Within the Nyāya tradition, inference (anumāna) is honored as one of the principal means of valid knowledge (pramāṇa), standing alongside perception, comparison, and verbal testimony. It functions especially where the senses cannot directly reach, enabling knowledge of what is unperceived through what is perceived. Inference is defined as knowledge that arises from the perception of a mark (liṅga or hetu) that is invariably connected with what is to be known (sādhya), grounded in an invariable concomitance (vyāpti) between them. In this way, inference becomes a disciplined bridge from the seen to the unseen, from immediate experience to a more comprehensive understanding of reality.

Nyāya gives this process a highly structured logical form, traditionally expressed through a five-member syllogism. The movement begins with a proposition (pratijñā), supported by a reason (hetu), illustrated through an example (dṛṣṭānta or udāharaṇa), then applied to the case at hand (upanaya), and finally brought to a conclusion (nigamana). This careful unfolding of thought is not mere formalism; it is meant to make each step of reasoning transparent and open to examination. By insisting that each link in the chain be explicit, Nyāya turns inference into a shared, testable pathway toward truth rather than a private leap of intuition.

For such inference to be valid, the relation of vyāpti between the reason and what is to be established must be secure. This relation is expected to be free from known counterexamples, grounded in adequate observation, and supported by sound reasoning. Nyāya thinkers therefore devote considerable attention to identifying fallacious reasons (hetvābhāsa), so that spurious inferences can be exposed and set aside. Through this vigilance, inference becomes not only a means of discovery but also a tool for cleansing thought of error and confusion.

The scope of inference in this system is wide, extending from everyday judgments to subtle philosophical claims. It encompasses reasoning from cause to effect, from effect back to cause, and through more general correlations that are neither strictly causal nor purely particular. In this way, inference allows reflection on past and future events, on causal structures, and on entities that lie beyond immediate perception. For a seeker within the Nyāya framework, inference thus serves as a disciplined inner dialogue: a methodical, logically articulated ascent from scattered experiences toward a more ordered and reliable vision of what is real.