 Canons A73–74 give a precise explication of disputation in its most concrete sense. It is contending over which of two complementary terms, such as ‘ox’ and ‘non-ox’, “fits” (dàng 當) a thing (shí) (A74). Such pairs of terms divide everything in the world into two mutually exclusive categories: any one thing is either ox or non-ox. In disputation, one side calls a thing “ox,” the other “non-ox”; the side whose claim fits the thing wins. The text cites a version of the law of excluded middle (A73) to show that at least one of the pair of terms must fit and a version of the law of non-contradiction (A74) to show that at least one must fail to  fit.[25]  The speech act of calling the thing “ox” or “non-ox” has the pragmatic significance of an assertion, and so disputation can be understood by our lights as a debate over which of two contradictory assertions is true. But the Mohists do not view it this way. They see it as contending over whether the shí (stuff, thing) at hand is of the kind ox or not. Equivalently, they see it as debating whether, with respect to the term ‘ox’, the thing at hand is “this” (shì) or “not-this” (fēi)—whether the term “fits” it or not. 