Berko’s (1958) wug-test is a standard part of the phonologist’s  toolkit. If you’re not sure if a pattern is productive, why not ask whether speakers extend it to nonce words? It makes sense; it has good face validity. However, I increasingly see linguists who think that the results of wug-tests actually trumps contradictory evidence coming from traditional phonological analysis applied to real words. I respectfully disagree. 

Consider for example a proposal by Sanders (2003, 2006). He demonstrates that an alternation in Polish (somewhat imprecisely called o-raising) is not applied to nonce words. From this he takes o-raising to be handled via stem suppletion. He asks, and answers, the very question you may have on your mind. (Note that his H here is the OT constraint hierarchy; you may want to read it as grammar.)

Is phonology obsolete?! No! We still need a phonological H to explain how nonce forms conform to phonotactics. We still need a phonological H to explain sound change. And we may still need H to do more with morphology than simply allow extant (memorized) morphemes to trump nonce forms. (Sanders 2006:10)¹

I read a sort of nihilism into this quotation. However, I submit that the fact that 50 million people just speak Polish—and “raise” and “lower” their ó‘s with a high degree of consistency across contexts, lexemes, and so on—is a more entrenched fact than the results of a small nonce word elicitation task. I am not saying that Sander’s results are wrong, or even misleading, just that his theory has escalated the importance of these results to the point where it has almost nothing to say about the very interesting fact that the genitive singular of lód [lut] ‘ice’ is lodu [lɔdu] and not *[ludu], and that tens of millions of people agree.

Endnotes

1. Sanders’ 2006 manuscript is a handout but apparently it’s a summary of his 2003 dissertation (Sanders 2003), stripped of some phonetic-interface details not germane to the question at hand. I just mention so that it doesn’t look like I’m picking on a rando. Those familiar with my work will probably guess that I disagree with just about everything in this quotation, but kudos to Sanders for saying something interesting enought to disagree with.

References

Berko, J. 1958. The child’s learning of English morphology. Word 14: 150-177.
Sanders, N. 2003. Opacity and sound change in the Polish lexicon. Doctoral dissertation, University of California, Santa Cruz.
Sanders, N. 2006. Strong lexicon optimization. Ms., Williams College and University of Massachusetts, Amherst.

I have previously discussed the notion of pure allophony, contrasting it with the facts of alternations. What follows is a lightly edited section from my recent NAPhC 12 talk, which in part hinges on this notion.

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While Halle (1959) famously dispenses with the structuralist distinction between phonemics and morphophonemics, some later generativists reject pure allophony outright. Let the phonemic inventory of some grammar G be P and the set of surface phones generated by G from P be S. If some phoneme p ∈ P always corresponds—in some to be made precise—to some phone s ∈ S and if s ∉ P then s is a pure allophone of p. For example, if /s/ is a phoneme and [ʃ] is not, but all [ʃ]s correspond to /s/s, then [ʃ] is a pure allophone of [s]. According to some descriptions, this is the case for Korean, as [ʃ] is a (pure) allophone of /s/ when followed by [i].

One might argue that alternations are more entrenched facts than pure allophony, simply because it is always possible to construct a grammar free of pure allophony. For instance, if one wants to do away with pure allophony one can derive the Korean word [ʃI] ‘poem’ from /ʃi/ rather than from /si/. One early attempt to rule out pure allophony—and thus to motivate the choice of /ʃi/ over /si/ for the this problem—is the alternation condition (Kiparsky 1968). As Kenstowicz & Kisseberth (1979:215) state it, this condition holds that “the UR of a morpheme may not contain a phoneme /x/ that is always realized phonetically as identical to the realization of some other phoneme /y/.” [Note here that /x, y/ are to be interpreted as variables rather than as the voiceless velar fricative or the front high round vowel.–KBG] Another recent version of this idea—often attributed to Dell (1973) or Stampe (1973)—is the notion of lexicon optimization (Prince & Smolensky 1993:192).

A correspondent to this list wonders why, in a grammar G such that G(a) = G(b) for potential input elements /a, b/, a nonalternating observed element [a] is not (sometimes, always, freely) lexically /b/. The correct answer is surely “why bother?”—i.e. to set up /b/ for [a] when /a/ will do […] The basic idea reappears as “lexicon optimization” in recent discussions. (Alan Prince, electronic discussion; cited in Hale & Reiss 2008:246)

Should grammars with pure allophony be permitted? The question is not, as is sometimes supposed, a purely philosophical one (see Hale & Reiss 2008:16-22): both linguists and infants acquiring language require a satisfactory answer. In my opinion, the burden of proof lies with those who would deny pure allophony. They must explain how the language acquisition device (LAD) either directly induces grammars that satisfy the alternation condition, or optimizes all pure allophony out of them after the fact. “Why bother” could go either way: why posit either complication to the LAD when pure allophony will do? The linguist faces a similar problem to the infant. To wit, I began this project assuming Latin glide formation was purely allophonic, and only later uncovered—subtle and rare—evidence for vowel-glide alternations. Thus in this study, I make no apology for—and draw no further attention to—the fact that some data are purely allophonic. This important question will have to be settled by other means.

References

Dell, F. 1973. Les règles et les sons. Hermann.
Hale, M, and Reiss, R.. 2008. The Phonological Enterprise. Oxford University Press.
Halle, M. 1959. The Sound Pattern of Russian. Mouton.
Kenstowicz, M. and Kisseberth, C. 1979. Generative Phonology: Description and Theory. Academic Press.
Kiparsky. P. 1968. How Abstract is Phonology? Indiana University Linguistics Club.
Prince, A. and Smolensky, P. 1993. Optimality Theory: Constraint interaction in generative grammar. Technical Report TR-2, Rutgers University Center For Cognitive Science and Technical Report CU-CS-533-91, University of Colorado, Boulder Department of Computer Science.
Stampe, D. 1973. A Dissertation on Natural Phonology. Garland.

