Zen personal trouble or crisis. Though Zen-narrative states that it is a "special transmission outside scriptures" which "did not stand upon words", Zen does have a rich doctrinal background, which is firmly grounded in the Buddhist tradition. It was thoroughly influenced by the Chinese understanding of Yogacara and the Buddha-nature doctrine, Zen integrates both Yogacara and Madhyamaka and the influence of Madhyamaka can be discerned in the stress on non-conceptual insight and the paradoxical language of the koans. Most essential are "the most fundamental teaching that we are already originally enlightened", and the Bodhisattva ideal, which supplements insight with Karuṇā, compassion
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