Introduction: Why the comparability problem is central in typology

Issues of comparability lie at the heart of linguistic typology.1 Consider proposals like (a)–(e), among thousands of interest to the field: (a) adjectives/noun phrases/complement clauses [etc.] are universal features of language. (b) languages with dominant VSO order are always prepositional. (c) case assignment is affected by definiteness more often in objects than in subjects. (d) languages never have more point-of-articulation contrasts for nasal stops than for oral stops. (e) senary (base-six) numeral systems are only found in Southern New Guinea. Each of these statements can only be falsified, or perhaps converted into a statistical rephrasing, if we know exactly what elements we are comparing – if we can sort out what Stassen (2010: 90) calls “the problem of cross-linguistic identification”. Do we mean the same thing by adjective, noun phrase, complement clause, VSO order, prepositional, definiteness, object, subject, oral stop, nasal stop, senary numeral system? None of these ontological questions are trivial, and much of the work done by typologists over the last century has gone into working out the best conceptual cuts, into operationalising definitions, and then, as they build their cross-linguistic databases, into the difficult job of deciding how to map descriptions of individual languages onto surveys of these categories.