Recently I have attempted to review and synthesize different theories of what we might call lexical (or morpholexical or morpheme-specific) exceptionality. I am deliberately ignoring accounts that take this to be a property of segments via underspecification (or in a few cases, pre-specification, usually of prosodic-metrical elements like timing slots or moras), since I have my own take on that sort of thing under review now. Some takeaways from my reading thus far:

• This is an understudied and undertheorized topic.
• At the same time, it seems at least possible that some of these theories are basically equivalent.
• Exceptionality and its theories play only a minor role in adjudicating between competing theories of phonological or morphological representation, despite their obvious relevance.
• Also despite their obvious relevance, theories of exceptionality make little contact with theories of productivity and defectivity.

Since most of the readings are quite old, I will include PDF links when I have a digital copy available.

Today, I’m going to start off with Chomsky & Halle’s (1968) Sound Pattern of English (SPE), which has two passages dealing with exceptionality: §4.2.2 and §8.7. While I attempt to summarize these two passages as if they are one, they are not fully consistent with one another and I suspect they may have been written at different times or by different authors. Furthermore, it seemed natural for me to address, in this same post, some minor revisions proposed by Lakoff (1970: ch. 2). Lakoff’s book is largely about syntactic exceptionality, but the second chapter, in just six pages, provides important revisions to the SPE system. I myself have also taken some liberties filling in missing details.

Chomsky & Halle give a few examples of what they have in mind when they mention exceptionality. There is in English a rule which laxes vowels before consonant clusters, as in convene/conven+tion or (more fancifully) wide/wid+th. However, this generally does not occur when the consonant cluster is split by a “#” boundary, as in restrain#t.¹ The second, and more famous, example involves the trisyllabic shortening of the sort triggered by the -ity suffix. Here laxing also occurs (e.g., serene–seren+ity, obscene–obscen+ity) though not in the backformation obese-obesity.² As Lakoff (loc. cit.:13) writes of this example, “[n]o other fact about obese is correlated to the fact that it does not undergo this rule. It is simply an isolated fact.” Note that both of these examples involve underapplication, and the latter passage gives more obesity-like examples from Lightner’s phonology of Russian, where one rule applies only to “Russian” roots and another only to “Church Slavonic” roots.

SPE supposes that by default, that there is a feature associated with each rule. So, for instance, if there is a rule R there exists a feature [R] as well. A later passage likens these to features for syntactic category (e.g., [+Noun]), intrinsic morpho-semantic properties like animacy, declension or conjugation class features, and the lexical strata features introduced by Lees or Lightner in their grammars of Turkish and Russian. SPE imagine that URs may bear values for [R]. The conventions are then:

(1) Convention 1: If a UR is not specified [-R], introduce [+R] via redundancy rule.
(2) Convention 2: If a UR is [αR], propagate feature specification [αR] to each of its segments via redundancy rule.
(3) Convention 3: A rule R does not apply to segments which are [-R].

Returning to our two examples above, SPE proposes that obese is underlylingly [−Trisyllabic Shortening], which accounts for the lack of shortening in obesity. They also propose rules which insert these minus-rule features in the course of the derivation; for instance, it seems they imagine that the absence of laxing in restraint is the result of a rule like V → {−Laxing} / _ C#C, with a phonetic-morphological context.

Subsequent work in the theory of exceptionality has mostly considered cases like obesity, the rule features are present underlyingly but with one exception, discussed below, the restraint-type analysis, in which rule features are introduced during the derivation, do not seem to have been further studied. It seems to me that the possibility of introducing minus-rule features to a certain phonetic context could be used to derive a rule that applies to unnatural classes. For example, imagine an English rule (call it Tensing) which tenses a vowel in the context of anterior nasals {m, n} and the voiceless fricatives {f, θ, s, ʃ} but not voiced fricatives like {v, ð}.³ Under any conventional feature system, there is no natural class which includes {m, n, f, θ, s, ʃ} but not also {ŋ, v}, etc. However, one could derive the desired disjunctive effect by introducing a -Tensing specification when the vowel is followed by a dorsal, or by a voiced fricative. This might look something like this:

(4) No Tensing 1: [+Vocalic] → {−Tensing} / _ [+Dorsal]
(5) No Tensing 2: [+Vocalic] → {−Tensing} / _ [-Voice, +Obstruent, +Continuant]

This could continue for a while. For instance, I implied that Tensing does not apply before a stop so we could insert a -Tensing  specification when the following segment is [+Obstruent, -Continuant], or we could do something similar with a following oral sonorant, and so on. Then, the actual Tensing rule would need little (or even no) phonetic conditioning.

