Genetic dysphasia and linguistic theory

J. Neurolinguisrics,

Vol. 10, No. 2/3, pp. 47-73, 1997 0 1997 Elsevier Science Ltd All rights reserved. Printed in Great Britain 0911+044/97 $17.00+0.00 PII:S0911-6044(97)00002-X

Pergamon

GENETIC DYSPHASIA

AND LINGUISTIC

FREDERICK University

THEORY

J. NEWMEYER

of Washington,

Seattle, U.S.A

Abstract-Linguists have good reason to pay close attention to studies of genetic dysphasia, as they promise to be of great relevance to controversies in the field. In particular, genetic dysphasia provides evidence that seems to point incontrovertibly to a genetic basis for grammar. It is, however, premature to advance claims as to how current approaches to grammar might capture the range of deficits that have been observed or how genetic dysphasia itself might decide in favor of one or another model of grammatical theory. Even so, genetic dysphasia does appear to have immediate import to three areas of interest to linguists: the cognitive systems involved in inflectional morphology, the phylogenesis of grammar, and the nature of adult-acquired second languages. 0 1997 Elsevier Science Ltd

1. INTRODUCTION The goal of this paper is to explore how genetic dysphasia (GD) might bear on controversies in the field of linguistics. Section 2 provides historical background. It reviews the trend over the past two centuries away from the ‘common sense’ view that the properties of language are a product of the social and communicative context of its use and toward one in which the central core of language is an autonomous structural system whose properties are rooted in the human genome. In Section 3, I review the two principal types of evidence in support of such a view: grammar-based and external. Neither has met with fully general acceptance, since the data lends itself to multiple interpretations. However, as is argued in Section 4, GD does provide evidence that seems to point incontrovertibly to a genetic basis for autonomous grammar. Section 5 takes on the question of how current approaches to grammar might capture the range of deficits observed in GD and concludes that it is premature to make pronouncements in this matter. Section 6 discusses the relevance of GD for three areas of interest to linguists: the cognitive systems involved in inflectional morphology, the phylogenesis of grammar, and the nature of adult-acquired second languages. Section 7 is a brief conclusion.

2. LINGUISTIC

THEORY

AND COMMON

SENSE

This section traces the development of, and opposition to, the hypothesis that there is a structural system at the heart of language, central features of which are innately determined. 2.1. The autonomy

and innateness

hypotheses

Linguistic theory, it might be said, is a field that offends common sense. That is, no other academic discipline comes to mind whose mainstream theoretical conceptions are so directly at odds with what educated opinion assumes that they should be. It is sometimes said that if you tell somebody that you work in linguistics, they will immediately ask you how many languages you speak. In my experience, that is not the most common reaction. Instead, one tends to be assailed with platitudes about the importance of communication and how all of the problems of 47

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the modem world are caused by its breakdown. And, naturally, how exciting it must be to be in a position to diminish some of these problems. Or one might be asked to recount some ways in which one’s language reflects one’s culture and disposes us to look at the world in a particular way. Inevitably, if the conversation continues, one is asked for details about how the way that the elements of our language are put together reflects and/or facilitates the uses to which language is put, in particular its use in conversational exchange. Frowns of skepticism inevitably appear when it is revealed that what most theoretical linguists do is construct abstract models of grammatical structure and that the connection between this enterprise and anything to do with interpersonal communication is remote at best. I have no doubt that the reason that the activity of professional linguists is often dismissed as irrelevant or obviously wrong-headed is because we have not lived up to the educated public’s idea of what linguists should be doing. Even the scholarly critique of linguistics shares elements of the public’s disapproval. Psychologists and workers in artificial intelligence, more often than not, urge us to abandon our obsession with models of abstract competence and focus directly on models of use. Anthropologists wonder aloud whether our pursuits will ever aid them in their attempt to unravel the intricacies of the interconnections of language and culture. And literary theorists feel that somehow our specialized knowledge of language ought to be more relevant to their concerns. So why is linguistics - in its mainstream manifestations at least - the way that it is? Why don’t we linguists take what is often misleadingly referred to as a more ‘human’ approach to our subject matter? As I see it, the answer is simple every major advance in our understanding of language over the past two centuries has involved abstractions away from the social and communicative factors relevant to its use. Uncontroversially, the modem field of linguistics dates from the discoveries about language that were made at the beginning of the nineteenth century. Research revealed that almost all of the languages of Europe, as well as many of those spoken in Persia and India, share too many resemblances to be attributed to chance. And furthermore, these resemblances were soon seen to be systematic. In words of identical or obviously related meanings, sounds in one language often correspond to sounds in another language. The only reasonable conclusion was that these languages share the same ancestor. As more and more sound correspondences were discovered, great progress was made in understanding the sound changes - misleadingly called sound ‘laws’ - by which daughter languages diverged from their common ancestor. By the middle of the nineteenth century it was recognized that these changes were to a significant extent independent of the culture, beliefs and level of development of the people who spoke the languages. And by the end of the century, the ‘Neogrammarians’ had concluded that the sound changes were both mechanical and fully regular. The discovery that language was autonomous in this respect was the first major step towards the current conception that systematic properties of language are independent of the social and communicative setting in which it is used. In other words, linguists had adopted the first ‘autonomy hypothesis’ for language. The second major revolution in linguistics took place at the beginning of the twentieth century. It is usually associated with the name of the Swiss linguist Ferdinand de Saussure, but in fact the central discovery of this revolution - the phonemic principle - was made by a number of different scholars in a number of different countries. This, the structuralist revolution, was in effect the extension of the autonomy hypothesis to synchronic aspects of linguistic structure. Saussure [l] advocated the concept of the ‘arbitrariness of the sign’ - the idea of an autonomous linking at the level of the word (or morpheme) between sound and

