Taxa are mutually exclusive. Terminal contrast occurs between those named groupoings which include no additional named groupings. There is little systematic relation between terminal folk taxa and scientific taxa. Better move is to base comparison on notion of rank, but this is much more difficult to do. Ranking is a cognitive mapping that places living-kind categories in a structure of absolute levels, which may be evolutionarily designed to correspond to fundamentally different levesl of reality.
Different ranks involve paying attention to different kinds of information to make a classification.
By far the majority of taxa in any folk-biological classification belong to the level of the folk species. It is this level that people in most societies privilege when they see and talk about biological discontinuities. Cross-cultural evidence suggests that the most basic level in Rosch's sense is a variable phenomenon that shifts as a function of general cutlural significance and individual familiarity and expertise. Atran describes a degeneration of folk biology in urban societies. This spontaneous arrangement of living things into taxonomies of essential kinds thus constitutes a prior set of constraints on any and all possible theories about the causal relations between living kinds.