 Such judgments will typically be based on comparison with selected features of a limited set of exemplars. We will usually proceed by identifying a few distinguishing features of a handful of representatives of the kind, a process the Mohists call “settling the kind” (B1). Yet things of the same kind may be dissimilar in some respects, while things of different kinds may nevertheless share some similarities. So problems can arise in identifying distinguishing features and differentiating kinds. The Mohists call this the “difficulty of extending kinds” (B2). The canon that presents the problem is corrupt and obscure, but we can make an educated conjecture as to its gist. It identifies two sources of difficulty: first, some features, but not all, are shared by every member of a kind; second, because kinds may be larger or smaller in scope, two things may be similar in both falling under one kind without being similar in falling under another. All quadrupeds are alike in having four feet, but not all are alike in being oxen, horses, or deer. Birds and all other animals are alike in being living creatures, but not all animals are birds. One cannot invariably generalize from features of an exemplar to claims about an entire kind, because—with the exception of special cases such as being four-footed—it is not obvious from the exemplar which features are shared by all members of the kind. Thus in disputation the process of identifying features of individual exemplars that are indeed representative of their kind will always be fallible. 