Do morphophonological exchange rules exist? A reply to DiCanio et al. (2020)
DiCanio et al. (2020) (this volume) argue that San Martín Itunyoso Triqui has a morphophonological exchange (also called ‘polarity’), where morphemes are realized by switching feature values: e.g. the bare root [anĩɦ] ‘get dirty’ is realized as [anĩː] in the 1s, while the root [aniː] ‘stop’ is 1s [anĩɦ]. In this Reply, I seek to clarify how the descriptive use of ‘exchange’ relates to and differs from its meaning in phonological theories. I also show that the issue of whether exchanges exist is highly theory-dependent. For SPE, Lexical Phonology and Morphology, and single-level parallelist OT with opacity mechanisms, the IT forms do not provide evidence for exchange mechanisms. In contrast, a version of OT that lacks opacity mechanisms probably cannot generate the IT forms without an exchange mechanism. Issues facing the analyst, such as how to prove that exchanges exist, and which apparent exchanges one should expect to observe, are also discussed.