What should phonology explain ?

A standard observation about the phonological patterns found in the world's languages, and a standard explanation of this observation: (1) Phonetically motivated (" natural ") processes are common in the phonologies of the world's languages, while phonetically unmotivated (" unnatural ") ones are uncommon. (2) The causes of phonological patterns are represented in the mental grammar. A phonological process is " natural " to the extent that it is easily expressed by the tools of the theory. This is markedness in a general sense, though the specifics vary: b. It also broadly characterizes mainstream generative approaches (including Chomsky and Halle 1968, Kiparsky 1973, and the subsequent tradition). c. It is a basic assumption of much recent work in Optimality Theory (Prince and Smolensky 1993) that incorporates into the phonology phonetic constraints on outputs, ranging from perceptibility of acoustic cues in particular contexts to the general principle of least effort (cf. I argue that while (1) is certainly correct, the markedness explanation in (2) makes false predictions regarding the historical development of phonological systems (cf. appropriate explanation for the frequency of phonetically motivated sound patterns is simply that they are more likely to arise historically than " unnatural " ones. (4) The phonetic causes of phonological patterns occur in the transmission of language from speaker to learner. They are not (redundantly) represented in the grammar. This view leaves open the possibility that unnatural processes will arise for various reasons, and predicts that learners construct grammars that do not distinguish between natural and unnatural patterns. While phonetically driven approaches correctly identify the factors that lead to common alternations, it is problematic to incorporate these factors into the grammar itself. From the learner's (and the grammar's) point of view, the original cause of an alternation is irrelevant: the learner's only goal is to reproduce the language she hears around her. A phonetically natural, and therefore widely attested, pattern is lowering of vowels next to a uvular consonant. This lowering has clear motivation in the similar articulations of the low uvular consonants and the lowered vowels (see also Maddieson and Ladefoged 1996:36 for acoustic effects). I illustrate with three languages, giving a range of stages in phonologization.