French liaison is allomorphy, not allophony: evidence from lexical statistics

The exact nature of French liaison as a phonological or morphological alternation is still debated. Under the phonological analysis, liaison is allophony: liaison consonants are special phonemes that alternate between a consonant allophone and zero (e.g., [t] ∼ ∅), the zero allophone being derived from the consonant phoneme through deletion (/t/ → ∅). Under the morphological analysis, liaison is allomorphy: liaison words have two underlyingly listed allomorphs, a consonant-final allomorph and a shorter allomorph that lacks this consonant (e.g., grand ‘great’ /gʁɑ̃t, gʁɑ̃/). This paper uses evidence from lexical statistics to arbitrate between these two analyses. The form without liaison consonant (and with deletion, under the phonological analysis) has been found in previous research to become less likely with increasing lexical frequency. The paper shows that this is problematic for the phonological analysis of French liaison, as deletion typically applies more frequently in high-frequency words across languages. The paper further shows, using evidence from a large lexical database, that words involved in liaison alternations generally have lower type frequency but higher token frequency than non-liaison words when phonotactic and morphological effects on lexical frequency are controlled for. This result is in line with the predictions of the morphological analysis, as allomorphy typically involves a relatively small number of words that occur frequently. Due to its empirical nature, this argument constitutes to date one of the strongest arguments in favor of the morphological analysis.