ABSTRACT
It is common for writers to relate legal concepts to each other in terms of such metaphors as maps and organisational or taxonomic schemes. Distinctions are drawn among contract, tort, and unjust enrichment, and between obligations and property, and, at a higher level of generality, between private rights and public policy. These distinctions are then commonly depicted as distinct areas on a map, or as separate classes, orders, genera, and species in a taxonomic scheme. Metaphors may illuminate a complex subject, but any metaphor, if pressed too far, is apt to distort. The ideas of mapping and taxonomy in law owe their attraction partly to their indeterminacy and variability. Mapping, as applied to law, is not a single metaphor, but multiple metaphors: the idea of a political map is not the same metaphor as the idea of a map of physical geography, and the idea of an urban map differs from the idea of a global map of seas and continents. Any set of ideas may claim its map, but different writers have used the word in different ways. Blackstone spoke of a map,1 and his map (rights of persons, rights of things, private wrongs, public wrongs) was useful for his purpose but plainly did not seek to set out mutually exclusive categories. Many private law obligations might fall simultaneously into all of his first three books. Modern writers, by contrast, have often envisaged a map that separates obligations rather as a map of physical geography separates places (Ottawa is in Canada, and therefore not in Europe) or as a taxonomical scheme separates biological specimens (an animal is either an insect or a mammal, but cannot be both).
