Japanese Zen expressions of this selfless existence. Zen emphasizes zazen, meditation c.q. dhyana in astting position. In Soto, the emphasis is on shikantaza, 'just sitting', while Rinzai also uses koans to train the mind. In alternation with zazen, there is walking meditation, "kinhin", in which one walks with full attention. To facilitate insight, a Zen teacher can assign a kōan. This is a short anecdote, which seems irrational, but contains subtle references to the Buddhist teachings. An example of a kōan is Joshu's 'Mu': "A monk asked: "Does a dog have buddha-nature?" Joshu responded: "Mu!"" Zen-meditation aims at "non-thinking," in Japanese "fu
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