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meaning. This linking was part of ‘lungue’, the systematic and collectively-shared component of language, to be distinguished from ‘parole’, actual acts of speaking. Other structuralists extended langue to the phonological and word-class systems of language. By the end of the first third of our century, it was widely agreed that at least the phonological systems of all languages could be regarded as functioning as autonomous systems. While both theoretical and analytical problems remained, it seemed that highly systematic principles governed the distribution of sounds in every language. And just as in historical reconstruction, these principles could be applied in the absence of knowledge of the culture or communicative styles of the people speaking the languages. Furthermore, while no one ever doubted the usagebased factors, such as ease of articulation and perception, are responsible for some phonemic systems being more common than others, neither the methodology of phonemic analysis nor the actual principles arrived at in the course of analysis need to make reference to these factors. The publication of Noam Chomsky’s Syntactic Structures in 1957 [2] ushered in the third revolution. The scope of autonomous grammatical analysis was broadened again, as Chomsky convinced many linguists that even previously intractable syntactic relations were subject to insightful analysis in terms of a system making no reference to social or communicative factors. In this theory of generative grammar, syntax joined phonology and morphology as components of langue, which was rechristened ‘linguistic competence’ (and contrasted with ‘linguistic performance’). Furthermore, the complexity and abstractness of the system of competence arrived at in the course of analysis pointed to central aspects of the system being hard-wired in the human mind. The idea that grammatical principles form part of an innate universal grammar (UG) was perhaps the most dramatic leap of all away from the common sense view of language. We can summarize the essence of the third revolution in terms of its two central hypotheses, viz. the ‘autonomy hypothesis’ and the ‘innateness hypothesis’: The Autonomy Hypothesis (AH). There exists a system embodying knowledge of language (‘competence’), which, at least for adult speakers, can and should be characterized independently of language use (‘performance’) and the social, cognitive and communicative factors contributing to use. The Innateness Hypothesis the human genome.

(IH). Central aspects of this autonomous

2.2. Opposition

and innateness

to autonomy

system are provided by

At every stage in the development of the field, there has been a significant minority attempting to reassert the ‘common sense’ view of language. The best known and most consistent opponent of the Neogrammarians was Hugo Schuchardt (see especially [3]). He objected violently to the idea of mechanically applying sound changes, for which he felt “repugnance . . . from the very first” (41). He could not conceive of any significant aspect of language being divorced from the conscious mental and social life of its speakers. The structuralists, too, had their opponents. Here is Schuchardt on the langue-parole distinction: [T]here is no chasm and this transition sphere no clear line distinction must be

separating the individual from the collective, but a gradual transition from one to the other, is, moreover, purely superficial in nature Saussure concedes that in the syntagmatic can be drawn between facts belonging to langue and facts belonging to parole; but even this rejected. Nowhere does he make it clear to what degree the collectivity functions differently

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F. J. Newmeyer from the individual, nowhere does he indicate what characteristics distinguish organized language, the mechanism, the system, from parole Here, as elsewhere, his classificatory urge causes him to contradict himself; this dissonant note pervades the whole ingenious structure and splits it apart. ([4]: 4, translated in [5]: 35-36)

The principal defenders of the common sense view of language today are the majority of those who consider themselves ‘functional linguists’, or simply ‘functionalists’. Central to mainstream functionalism is the idea that the major features of grammar are motivated by the functions that language carries out, in particular its function in communication. For example, a generalization about word order might be attributed to the most orderly or efficient means of conveying information, the desirability of foregrounding or backgrounding events in the discourse, the speaker’s desire for economy, the hearer’s demand for clarity, or to cognitive propensities not specific to language, such as a general preference for iconic over arbitrary representations, and so on. Note how the remarks of Talmy Given, a leading functionalist, are, in effect, an assertion of the common sense view of the relationship between language and factors external to it: The dogma of autonomous syntax precludes asking the most interesting questions about the grammar of human language, namely, why it is the way it is; how it got to be that way; what function it serves, and how it relates to the use of human language as an instrument of information processing, storage, retrieval, and - above all - communication. ([6]: xiii)

In other words, functionalists

3. PREVIOUS

ATTEMPTS

reject both AH and IH.

TO ESTABLISH

AH AND IH, AND THEIR LIMITATIONS

Broadly speaking, there have been two types of argument adduced in the literature in support of AH and IH, which, for want of better terms, we can call ‘grammar-based’ and ‘external’. The following subsections exemplify both, and will explain why they have not met with universal acceptance. Section 4 will argue that evidence based on GD is largely exempt from the difficulties that have contributed to this lack of acceptance. 3.1. Grammar-based

arguments for AH and IH

How might one go about finding evidence for AH and IH from an examination of natural language data? Generally, linguists have followed a three-step process. The tist is to demonstrate that profound mismatches exist between grammatical form and external function, thereby calling into question the functionalist view that the former is dependent on the latter. The second step is to show that grammatical form itself is subject to elegant principles of wide applicability. The third step is to conclude from the abstractness and/or complexity of these principles that no conceivable mechanism of inductive learning could have resulted in their acquisition (the so-called ‘poverty of the stimulus’ argument). Thus, they must be innate. 3. I. I. Form-function

mismatches

and their implications

3. I. 1.1. Wh-constructions, case and autonomy Let me illustrate the three-step process with reference to English wh-constructions, that is, those in which a wh-phrase occurs displaced from its subcategorized position and fronted. Among them are the following: (1)

Wh-constructions in English: Questions: a. Who did you see?

