How did Dignaga’s Pramanasamuccaya help establish Buddhist logic?

Dignāga’s Pramāṇasamuccaya (“Compendium of the Means of True Knowledge”) is considered the foundational text that established Buddhist logic as a formal discipline.21

Dignāga revolutionized the field through two primary contributions:

• Definition of Perception: He redefined perception as knowledge entirely free from conceptual constructions, such as names or class concepts, identifying pure sensation as the only true form of perception.23
• Theory of Inference: He introduced a rigorous framework for logical reasoning, distinguishing between inference for oneself and inference for others. Central to this was his establishment of three criteria for a valid middle term (hetu): it must cover the minor premise (pakṣa), be present in similar instances (sapakṣa), and be absent in dissimilar instances (vipakṣa).23

Additionally, in his work Hetucakra (“The Wheel of ‘Reason’”), he developed a matrix of nine types of middle terms to categorize valid, contradictory, and uncertain conclusions. These innovations provided the structural basis for Buddhist epistemology, which was later expanded upon by Dharmakīrti.23