Dealing with Exceptions

It should be noted that neither the CN84 nor the Chen76 RC is entirely bind­

p.349 - reversal of usual order of LABIAL DISSIMILATION and LENGTH) . One reason for the occasional conflicts between the philological and linguistic approaches in reconstructing protoforms is the "dominance of a long and ven­ erable philological tradition within the Chinese culture" (Newman 1996, p.92) that was discussed in Section 4.2. 1 . When linguistic reconstruction of a form using the comparative method conflicts with Chinese philological evidence, the latter form is usually adopted and an exception introduced into the diachronic derivation process.

Such exceptions also bear significance in the results obtained. A large num­ ber of unpredictable exceptions to the linguistic hypothesis will contribute to a greater complexity in the diachronic phonology. If we assume that these ex­ ceptions are a result of residual forms being left behind in a language, then one could say that the complexity of a language increases with time due to the presence of such residual forms and exceptions (Crowley 1987, p. 150-153) . The PFSA derived for the more distant language will have a greater MML than the other. If on the other hand, one subscribes to the wave theory of linguistic change and assumes that exceptions are caused by a change that has swept over part of a geographic region, and is yet to affect phonemes completely in other parts, then a greater MML would indicate quite the opposite since a completed linguistic change is considered to achieve uniformity of application.

The problem surfaces for any work that needs to utilise a reconstruction comprehensively because the exceptions have not been accounted for by any of the popular reconstructions, including the two that this dissertation is con­ cerned with - Chen76 and CN84. Whatever the reasons for these exceptions, and whatever their significance may be, it remains that they pose some prob­ lems to this project. They must be dealt with and incorporated somehow into the framework of deriving distance measures. Besides the obvious problem of deciding how to deal with them, they constitute a reason for being unable to automate the process of generating derivations, since the entire output of an automatic derivation process will have to be checked for exceptions anyway. The following subsections discuss the most common types of exceptions and

the decisions made towards addressing them.

4.9.1 Exceptions to the RC

Consistentency with the RC proposed in Chen76 and CN84 has been main­ tained as far as possible. For the most part, violations to them are viewed as serious exceptions. Thus if Rule A is ordered before Rule B in the RC, but is required to apply after Rule B in a specific instance under consideration, it is made an exceptional application of Rule A, denoted by "[A] " . Such excep­ tional rules are considered distinct from their normal forms. The sequence of rules deriving Beijing tou from SMC *to ( "all" ) , for example, is given as "t l­ split:raise-u:diphthong-u:chamel:" . However, "diphthong-u" is ordered before "raise-u" in the RC. It is thus made an exceptional application and the rule sequence is given instead as "t l-split:raise-u: [diphthong-u] :chamel:" .

4.9.2 Undocumented Changes

There are also exceptional phonological changes not accounted for by CN84 or Chen76. In these cases, a new rule is formed in consultation with John Newman representing the change that took place, and it is denoted in square brackets to show its exceptional status. Related exeptions are grouped together as a single exceptional rule. For example, Tone-4 in SMC only changes to Tone- la or Tone-2 in Beijing when the form has a voiceless initial. However, for the SMC form *niat ( "pinch with fingers" ) in Tone-4, the corresponding Beijing form is nie in Tone- la. Since the n-initial is voiced, the t4-tripart rule is considered to apply exceptionally. The complete rule sequence is thus denoted by "raise-i:apocope:chamel: [t4] :" where the "[t4]" exceptional rule covers cases when Tone-4 in SMC unexpectedly changed into Tone-la or Tone-2 in Beijing in the absence of a voiceless initial.

4.9.3 Unapplied Rules

It also needs to be mentioned that there are a few cases where an environment for the application of a rule existed, but the rule itself did not apply although

it was required to by the CN84 or Chen76 hypothesis. This would constitute an exception again. The details of how to handle this situation more accurately are left as a topic for future work, but we try to account for it here by applying a special rule [!A] where the ' ! ' is meant to indicate that the rule A didn't apply when it ought to have. As an example, we may consider the derivation of Modern Cantonese hap (Tone 4a) from SMC *0ap(Tone 4) ( "exactly" ) . The sequence of rules deriving the MC form is "t4-split:spirant:x-weak:" . However, since the environment is appropriate (voiceless initial) for the application of a further rule, AC-split, which should apply after t4-split had applied, the non-application of this additonal rule is specified as an exception. Thus, "t4- split :spirant:x-weak: [!AC-split] :" is the actual rule sequence used.

In general, the following conventions in representing and treating exceptions have been followed as far as possible: Exceptional rules are always denoted in square brackets. They are considered excluded from the RC and thus are consistently ordered at the end of the rest of the derivation process wherever possible.

The most frequent exception thus encountered in the data was the unex­ pected occurrence of Tone A in a Modern Cantonese form, where the corre­ sponding SMC form had a voiced initial. CN84's TONE-SPLIT rule (CN84- I, p. l65) predicts Tone B in such Cantonese forms. This exception occurs in 90 of the 2714 forms, approximately 3.28% of the total sample. It is noteworthy that it is sometimes possible to avoid exceptions such as this by violating the RC - in this case, by ordering the DEVOICE rule before the TONE-SPLIT rule, but from the preceding discussion, even this would constitute an exception. So either way there is a penalty to pay for describing this change.

In the few cases that exceptions have a feeding or bleeding relationship to other rules, they are ordered in-line with the other P-rules. In some cases, a derivation may be composed of two or more rule sequences, within each of which rules may be ordered, but the sequences themselves neither bleed nor feed one another within the context of the word being derived. Here again, an attempt to be consistent is made by ordering the earlier rules before later ones.