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theory

Relative Clauses: b. The woman who I saw. Free Relatives: c. I’ll buy what(ever) you are selling. Wh (Pseudo) Clefts: d. What John lost was his keys. The mismatch between form and function in these constructions is striking. Formally they are, in relevant respects, virtually identical. In each construction type, the displaced &-phrase occupies the same structural position - the left margin of the phrase immediately dominating the rest of the sentence (in the terminology of the Government-Binding Theory, the ‘Specifier of CP’). Furthermore, the relationship between the displaced w&phrase and the gap with which it is associated is identical. In each case, for example, the gap may be indefinitely far from the w&phrase, with the relationship between the two subject to the Subjacency constraint:’ (2) (3) (4) (5)

a. b. a. b. a. b. a. b.

Who did you ask Mary to tell John to see _ ? *Who did you believe the claim that John saw _ ? The woman who I asked Mary to tell John to see _ . *The woman who I believed the claim that John saw _ . I’ll buy what(ever) you ask Mary to tell John to sell _ . *I’ll buy what(ever) Mary believes the claim that John is willing What John is afraid to tell Mary that he lost is his keys _ . *What John believes the claim that Mary lost is his keys _ .

to sell _

.

Clearly, then, it is possible to characterize the formal distribution of displaced w&phrases by simple structural generalization. Functionally, however, each of the four different wh-phrases plays a different role and has a different motivation. Given [8] gives a focus-based explanation for the fronting in simple whquestions: sentence-initial position serves to focus the request for a piece of new information. If Haiman [9] is right, however, the fronting in relative clauses has nothing to do with focusing. Rather, the iconic principle, ‘Ideas that are closely connected tend to be placed together’, is responsible for the fronting of the relative pronoun to a position adjacent to the head noun. Free relatives, by definition, have no head noun, so why is the wh-phrase fronted? The explanation in [8] is an historical one: their diachronic origins are in full relatives that have lost their heads, and the fronted pronoun survives as a relic of their headed stage. Functionally, pseudo-clefts are different still. As Prince [lo] argues, the clause in which the wh-phrase is fronted represents information that the speaker can assume that the hearer is thinking about. But the function of the wh-phrase itself is not to elicit new information (as is the case with such phrases in questions), but rather to prepare the hearer for the focused (new) information in sentence-final position. In short, we have a one-many relation between form and limction, with form subject to a principle of its own (Subjacency). Furthermore, the formal principles involved in wh-fronting interact with other formal principles involved in other types of constructions. That is, not only do wh-constructions have an internal formal consistency, but they behave consistently within the broader structural system of English syntax. So, for example, consider the assignment of nominative and objective case in English. At first glance, there seems to be a simple generalization: displaced NPs bear the case of their surface position; displaced wh-phrases bear the case of their subcategorized (underlying) position.*

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(6) (7)

F. J. Newmeyer

a. b. a. b.

She / *Her was seen by Mary. She I *Her is easy to please. *Who / Whom did you see? Who I *Whom saw Mary?

How can we explain the facts of (67)? A classical generative analysis derives them from the following ordering of the rules of Noun Phrase Movement (i.e. Passive), Case Assignment, and W/r-Movement (see [l 1]):3 (8)

a. Noun Phrase Movement b. Case Assignment c. W/z-Movement

This kind of interaction between ‘movement’ processes and case assignment points directly to the correctness of AH. That is, we find a systematic set of structural interactions stated in formal, not functional (or semantic) terms. As it turns out, the facts are more complicated and more interesting than those sketched above. The case of the w/z-phrase is not in fact that of its subcategorized position; rather, it is that of the last position that it occupies before &-movement. Note the following sentence, in which the subject of a passive has been wh-fronted. The case of the wh-phrase is nominative (the case of the subject of the passive), not objective (the case assigned by the verb that subcategorizes the wh-phrase): (9)

Who / *Whom do you think _

was seen _

by John?

This result can be achieved if we assume that syntactic rules apply cyclically. The principle of cyclic application of transformational rules, a formal principle par excellence, is one of the most long-standing and best motivated principles of formal grammar (for a summary, see [ 141). In short, the principles involved in wh-constructions are part and parcel of an autonomous structural system. 3.1.1.2. From autonomy to innateness Once we have agreed that principles like Subjacency and the cyclic application of transformational rules are part of our grammars, the question naturally arises as to how we might have come to possess them. The standard strategy is to argue that they could never have been learned inductively, and thus must be part of the innate cognitive make-up that every child brings to the task of language acquisition. Consider, for example, the argument put forward in Hoekstra and Kooij [ 151 defending the innateness of Subjacency. Since this constraint prohibits the formation of wh-questions if a wh-phrase intervenes between the filler and the gap, it predicts correctly that (1 Oa) is ambiguous as to the scope of where, while (1 Ob) is not. Note that in (1 Oa), where can refer both to the place of John’s saying and the place of getting off the bus, while in (1 Ob), where can refer only to the place of John’s asking: (10) a. Whcrei did John say ti that we had to get off the bus ti? b. Wherei did John ask ti whether we had to get off the bus *ti? They argue that positive evidence alone could hardly suffice to enable the child language learner to come to the conclusion that (1 Ob) does not manifest the same ambiguity as (1 Oa) the abstractness and complexity of the principle and the paucity of direct evidence bearing

