In linguistic typology, the case hierarchy is a particular order of cases where languages that lack a particular case are unlikely to have any of the cases listed after it in the hierarchy; languages that do have a particular case, however, will usually have at least one case from each position on its left. It was developed by the Australian linguist Barry Blake. The hierarchy is as follows:
This is only a general tendency, however. Many forms of Central German such as Colognian or Luxembourgish have a dative case but lack a genitive. In Irish nouns, the nominative and accusative have fallen together, while the dative and locative cases have remained separate in some paradigms; Irish also has a genitive and vocative case. In Punjabi, the accusative, genitive, and dative have merged to an oblique case, but the language still retains vocative, locative, and ablative cases. Old English had an instrumental case, but not a locative or prepositional.
Blake argues that it is "doubtful that the hierarchy can be extended much further", but does suggest that the most common cases not listed in the hierarchy are the comitative, purposive, allative, perlative and comparative.