Two eight-century Jaina contemporaries, a Śvetāmbara philosopher Siddhasena Mahāmati and a Digambara Akalaṅka Bhaṭṭa revolutionised Jaina epistemology, by radically transforming basic epistemological concepts, which had been based on canonical tradition. The paper presents a brief historical outline of the developments of basic epistemological concepts in Jaina philolosophy such as the cognitive criterion and logical faculties as well as their fourteen typological models which serve as the backdrop of important innovations in epistemology introduced by Siddhasena, Pātrasvāmin and Akalaṅka. An important contribution (...) of these Jaina thinkers was to economize Indian logic and the rules of inference, first, by devising only one kind of logical reason called ‘inexplicability otherwise’, based on the single inseparable connection of the proving property with the inferable property, and, second, by limiting the necessary number of the members of the proof formula merely to two. These two innovations were related to the thinkers’ intention to devise a logic which would not primarily be based on empirical verification but its structural patterns would be valid irrespective of external observation. Further, the paper focuses on the nature of the epistemological shifts which Siddhasena and Akalaṅka introduced independently of each other and on the question how Siddhasena’s and Akalaṅka’s ideas were partly anchored in Buddhist concepts of the pramāṇa school of Diṅnāga and Dharmakīrti. With the Buddhist background, Siddhasena sought to define the criteria essential to distinguish true from false cognitions and to provide a novel classification of the pramāṇas. He can further be accredited with formulating the first Jaina descriptive definition of the cognitive criterion. The final section of the paper explains how Akalaṅka applies novel epistemological ideas, first, to construct realistic ontology and objectivity of both the external world and the cognising subject, and, secondly, to combat fundamental Buddhist concepts such as idealism and momentariness. (shrink)