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directly on the principle guarantee that the child could never figure Subjacency out ‘for itself. Thus knowledge of the permissible intervening structure between a wh-phrase and its coindexed gap must be pre-wired into the language learner. 3.1.2. Resistance to grammar-based arguments for AH and IH. So the question is, why have grammar-based arguments leading to AH and IH not been universally accepted? The following subsections address this question. 3.1.2.1. Leaky grammars As is suggested by the multiplicity of competing syntactic theories, both generative and functionalist, the correct theory of grammar is vastly underdetermined by the evidence provided by natural language data. Furthermore, grammatical evidence is notoriously messy. As Edward Sapir was famous for observing: “All grammars leak”. This leakiness is at the core of the difficulty of establishing knock-down arguments either for or against AH or IH using grammatical data alone. A functionalist would not deny that form and function can diverge significantly - no reasonable linguist could deny that - but, rather, would point out (correctly) that the relationship between them is nonrandom. That is, in general similar structures subserve similar functions. Perhaps not all languages signal questions by fronting wh-phrases and perhaps not all fronted wh-phrases signal questions. Nevertheless, the functionalist argument goes, postulating AH renders it impossible to capture such links between form and function that do exist. Now, strictly speaking, such is not true - any comprehensive theory of grammar has to flesh out the forn-function interface and, in doing so, capture the regularities between them. But the fact that generative grammarians, in general, have shown little interest in the nature of these regularities has given ammunition to the functionalist rejection of AH. Also, the functionalist literature is replete with counterarguments to those supporting AH (though I am not aware of any attempted refutation of the above dealing with the case marking of wh-expressions). For example, Deane [ 161 has argued that Subjacency effects can be derived from a combination of semantic and processing principles, and therefore do not demand an appeal to autonomous grammar. While neither I nor most other generative grammarians have been swayed by such purported refutations of autonomy, nobody would deny that grammatical data are so complex that knock-down arguments for or against one broad theoretical orientation are difficult to construct. 3.1.2.2. Principled objections to introspective data The question of the correctness of AH is sometimes linked to the question of the sources of the data upon which linguistic theory is constructed. Uncontroversially, this data has consisted in very large part on the intuitive judgments of the well-formedness of sentences by native speakers. A number of critics have complained that this fact disqualifies a generative grammar as being a model of anything other than those intuitions - that is, if one bases one’s theory on introspective judgments, then the autonomy thesis will follow as a logical consequence. For example: Artificial-sounding sentences, in isolation of communicative fimction and communicative context, became the stock-in-trade of linguistic evidence [for generative grammarians], to be analyzed, dissected and ‘explained’. On the basis of such ‘data’, an independent level of grammatical organization - autonomous syntax was postulated, with its so-called ‘properties’ studied in great depth, whose imputed existence bore no relation to natural language facts. ([6]: 25)

Givbn is surely wrong if what he means is that reliance on introspective data somehow leads irrevocably to AH (and, by extension, to IH). For example, virtually all of the data appealed to

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in the framework known as ‘cognitive grammar’ ([17-l 81) is introspective, yet this framework interprets the data in such a way as to conclude that AH is ill-founded. Indeed, the data cited in typical functionlist work tend to be far more introspectively based than the Given quote would imply. The null hypothesis is that there is only one mentally represented model of grammar - not one that governs the introspective judgments that speakers make and another that is involved in, say, language processing or the act of communication. Furthermore, evidence from the latter domains is, in principle, just as relevant to the nature of grammatical theory as that from the former. As Chomsky has noted: If we accept - as I do [the] contention that the rules of grammar enter into the processing mechanisms, then evidence concerning production, recognition, recall, and language use in general can be expected (in principle) to have bearing on the investigation of rules of grammar ([19]: 200-201)

Another objection to the use of introspective data is based on the widespread belief among psychologists, not to mention a broad spectrum of linguists themselves, that introspective judgments of acceptability are too unstable to serve as the primary data base for theory construction (for a survey, see [20]). But such a view appears to be false. Cowart [20] has constructed experiments that indicate that native speakers produce a remarkable consistency of judgments, even where the most subtle syntactic phenomena are at stake. 3.1.2.3. Problems with poverty-of-the-stimulus based arguments As far as IH is concerned, if the autonomous principles do not exist, then poverty of the stimulus arguments to explain their existence become pointless. Indeed such arguments have, in and of themselves, been called into question. An appeal to the poverty of the stimulus will be convincing, as John Hawkins has frequently reminded us [22,23], only to the extent that we are sure that positive evidence would not suffice for learning. The problem is that we do not really have a theory of what is learnable from positive evidence (for more on this point, see [24]). Thus the claim that no child could come to acquire some feature of his or her language without innate guidance is not based on the failure of some particular concrete and widely-accepted theory of learning; rather, it is based more on the plausibility that no such theory could possibly exist. Furthermore, as Matthew Dryer has pointed out (personal communication) while poverty of the stimulus arguments might lead irrevocably to innateness, they do not lead necessarily to innate principles of UG. That is, while the acquisition of the contrasts in (1 Oa, b) might suggest that the child brings to the language learning process more than the ability to make simple generalizations from observed input, there is no logical necessity for the conclusion that a specifically linguistic faculty (i.e. an innate universal grammar) is at work, rather than some sophisticated general cognitive faculty or some more specific faculty not restricted to language. In summary, arguments for AH and IH that appeal to grammatical data alone have not won general acceptance. Let us now turn to external arguments. 3.2. External

evidence for AH and IH

One might assume that there is a much more direct way to test for the correctness of AH and IH than by the intricate chain of argumentation that is involved in an appeal to grammatical data. One would predict that, if grammatical knowledge is indeed organized along the lines posited in generative grammar, AH would manifest itself behaviorally. That is, we would find clinical and experimental evidence for the dissociability of grammar (or a component of grammar) from other faculties involved in language. Since dissociations could hardly be

