The label Vijñānavāda (consciousness school) was applied to the epistemological and ontological positions of the YogĀcĀra school and the Buddhist logic tradition in the polemical debate literature of their medieval Indian opponents. These Buddhist and non-Buddhist disputants used the term vijñānavāda to emphasize the Yogācāra assertion that external objects do not exist, but consciousness does, thus inviting an idealist interpretation that these opponents (especially the realist schools, such as Nyāya, Mīmāṃsikā, and SautrĀntika) refuted at great length. Aspects of Buddhist epistemology associated with the Vijñānavāda position include claims that parts, not wholes, are real; claims that particulars are real, not universals; the notion of momentariness; and the assertion that sense-objects (viṣaya), because they appear only within cognitive acts, are not external to the consciousness in which they appear.
The term Vijñānavāda was a misnomer because Yogācāra epistemology actually claimed that while cognitive objects (viṣaya) appearing in consciousness were real, the thing-itself (vastu)—which is singular, momentary, and causally produced—was not apprehended by ordinary perception. Yogācāra denies the realist claim that the perceptible object (viṣaya) has a corresponding vastu as its referent (artha), since a referent, whether perceptual or linguistic, is always a cognitive construction. However, once the consciousness stream is purified of emotional and cognitive obstructions (kleśāvaraṇa and jñeyāvaraṇa, respectively), a vastu can be cognized by direct, immediate cognition (jñāna), unmediated by cognitive, conceptual overlays (prapañca, kalpanā, parikalpita). This type of cognition is called nirvikalpa (devoid of conceptual construction).
Shastri, D. N. The Philosophy of Nyāya-Vaiśeṣika and Its Conflict with the Buddhist Dignāga School (Critique of Indian Realism). Reprint, New Delhi: Bharatiya Vidyā Prakashan, 1976.
Stcherbatsky, F. Theodore. Buddhist Logic (1930), 2 vols. Reprint, New York: Dover, 1962.