Insertion or deletion? CVCV/CCV alternations in Kru languages

Kru languages, spoken in Liberia and Côte d'Ivoire, show an alternation between CVCV and CCV in a subset of lexical items. The alternation is variable, where the same word can appear as either CVCV or CCV in a single environment, and lexically specific, where only a subset of morphemes alternate in this way. This paper describes the CVCV\slash CCV alternation in Kru, showing that whether this pattern is best categorized as an instance of vowel insertion or deletion differs by language. Two representative Kru case studies are presented in detail: The CVCV\slash CCV alternation in Dida is shown to be best analyzed as underlying /CCV/ with epenthesis or vowel intrusion, whereas the CVCV\slash CCV alternation in Guébie is shown to involve underlying /CVCV/ sequences with optional deletion of the initial vowel. Diagnostics are proposed for determining when a vowel/$\emptyset$ alternation is synchronically best analyzed as insertion or deletion. CVCV\slash CCV alternations found in nearby Kru, Mande, and Kwa languages are examined, leading to conclusions about the diachronic development of the CVCV\slash CCV alternation in West Africa.