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‘learned’ (in the ordinary sense of that term), their existence would seem to provide support for both AH and IH. 3.2.1. Dissociations of grammar and other faculties. External evidence for AH and IH has been reported in the literature based on the dissociation between grammar and other cognitive faculties. For example, a number of researchers have reported on remarkable syntactic abilities in children who are otherwise severely impaired cognitively [25-281. Likewise, Curtiss, Fromkin and Yamada report dissociations between syntactic abilities and hierarchicallyorganized construction tasks, thereby calling into question the idea of one supramodal hierarchical processor [29, 301. Other investigators have pointed to agrammatic aphasia as a specifically syntactic impairment [31-331. Aphasic patients have been found who have lost the ability to encode thematic roles within the grammatical system, but who maintain knowledge of the conceptual relations themselves [34]; those with lexical and semantic deficits, but with relatively little grammatical loss [35]; and those with massive pragmatic deficits leaving the grammatical system intact [36]. To point to a more concrete example, Breedin and Saffran [37] report on a brain damaged patient who has a clear dissociation between semantics and syntax - he is unable to look at a picture of a cow or a horse and tell you what it is, or anything about a cow or horse. But if shown two pictures, one where a horse is kicking a cow and another where the cow is kicking a horse, he can use syntax to point to the correct animal. That is, if he is presented with the sentence ‘The cow is kicked by the horse’ and asked to point to the ‘cow’ or the ‘horse’, he will do this 100% correctly. Aphasias among those who use signed languages provide particularly striking cases of the dissociability of syntax. For example, Poizner et al. [38] have found aphasic signers of American Sign Language (ASL) who manifest signing (i.e. syntactic) deficits, but have no general problems in making hand gestures, suggesting a purely syntactic ‘module’ involved in ASL. Dysphasias also support the idea of a purely syntactic module. Kempler et al. [39] report preserved syntax among Alzheimer’s disease patients whose semantic and general cognitive abilities were severely degraded and [40,41] report an analogous effect for those affected with Prader-Willi syndrome. And finally, the brain’s measurable electrical emissions appear to distinguish syntactic from semantic processing, as is demonstrated by event-related brain potentials (ERPs) elicited during comprehension. ERPs are patterned voltage changes in the ongoing electroencephalogram that are time-locked to the onset of a sensory, motor or cognitive event. ERP measurements of brain activity have indicated a negative potential of 400msec (N400) involved in the perception of semantic anomalies [42] and N125 and P600 effects for syntactic violations ([43] and [44], respectively). 3.2.2. Challenges to dissociation-based evidence for AH and IH. All the foregoing appears to be strong direct evidence for AH and strong indirect evidence for IH. So, again, one must ask why it has not led to the universal acceptance of these conceptions. The issue boils down to the robustness of the separation of syntax from other aspects of language that has been reported in these studies. Apparently, it is rare, for example, for any aphasic patient to manifest o&y a syntactic deficit, Alzheimer’s patients do have some syntactic loss, and so on. Lieberman [45] and Mtiller [46] conclude that such facts refute a UG module such as is postulated in generative grammar, i.e. they refute AH and IH.

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It is quite instructive to observe what they propose in its place. Since they can hardly challenge the idea that there is, indeed, a significant detachability of syntax, they cannot reject tout court its bearing an independent neurological reality. So, for example, Lieberman [45] acknowledges that “it is quite possible that some aspects of the brain mechanisms that regulate the syntax of human language have nothing to do with motor control’ and goes on to say that: Natural selection over the past 150,000 to 200,000 years could have produced neural structures dedicated to syntax. Noam Chomsky’s [47] intuitions are, in part, correct - human beings undoubtedly have brain mechanisms that genetically code some aspects of the possible syntactic rules of all human languages. (p. 109)

Mtiller hedges as well. For example, he writes of “a gradual specialization of the neural basis of language during hominid evolution and human ontogeny” (p. 15), a phraseology quite compatible with language as a whole forming a distinct cognitive system. And as far as syntax is concerned, it is “a nondiscrete cognitive specialization that may be selectively disturbed or developed in abnormal ontogenesis” (p. 25). While there may be “regional functional specificity . . there is little evidence for autonomously functioning ‘modular’ subsystems” (P.3 1). One wonders, then, what the difference is between Lieberman‘s and Miiller’s positions on the one hand and what they perceive Chomsky’s to be on the other. As far as I can tell, at this level of generality there is only one: whether the neural structures implicated in syntax form a discrete localizable mass or whether they do not. But since Chomsky (and those who share his perspective) have never postulated that they must do so, the positions are fully compatible. The evidence cited by Lieberman and Mtiller serves only to cast into doubt a strong localist approach to UG - an approach that has never, to my knowledge, been advocated.4 If strong localism is untenable - as it clearly is -- then it stands to reason that dissociations between syntactic and other abilities will rarely be complete. Nevertheless, the fact that few of the dissociations between grammatical abilities and extragrammatical linguistic abilities are fully clean has served to undercut their utility in establishing the correctness of AH and IH. 3.2.3. Grammarians’ generative grammarians

own reluctance to appeal would agree with Chomsky’s

to external evidence. opinion that:

Probably

most

In the real world of actual research on language, it would be fair to say, I think, that principles based on evidence derived from informant judgments have proved to be deeper and more revealing than those based on evidence derived from experiments on processing and the like, although the future may be different in this regard. ([19]: 200)

