Dignāga

• 1. Introduction

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  Dignaga asked a question that cuts to the heart of what it means to know anything at all: how can we be certain that what we sense, what we reason, and what we say in words actually reflects reality? Born around 470 or 480 CE near the city of Kanchi, this Indian Buddhist philosopher and logician spent his life building the first systematic answer Buddhist thought had ever produced. He would go on to be credited as one of the founding figures of Indian logic itself, a tradition called hetu vidya. His magnum opus, the Pramana-samuccaya, became the standard reference for Buddhist logic and epistemology across India and Tibet. According to the scholar Richard P. Hayes, some familiarity with Dignaga's arguments is indispensable for anyone who wants to understand how Indian thought developed. What was the framework he built? How did he decide what counts as genuine knowledge? And why did his ideas force every subsequent Indian philosopher, Buddhist or not, to defend their beliefs on entirely new terms?

• 2. A Life in Fragments

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  The historian Taranatha records that Dignaga was born to a Brahmin family near Kanchi, one of the important cities of the Indian south. At an early age he was ordained into the Vatsiputriya order by a monk named Nagadatta. Beyond these sparse details, the record grows thin. The Chinese pilgrim Xuanzang adds that Dignaga spent a period active in the Andhra country. At some point he became associated with the great monastery of Nalanda. No precise dates mark his travels or his major compositions. What survives are the ideas he left behind, preserved not in the original Sanskrit but in Tibetan and Chinese translations whose translators, as Hayes notes, were not always certain of his meaning. That uncertainty has shaped how scholars have read him ever since, sometimes blurring the line between what Dignaga actually wrote and what later thinkers added in his name.

• 3. Two Windows on the World

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  At the opening of the Pramana-samuccaya, Dignaga states his core position in direct terms: "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." Perception, which he calls pratyaksa, deals with particulars. Inference, which he calls anumana, deals with general attributes. By limiting valid knowledge to exactly these two instruments, Dignaga broke from the Nyaya school, which accepted other sources of knowledge including comparison and analogy, a method called upamana. The reduction was deliberate. Each of the two instruments has a distinct object, a distinct mode of operation, and for Dignaga, a distinct boundary it cannot cross without distorting reality.

• 4. The Pure Moment of Sensation

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  Pratyaksa, for Dignaga, is something almost brutally simple. In chapter two of the Pramana-samuccaya he writes: "Sensation is devoid of structure. That cognition in which there is no structure is sensation." The moment our mind begins to attach a name, a universal category, or a comparison to past experience, we have already left sensation behind. Dignaga calls this structuring process kalpana. What pratyaksa actually delivers is awareness of particulars: a patch of green color, the sensation of hardness. Never an apple, which is already a higher-level synthesis the mind has constructed. Dignaga goes further and argues that sensation is inerrant. As he puts it, "it is impossible too for the object of awareness itself to be errant, for errancy is only the content of misinterpretation by the mind." Pratyaksa is also private and inexpressible, and it does not depend on the existence of an external world to be real as an experience.

• 5. The Logic of Signs

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  Inference builds on sensation but operates by completely different rules. Dignaga's central example is the relationship between smoke and fire: observing smoke leads a reasoner to infer fire. But for that inference to be legitimate, three conditions must hold. The inferential sign, such as the smoke, must be a property of the subject being examined. It must be known to occur in at least one case where the inferred property also occurs. And it must not be known to occur in any case where the inferred property is absent. Chapter two of the Pramana-samuccaya addresses inference for one's own use, which Dignaga calls svartha-anumana. Chapter three turns to demonstration for others, pararthanumana, the question of how a reasoner communicates a valid inference through argument. Richard Hayes reads the three-condition test as extraordinarily demanding. In Hayes's interpretation, Dignaga's logic functions as a practice of rational skepticism, a way of embodying the Buddhist principle of not clinging to views. Hayes quotes the consequence directly: since no evidence exists for any fully omniscient being, the best working hypothesis is that no one's thinking is immune from errors requiring revision when new realities emerge.

• 6. Words and What They Exclude

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  Language presented Dignaga with a particular puzzle. The Nyaya school and Hindu Sanskrit grammarians such as Bhartrhari had developed their own accounts of meaning, but both traditions generally accepted the reality of universals, a concept most Buddhist philosophers rejected. The Sautrantika school had already pushed toward nominalism, using the term prajnapti. Dignaga went a step further with his theory of apoha, or exclusion. The scholar Hattori Masaaki explains it this way: a word indicates an object merely through the exclusion of other objects. The word "cow" means only that the object is not a non-cow. No word, on this account, can directly denote anything real, whether an individual, a universal, or anything else. Dignaga treats this kind of linguistic meaning as a special case of inference, not a separate instrument of knowledge. He takes up these issues in chapter five of the Pramana-samuccaya. Kumarila Bhatta, in his Shlokavartika, wrote a direct response to Dignaga's criticism of Mimamsa Sutra 1.1.4, which shows that his arguments were taken seriously enough to require formal refutation.

• 7. The School He Founded

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  Georges B. Dreyfus describes what Dignaga set in motion as an Indian "epistemological turn." After Dignaga, Indian philosophers of all schools were expected to ground their positions in a fully developed epistemological theory. The school he founded is sometimes called the School of Dignaga, sometimes the School of Dignaga and Dharmakirti, and in Tibetan tradition those who follow reasoning. In modern scholarship the Sanskrit term pramana-vada, often translated as the Epistemological School, is commonly used. Dignaga's logic and epistemology spread into the Madhyamaka tradition through figures such as Bhavaviveka, active around 500 CE, and Santaraksita, who lived from around 725 to 788 CE. In Tibet the tradition was extended by thinkers including Cha-ba and Sakya Pandita, both active in the period around 1182 to 1251. Lawrence J. McCrea and Parimal G. Patil credit Dignaga with triggering an epistemic turn that reshaped non-Buddhist Sanskrit philosophy as well. The Hetucakradamaru, considered his first work on formal logic, stands as a bridge between earlier doctrine and the mature theory of vyapti, a concept related to what Western philosophy would call implication.