Nyaya and Vaisheshika on knowledge, inference and the categories of nature; Samkhya and Yoga on mind and experience; Mimamsa on interpretation and language; Vedanta on metaphysics — six systems arguing against each other in a shared formal method.
Nyaya Sutra
Dates disputed and differing by school · disputed · disputed
Each sutra text has its own contested dating and later commentaries
Unknown or disputed.
Philosophy — The six darshanas and their debate tradition. Epistemology, metaphysics, logic, philosophy of language, and a formal tradition of public debate between rival schools.
Evidence: traditionally attributed · no modern scholarly reference recorded yet.