Despite his speculations about the future, six years later Chomsky increasing role in the use of external evidence:

could not point to an

As an objection of a narrower sort, one can take it seriously as an argument that the evidential base is too narrow to carry conviction; one who believes this might ask what other kinds of evidence would strengthen or undermine the theories we are led to construct on the basis of the (not inconsiderable) evidence that we can now readily obtain. In practice, what has been produced along these lines has not been very informative, but certainly any improvement in this regard will be welcome. ([47]: 260)

And a decade later, it must still be acknowledged that experimental and clinical evidence has played an insignificantly small role in the formulation of grammatical principles or in the choice of competing principles. The question is why this has been the case. If such evidence does point to the correctness of AH and IH, then why don’t we find more grammatical research papers appealing to such evidence in arguing for a particular grammatical analysis? There are two principal reasons,

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aside from the obvious ease of collecting data introspectively. The first is that for the most part, any language loss observed as a result of some developmental disorder or as a result of trauma tends to be too broad-grained to be useful for identifying particular grammatical conceptions. Cases of aphasia, for example, have indeed been reported whose plausible interpretation is a preservation of grammar in the face of semantic or pragmatic loss, or vice versa. However, there are few if any convincing cases pointing to preservation or loss of some theoretical entity internal to grammar.5 Secondly, experimental attempts to establish or refute the cognitive basis for some grammatical rule or principle have, in general, not proved successful. For every experiment whose results are taken to confirm the psychological reality of the vowel shift rule in English phonology or of a passive transformation or of some principle of UG, there is another whose results seem to lead to the precise opposite conclusion. The problem is that too many cognitive systems of diverse and (in general) unknown types intervene between a subject’s performance on, say, a recall test and his or her mental grammatical representations. We simply have no way of judging, given our present knowledge of the nature of mind, which of these systems is primarily responsible for a subject’s experimentally-induced behavior. Indeed, it seems quite plausible that fewer such systems contribute to introspective judgments of sentential acceptability than to a subject’s performance in a typical laboratory experiment. If such is the case, then the traditional practice of grammarians in giving priority to introspectivelycollected data is - ironically enough - well motivated psychologically.

4. GENETIC

DYSPHASIA:

COMPELLING

EVIDENCE

FOR BOTH AH AND IH

The significance of genetic dysphasia is that it provides the cleanest evidence ever adduced for the correctness of both AH and IH. The following subsections will defend this point. 4.1. Genetic dysphasia

and AH

GD is, by definition, a specific language impairment (SLI) transmitted genetically. And SLI is, by definition, a language disorder unaccompanied by nonlinguistic deficits, such as an abnormally low IQ, a hearing deficit, a brain injury, a significant medical history, environmental deprivation, or an obvious emotional or behavioral disturbance. One’s first thought, therefore, might be that any case of SLI (genetically transmitted or not) would ipso facto support AH.6 Things are not so simple, however. SLI is defined broadly enough to encompass language disorders that are not necessarily deficits in linguistic competence per se, and therefore may have no bearing whatever on AH. For example, deficits to the peripheral mechanisms involved in language production and comprehension are (or can be) SLIs. But unless in some specific case one is able to successfully demonstrate that the deficit leaves the competence system intact (no easy task!), that case would neither provide evidence for or against AH. In other words, not every case of SLI provides evidence for AH. But it is equally the case that a language impairment that is accompanied by cognitive or other nonspecifically linguistic deficits (and is therefore, by definition, not a case of SLI) is not necessarily evidence against AH. For example, a dysphasia that always happened to be accompanied by, say, problems with articulation or cognition would weigh against the correctness of AH only if the problems in grammar followed as a consequence of those external to grammar. If the same underlying factors (genetic or otherwise) were at the root of all the impairments, then the facts would present no challenge to the notion of an autonomous grammatical system.

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Indeed, it is within the realm of plausibility that a prior degree of grammatical knowledge is a prerequisite to the development of the full set of normal cognitive abilities. Thus, if we find a case in which grammatical and cognitive deficits co-occur, it might well be the former (i.e. an impairment to the autonomous grammatical system) that is the root cause of the latter. In the past few decade:;, hundreds, if not thousands, of individuals have been diagnosed with SLI, providing an immense potential pool to test the hypothesis that a grammatical system can be impaired in the absence of deficits in other capacities, whether linguistic or nonlinguistic. Unfortunately, it is all but impossible to extract relevant evidence for this hypothesis from the great majority of such cases. Not only are diagnoses arrived at on the bases of wildly different criteria, but only rarely are enough grammar-probing tests applied to allow firm conclusions to be drawn.’ In the best studied case of SLI of all, however, the evidence for a differential loss of grammatical competence seems incontrovertible. This is the working-class British family described in [55] and elsewhere, and referred to in the literature as ‘the KE family’ (or simply as ‘the K family’). With the exception of some problems with articulation (see below), the only deficit shared by all affected members of this family is a partial - and consistent - loss of grammatical function. All attempts have proved fruitless to circumvent the conclusion that the locus of their deficit is the autonomous grammatical system. To begin with, environmental causes can be ruled out. There is no difference in the broader communicative context that might account for why one family member is afflicted and another not: The fact that these close interactions occur between the impaired and the unimpaired members of the family means that the impaired subjects are receiving constant linguistic input from the speakers who do not have any linguistic impairment and yet they are never able to construct a normal grammar. The fact that they were all raised in the same neighborhood insures that they all have the same dialect of English, therefore differences in their linguistic performance cannot be attributed to a difference in dialect. ([56]: 1)