[Leaving this as a note to myself to circle back.]

I’m just going to say it: some “rules” are probably two or three rules, because the idea that rules are defined by natural classes (and thus free of disjunctions) is more entrenched than our intuitions about whether or not a process in some language is really one rule or not, and we should be Gallilean about this. Here are some phonological “rules” that are probably two or three rules different rules.

• Indo-Iranian, Balto-Slavic families, and Albanian “ruki” (environment: preceding {w, j, k, r}): it is not clear to me if any of the languages (the) actually need this as a synchronic rule at all.
• Breton voiced stop lenition (change: /b/ to [v], /d/ to [z], /g/ to [x]): the devoicing of /g/ must be a separate rule. Hat tip: Richard Sproat. I believe there’s a parallel set of processes in German.
• Lamba patalatalization (change: /k/ to [tʃ], /s/ to [ʃ]): two rules, possibly with a Duke-of-York thing. Hat tip: Charles Reiss.
• Mid-Atlantic (e.g., Philadelphia) English ae-tensing (environment: following tautosyllabic, same-stem {m, n, f, θ, s, ʃ]): let’s assume this is allophony; then the anterior nasal and voiceless fricative cases should be separate rules. It is possible the incipient restructuring of this as having a simple [+nasal] context provides evidence for the multi-rule analysis.
• Latin glide formation (environment: complex). Front and back glides are formed from high short monophthongs in different but partially overlapping contexts.

[This is a quick writing exercise for in-progress work with Charles Reiss. Sorry if it doesn’t make sense out of context.]

An anonymous reviewer asks:

I wonder how the author(s) would reconcile this learning model with the evidence that both children and adults seem to aggressively generalize phonotactic restrictions from limited data (e.g. just [p]) to larger, unobserved natural classes (e.g. [p f b v]). See e.g. the discussion in Linzen & Gallagher (2017). If those results are credible, they seem much more consistent with learning minimal feature specifications for natural classes than learning maximal ones.

First, note that Linzen & Gallagher’s study is a study of phonotactic learning, whereas our proposal concerns induction of phonological rules. We have been, independently but complementarily, quite critical of the naïve assumptions inherent in prior work on this topic (e.g., Gorman 2013, ch. 2; Reiss 2017, §6); we have both argued that knowledge of phonotactic generalizations may require much less grammatical knowledge than is generally believed.

Secondly, we note that Linzen & Gallagher’s subjects are (presumably; they were recruited on Mechanical Turk and were paid $0.65 USD for their efforts) adults briefly exposed to an artificial language. While we recognize that adult “artificial language learning” studies are common practice in psycholinguistics, it is not clear what such studies contribute to our understanding of phonotactic acqusition (whatever the phonotactic acquirenda turn out to be) by children robustly exposed to realistic languages in situ.

Third, the reviewer is incorrect; the result reported by Linzen & Gallagher (henceforth L&G) is not consistent with minimal generalization. Let us grant—for sake of argument—that our proposal about rule induction in children is relevant to their work on rapid phonotactic learning in adults. One hypothesis they entertain is that their participants will construct “minimal classes”:

For example, when acquiring the phonotactics of English, learners may first learn that both [b] and [g] are valid onsets for English syllables before they can generalize to other voiced stops (e.g., [d]). This generalization will be restricted to the minimal class that contained the attested onsets (i.e., voiced stops), at least until a voiceless stop onset is encountered.

If by a “minimal class” L&G are referring to a natural class which is consistent with the data and has an extension with the fewest members, then presumably they would endorse our proposal of feature maximization, since the class that satisfies this definition is the most fully specified empirically adequate class. However, it is an open question whether or not such a class would actually contain [d]. For instance, if one assumes that major place features are bivalent, then the intersection of the features associated with [b, g] will contain the specification [−coronal], which rules out [d].

Interestingly, the matter is similarly unclear if we interpret “minimal class” intensionally, in terms of the number of features, rather than in terms of the number of phonemes the class picks out. The (featurewise-)minimal specification for a single phone (as in the reviewer’s example) is the empty set, which would (it is generally assumed) pick out any segment. Then, we would expect that any generalization which held of [p], as in the reviewer’s example, to generalize not just to other labial obstruents (as the reviewer suggests), but to any segment at all. Minimal feature specification cannot yield a generalization from [p] to any proper subset of segments, contra the anonymous reviewer and L&G. An adequate minimal specification which picks out [p] will pick out just [p].; L&G suggest that maximum entropy models of phonotactic knowledge may have this property, but do not provide a demonstration of this for any particular implementation of these models.

We thank the anonymous reviewer for drawing our attention to this study and the opportunity their comment has given us to clarify the scope of our proposal and to draw attention to a defect in L&G’s argumentation.

References

Gorman, K. 2013. Generative phonotactics. Doctoral dissertation, University of Pennsylvania.
Linzen, T., and Gallagher, G. 2017. Rapid generalization in phonotactic learning. Laboratory Phonology: Journal of the Association for Laboratory Phonology 8(1): 1-32.
Reiss, C. 2017. Substance free phonology. In S.J. Hannahs and A. Bosch (ed.), The Routledge Handbook of Phonological Theory, pages 425-452. Routledge.