The differential substitution of English /θ ð/ in French

Summary One of the most interesting problems in second-language (L2) phonology is how to account for differential substitution. This is the phenomenon by which speakers who lack a certain segment (sequence) in their first language (L1) may adopt alternative language-specific replacement strategies in the L2 they are attempting to acquire. It has recently been claimed by Weinberger (1997) that the reason why, for example, Japanese learners of English systematically replace English /θ ð/ by /s z/ while their Russian counterparts always substitute /t d/ is that fricatives are unspecified for the feature [continuant] in Japanese while in Russian, the stops constitute the default obstruents. What is argued here is that this analysis in terms of Underspecification Theory cannot possibly work in the case of European and Canadian French which evince an equally systematic differential substitution of /θ ð/ to /s z/ and /t d/ respectively even though they have an identical system of underlying obstuents. It is also suggested that a perception-based approach to the thorny problem of differential substitution would appear to be a much more promising avenue of research.