Furthermore, the dysphasia affects the formal features of language only, leaving those manifesting the syndrome with no loss of ability in the conveying or understanding of meaning or in the pragmatics of language use. For example, loss of the ability to produce tense markers implies no decreased ability to mentally represent ‘presentness’ or ‘pastness’ ([57]); the loss of ability to produce number markers implies no decreased ability to differentiate semantic singularity and plurality [58, 591; and so on. As might be expected, there have been attempts to attribute the deficit manifested by affected KE family members to systems at work in the use of language, and thereby undercut the theory that it is the grammatical system per se that is affected.8 For example, Leonard [62-651 has hypothesized that an auditory processing deficit is responsible for the dysphasia - subjects have difficulty processing morphological inflections because they are not acoustically salient. However, as Goad and Gopnik [66] and Gopnik [67] have shown, such an explanation cannot be correct. Affected members of the KE family perform excellently on phoneme-recognition tasks, and, moreover, have no difficulty perceiving unstressed word-final segments that mimic the form of inflectional suffixes (e.g. the final alveolar in words like wand). Fletcher [68, 691, on the other hand, posits an articulatory deficit - affected individuals, for example, lack the ability to produce the final alveolar consonant in past tense forms. But Gopnik [70] reports that clinical assessments by a neurologist and a speech-language pathologist indicate no reduction in range or movement or tone of the mouth or tongue musculature, thereby ruling out a diagnosis of dysarthia, as defined in [71]. It is true that the affected members of the KE family manifest problems in articulation. But these problems could not be the root cause of their grammatical impairment - no deficit in articulation could explain

Genetic dysphasia

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59

theory

why they make errors with suppletive past tenses (was, went) and with irregular pasts, regardless of the sound that happens to occur in final position (took, drove, got, swam, etc.).’ And, as observed by Gopnik and Goad [61], ‘it is very hard to see how articulatory problems could prevent them from making correct grammaticality judgments or ratings which require them to just nod yes or no or to circle a number’ (p. 109). In short, there seems to be no avoiding the conclusion that the dysphasia affecting the ICE family is a condition affecting the grammatical system per se, and, by virtue of that fact, there seems to be no avoiding the conclusion that such a system must exist. 4.2. Genetic dysphasia

and IH

Let us turn now to evidence for IH. It has been known for some time that SLI tends to run in families [73, 741. Researchers have now had the opportunity to study the linguistic deficits of familial SLI manifested by speakers of four different languages: English (16 impaired individuals in three generations of the KE family); Japanese (several children who have a positive familial history of SLI - [75]); Inuktitut (a single speaker from a family in which SLI has been reported in three generations - [76]); and Greek (18 children, nine of whom have a positive family history of SLI - [77]). Now, as observed by Pinker ([48]: 48849) the fact that a behavioral pattern runs in families does not prove that it is genetic: ‘Recipes, accents, and lullabies run in families, but they have nothing to do with DNA’. Nevertheless, no environmental explanation seems forthcoming for why approximately half the members of the ICE family are affected, including one fraternal twin. Indeed, the heritability of (some types of) SLI is suggested by its increased occurrence in monozygotic, as compared to dizygotic, twins. Table 1 (reprinted from [78]: 229) illustrates. In addition, there is a ready genetic explanation for the distribution of the language-impaired and the nonimpaired in the ICE family. As a geneticist has noted: [T]he relatively clear-cut difference between affected and unaffected members [of the family] and the occurrence of 15 definitely affected members out of 29 over three generations affecting both sexes equally, is highly indicative of autosomal dominant inheritance Such a concentration of a rare distinct disorder in 15 members of one family makes polygenetic and multifactoral inheritance very unlikely. ([82]: 5455)

In other words, we have strong evidence for the genetic grammatical traits, that is, we have evidence for IH. 4.3. Genetic dysphasia

transmission

of specific

strictly

and the external evidence problem

Studies of the language difficulties of genetic dysphasics are to a significant degree immune to the problems posed by external evidence that were discussed above in Section 3.2.3. To begin with, the informal judgments of sentential acceptability by members of the KE family jibe fully with their experimentally-induceu ratings of sentences as ‘natural sounding’ or ‘unnatural sounding’. But importantly, for linguistic variable after linguistic variable, tests have led to identical conclusions with respect to subjects’ mastery of that variable. Unlike one study which might show that English speakers have a productive command of the dative alternation

Table 1. Percent of concordance Monozygotic 80 86 89

in twin pairs with SLI

Dizygotic

Source

38 48 48

[791 [801 [811

60

F. J. Newmeyer

and another which might show that they do not, there is a remarkable degree of consistency in the interpretation of the studies of the gross linguistic abilities of members of GD-affected families. lo For example, no one disputes that the affected members of the KE family have difficulty with morphological tense. Gopnik [56] reports that eight very different tests lead to this conclusion: 1. A tense changing task; 2. A task involving the rating of the degree of wellformedness of sentences; 3. An analysis of tense in spontaneous speech; 4. A task requiring auditory discrimination of monomorphemic words with the same phonological form as past tense words; 5. Self-correction in spontaneous speech; 6. Observation of subjects’ command of tense and agreement in elicited narratives; 7. Observation of subjects’ use of temporal adverbs; 8. A longitudinal analysis of tense in a written notebook. In other words, with GD, as opposed to many other sources of external evidence, we have a pretty clear picture of what the facts are that are in need of explanation. The one (minor) fly in the external-evidence ointment is the fact that some dysphasics do seem to be able to produce what appear to be correct tense, number, etc., markings from time to time. Paradis and Gopnik [83] demonstrate that their apparent success results from their having adopted compensatory strategies involving the application of metalinguistic knowledge and by storing regularly inflected lexical items as unanalyzed forms in declarative memory. The principal support for the idea that the correct forms are a product of controlled explicit knowledge, rather than the application of competence rules, comes from the existence of frequency effects. The more common the form, the more likely they are to use it correctly, while they invariably fail to provide the correct inflections on nonsense words. What needs to be addressed, of course, is the relationship between the aspects of grammar that are differentially affected in dysphasic speech and the theoretical constructs arrived at in the course of grammatical research. It is to that question that we now turn.