To put it in other words, these rules allow the rule to apply to a set of segments which cannot be formed conjunctively from features, but can be formed via set difference.⁴ Is this undesirable? Is it logically distinct from the desirable “occluding” effect of bleeding in regular plural and past tense allomorphy in English (see Volonec & Reiss 2020:28f.)? I don’t know. The latter SPE passage seems to suggest this is undesirable: “…we have not found any convincing example to demonstrate the need for such rules [like my (4-5)–KBG]. Therefore we propose, tentatively, that rules such as [(4-5)], with the great increase in descriptive power that they provide, not be permitted in the phonology.” (loc cit.:375). They propose instead that only readjustment rules should be permitted to introduce rule features; otherwise rule feature specifications must be underlyingly present or introduced via redundancy rule.

As far as I can see, SPE does not give any detailed examples in which rule feature specifications are introduced via rule. Lakoff however does argue for this device. There are rules which seem to apply to only a subset of possible contexts; one example given are umlaut-type plurals in English like foot–feet or goose–geese. Later in the book (loc. cit./, 126, fn. 59) these are referred to these as minor rules. Let us call the English umlauting rule simply Umlaut. Lakoff notes that if one simply applies the above conventions naïvely, it will be necessary to mark a huge number of nouns—at the very least, all nouns which have a [+Back] monophthong in the final syllable and which form a non-umlauting plural—as [-Umlaut]. This, as Lakoff notes, would wreck havoc on the feature counting evaluation metric (see §8.1), and would treat what we intuitively recognize as exceptionality (forming an umlauting plural in English) as “more valued” than non-exceptionality. Even if one does not necessarily subscribe to the SPE evaluation metric, one may still feel that this has failed to truly encode the productivity distinction between minor rules and major rules that have exceptions. To address this, Lakoff proposes there is another rule which introduces [–Umlaut], and that this rule (call it No Umlaut) applies immediately before Umlaut. Morphemes which actually undergo Umlaut are underlying -No Umlaut. Thus the UR of an noun with an umlauting plural, like foot, will be specified [–No Umlaut], and this will not undergo a rule like the following:

(6) No Umlaut: [ ]  → [–Umlaut]

However, a noun with a regular plural, like juice, will undergo this rule and thus the umlauting rule U will not apply to it because it was marked [-U] by (6).

One critique is in order here. It is not clear to me why SPE introduces (what I have called) Convention 2; Lakoff simply ignores it and proposes an alternative version of Convention 3 where target morphemes must be [+R] to undergo rule R. Of his proposal, he writes: “This system makes the claim that exceptions to phonological rules are morphemic in nature, rather than segmental.” (loc. cit., 18) This claim, while not necessarily its 1970-era implementation, is very much in vogue today. There are some reasons to think that Convention 2 introduces unnecessary complexities. One example (SPE:374) makes it clear that for Chomsky & Halle, Convention 3 requires that that for rule R the target be [+R], but later on, they briefly consider what if anything happens if any segments in the environment (i.e., structural change) are [-R].⁵ They claim (loc. cit., 375) there are problems with allowing [-R] specifications in the environment to block application of R, but give no examples. To me, this seems like an issue created by Convention 2, when one could simply reject it and keep the rule features at the morpheme level.

[This post, then, is the first in a series on theories of lexical exceptionality.]

Endnotes

1. The modern linguist would probably not regard words like restraint as  subject to this rule at all. Rather, they would probably assign #t to the “word” stratum (equivalent to the earlier “Level 2”) and place the shortening rule in the “stem” stratum (roughly equivalent to “Level 1”). Arguably, C&H have stated this rule more broadly than strictly necessary to make the point.
2. It is said that the exceptionality of this pair reflects its etymology: obese was backformed from the earlier obesity. I don’t really see how this explains anything synchronically, though.
3. This is roughly the context in which Philadelphia short-a is tense, though the following consonant must be tautosyllabic and tautomorphemic with the vowel. Philadelphia short-a is, however, not a great example since it’s not at all clear to me that short-a tensing is a synchronic process.
4. Formally, the set in question is something like [−Dorsal] ∖ [+Voice, +Consonantal, +Continuant, −Nasal].
5. This issue is taken up in more detail by Kisseberth (1970); I’ll review his proposal in a subsequent post.

References

Chomsky, N. and Halle, M. 1968. Sound Pattern of English. Harper & Row.
Kisseberth, C. W. 1970. The treatment of exceptions. Papers in Linguistics 2: 44-58.
Lakoff, G. 1970. Irregularity in syntax. Holt, Rinehart and Winston.