Phonological constraints are not directly phonetic

The argument is made on the basis of constraints that have the same functional basis, but distinct formal properties: ONSET and *ONSET/X (§2). If phonetic factors are projected directly onto phonological constraints, then the shared functional basis of these constraints should entail that they cannot be formally distinct. Specifically, the direct-phonetics model predicts that ONSET is actually “*ONSET/Ø,” a constraint against null onsets that is the highest ranked member of the *ONSET/X family (§3). However, there is phonological evidence against equating ONSET with *ONSET/Ø. First, ONSET can be freely ranked with respect to *ONSET/X constraints, although the *ONSET/X constraints are themselves in a universally fixed relationship derived from the sonority scale (§4). Second, the behavior of glide-initial syllables in languages that avoid high-sonority onsets while also banning onsetless syllables shows that ONSET and *ONSET/X evaluate different phonological structures (§5). Each of these factors independently demonstrates that ONSET and *ONSET/X are formally distinct. Consequently, even phonetically grounded constraints like these do not encode phonetic information directly.