers to entities, data, terms, or statements that rely on inference, theory, or modeling rather than direct observation.

In scientific practice, nonobservational elements often function as theoretical constructs. Examples include subatomic particles (such as electrons or quarks), dark matter, or early-universe conditions, which are not observed directly in the sense data but are inferred from patterns, experiments, and predictive success of theories. The status of nonobservational concepts is typically evaluated by how well they explain observations, predict new phenomena, and fit within a coherent theoretical framework.

In philosophy of science, the distinction between observational and nonobservational language is used to discuss how scientific theories reference the world. Observational terms are thought to pick out directly detectable features of experience, while nonobservational or theoretical terms refer to unobservables that are posited to explain observations. Debates in this area address issues such as realism about unobservables, the justificatory role of inference, and the evidential standards for accepting nonobservational entities.

See also: observational terms, theoretical terms, scientific realism, instrumentalism, unobservable entities.