Zen expected to become familiar with the classics of the Zen canon". A review of the early historical documents and literature of early Zen masters clearly reveals that they were well versed in numerous Mahāyāna Buddhist sūtras, including Madhyamaka. Especially the Lotus Sutra played a large role in the development of East Asian Buddhism, including Zen. Nevertheless, Zen is often pictured as anti-intellectual. This picture of Zen emerged during the Song Dynasty (960–1297), when Chán became the dominant form of Buddhism in China, and gained great popularity among the educated and literary classes of Chinese society. The use of koans, which
Defeasible reasoning in part because proponents of informal logic became the keepers of argument and rhetoric while insisting that formalism was anathema to argument. About this time, researchers in artificial intelligence became interested in non-monotonic reasoning and its semantics. With philosophers such as Pollock and Donald Nute (e.g., defeasible logic), dozens of computer scientists and logicians produced complex systems of defeasible reasoning between 1980 and 2000. No single system of defeasible reasoning would emerge in the same way that Quine's system of logic became a de facto standard. Nevertheless, the 100-year headstart on non-demonstrative logical calculi, due to George Boole, Charles Sanders