Dignāga (also known as Diṅnāga, c. 470/480 – c. 530/540 CE) was an Indian Buddhist philosopher and logician. He is credited as one of the Buddhist founders of Indian logic (hetu vidyā) and atomism. Dignāga's work laid the groundwork for the development of deductive logic in India and created the first system of Buddhist logic and epistemology (pramāṇa).

According to Georges B. Dreyfus, his philosophical school brought about an Indian "epistemological turn" and became the "standard formulation of Buddhist logic and epistemology in India and Tibet." Dignāga's thought influenced later Buddhist philosophers like Dharmakīrti and also Hindu thinkers of the Nyāya school. Dignāga's epistemology accepted only "perception" (pratyaksa) and "inference" (anumāṇa) as valid instruments of knowledge and introduced the widely influential theory of "exclusion" (apoha) to explain linguistic meaning. His work on language, inferential reasoning and perception were also widely influential among later Indian philosophers. According to Richard P. Hayes "some familiarity with Dinnaga's arguments and conclusions is indispensable for anyone who wishes to understand the historical development of Indian thought."

Little is known about Dignāga's life. According to Taranatha, Dignāga was born to a Brahmin family near the city of Kanchi in around 470 or 480 CE and was ordained into the Vātsīputrīya order at an early age by a monk named Nāgadatta. Xuanzang states that Dignāga was active for a period in the "Andhra country". At some point in his life, Dignāga became associated with the monastery of Nalanda.

Dignāga's mature philosophy is expounded in his magnum opus, the Pramāṇa-samuccaya. In chapter one, Dignāga explains his epistemology which holds that there are only two 'instruments of knowledge' or 'valid cognitions' (pramāṇa); "perception" or "sensation" (pratyakṣa) and "inference" or "reasoning" (anumāna). In chapter one, Dignāga writes:

Sensation and reasoning are the only two means of acquiring knowledge, because two attributes are knowable; there is no knowable object other than the peculiar and the general attribute. I shall show that sensation has the peculiar attribute as its subject matter, while reasoning has the general attribute as its subject matter.

Perception is a non-conceptual knowing of particulars which is bound by causality, while inference is reasonable, linguistic and conceptual. This conservative epistemic theory was in contrast to the Nyāya school who accepted other means of knowledge such as upamāna (comparison and analogy).

Pratyakṣa is a kind of awareness that acquires information about particulars, and is immediately present to one of the senses. This is the topic of the first chapter of the Pramāṇa-samuccaya. For Dignāga, perception is pre-verbal, pre-conceptual and unstructured sense data. In chapter two of the Pramāṇa-samuccaya he writes:

Sensation is devoid of structure. That cognition in which there is no structure is sensation. What kind of thing is this so-called structure? Attaching a name, a universal and so forth.