(fl. c. 800) was an Indian philosopher known for his radical skepticism who most likely flourished between 800-840 probably in southern India. He was the author of one of the most extraordinary philosophical work in Indian history, the Tattvopaplavasiṃha (tattva-upa.plava-siṃha "The Lion that uproots all Philosophies"/"The Lion upsetting all Principles") in which he professed radical skepticism, which posits the impossibility of knowledge. In his work, he attempts to show the contradictions of various philosophical positions as well as the counter positions. He is loosely affiliated to the materialist Cārvāka/Lokāyata school of philosophy but his affiliation with charvaka is disputed among scholars. He has been differently classified as a sceptic, agnostic or materialist atheist. His main claim is that it is not possible to arrive at true knowledge with standard means recognized by the traditionally adopted model of cognitive procedures (pramāṇa) in Indian epistemology, because one should first properly define basic criteria of validity for valid cognitive procedures, which is not possible without a prior true knowledge of reality against which we could test the procedures for validity etc. As it is traditionally argued, our knowledge of reality and of objects depends on valid cognitive procedures. However, as Jayarāśi points out, all valid cognitive procedures are either fundamentally flawed and ultimately unreliable or they require further valid cognitive procedures, and these stand in the same need etc. Therefore, within the traditional epistemological model, we can neither formulate proper definitions of valid cognitive procedures nor define what reality is and what basic categories are. The text was discovered in a single manuscript in the 20th century. Its original 1940 edition attributed it to the materialist Charvaka school, but scholarly opinion on this point remains divided. Some consider Jyarāśi's philosophy as a heterodox philosophy in Indian materialist tradition or the Charvaka/Lokayata tradition as his radical skepticism makes him & his philosophy different from typical Charvaka/Lokayata materialist tradition. His work Tattvopaplavasiṃh remains the only authentic, albeit not 'orthodox' treatise of the charvaka/Lokayata tradition. The work is primarily epistemological in nature, reminiscent of the sceptical philosophy of David Hume. Tattvopaplavasimha The manuscript of Tattvopaplavasimha was discovered in 1926 and published in 1940 by Saṁghavī and Pārīkh. The book examines epistemology, where Jayarāśi considers the pramāna (sources of knowledge) accepted in establishing conclusions (perception, inference, and testimony), and proves that none of them are sufficient for establishing knowledge. Inference relies on inductive reasoning, which cannot be