Substance-free phonology (SFP) is based on the hypothesis that phonological computation makes no reference to phonetic substance, and that phonological features are treated as arbitrary symbols for the purposes of computation. However, phonologists within the SFP tradition disagree about whether the content of phonological features is innate or learned (“emergent”), and if learned, whether the acquisition process is based on phonological patterning alone or refers to phonetic substance. In the present article we identify predictive differences between these accounts. We conclude that there is an innate basis to phonological features, but that featural content is not innate. We suggest that a hybrid phonetic-phonological approach to feature content acquisition may ultimately be the most successful.