5. GENETIC

DYSPHASIA

AND THEORETICAL COMPETENCE

MODELS

OF GRAMMATICAL

In this section, I will address the question of whether and how GD bears on models of linguistic competence. There are really two inextricably intertwined issues involved here. One is whether existing grammatical theories suffice to single out the grammatical factor or factors implicated in GD. The other is whether and how the grammatical deficits observed in individuals with GD might be brought to bear on the construction and evaluation of grammatical theories. Both will be addressed. 5. I. Some preliminary

cautions

In attempting to determine whether a particular grammatical theory can capture the deficit reported in GD, we are immediately confronted with the fact that there exists an embarrassing multitude of competing theories of grammar, each in a state of flux, and each loose enough to accommodate virtually any generalization derived from observed instances of exceptional language. Therefore any pronouncement about how the constructs internal to some particular grammatical model ‘explain’ some observed deficit is likely to be countered by ripostes from advocates of a rival model, who will demonstrate that their constructs do just as well. Furthermore, since the shelf life of most proposed grammatical principles is a decade or less, such explanations are saddled with a built-in expiry date that renders them inapplicable with the inevitable advent of the replacement model and its different set of principles. In the ideal case, the principles of the replacement model subsume those of the earlier model,

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with little or no loss of generality. This has happened, to be sure: consider the replacement of the constraints proposed in Ross [84] by the Subjacency principle ([7]) and that of the TensedS-Condition and the Specified Subject Condition [7] by Principle A of the Binding Theory [ 121. Hence any explanation of exceptional language appealing to, say, the Specified Subject Condition translates easily into a binding-theoretic explanation. But more often than not, the generalizations expressed by a principle of a particular framework are unformulable in its replacement. For example, this appears to be the case with the notion of ‘government’, which (as the name implies) was central to the GovernmentBinding Theory [12]. Despite its broad range of applicability, it is unformulable in the Minimalist Program [85]. The same can be said about the levels of D-Structure and S-Structure of the former theory, which have no consistent correspondents in the latter theory. Thus one is left wondering what can be salvaged of an explanation of the deficit observed in agrammatic aphasic speech that appeals to the government of items at S-Structure, such as that put forward in Grodzinsky [50]. The history of the field of second language acquisition research provides an object lesson in the dangers of being too quick to appropriate the theoretical constructs of the moment (for more discussion, see [86]). Consider, for example, how specialists in this field have accounted for the fact that English learners of Spanish frequently produce the error el llueve ‘it is raining’, with an illegitimate subject pronoun. Different decades have produced different explanations, each based on the theoretical vocabulary of the period: in the 1950s the student transferred the ‘habit’ of obligatory subject pronouns from English; in the 1960s she failed to learn the Spanish transformation of Subject Pronoun Deletion; in the 1970s she failed to learn that Perlmutter’s obligatory subject filter was inapplicable to Spanish; in the 1980s she improperly fixed the Null Subject parameter; and now, in the 1990s she has failed to master the generalization that the Case features of Tense in Spanish are weak. But it is hard to resist the conclusion that few of these successive analyses represented an advance in our understanding of the learners’ errors, and were rather little more than a mere appropriation of currently fashionable terminology. I certainly wish to avoid giving the impression that I feel that GD-researchers shouldn’t look to grammatical theory as means of explaining the nature of the deficit. Given its obviously grammatical nature, it would be irresponsible not to explore the relevance of the grammarians’ latest conceptions. But rather, one should exercise extreme caution in concluding from the (possibly chance) fact that some construct internal to the latest model of grammar appears to describe some aspect of the deficit that we have thereby made a giant step toward explaining its grammatical basis. 5.2. The grammatical

deficits observed in GD

Before we can confidently attribute dysphasic speech to the loss of one or more principles of grammar, we need a good characterization in broad descriptive terms of the grammatical errors committed by those afflicted. While a complete characterization is still pending, Table 2 lists the areas of grammar in which most evident errors occur in the speech of the English, Japanese, Inuktitut and Greek dysphasics. (a-n) of Table 2 are, for the most part, evident to even nonlinguistically trained investigators and easy to test for. Deficits have been observed in other areas of grammar as well, though they have not been subject to extensive investigation. These include, for example, problems with wh-clauses, comparatives, quantification, and ‘a broad range of [other] difficulties in morphology, syntax, and phonology’ ([57]: 109). Even confining our attention to (a-n) (i.e. without worrying about ‘the broad range of other

62

F. J. Newmeyer Table 2. The grammatical

a. b. c. d. e. f.

i? i. j. k. 1. m n.

deficits observed

in genetic dysphasia

The morphological marking of tense (e.g. Even, day he walk home). (Reported for English, Japanese, Inukitut, Greek.) The morphological marking of number (e.g. three book). (Reported for English, Inuktitut, Greek.) The morphological marking of gender. (Reported for English, Inuktitut, Greek.) The morphological marking of modality / aspect (e.g. this one is look). (Reported for English, Japanese, Inuktitut, Greek.) The morphological marking of person. (Reported for Inuktitut, Greek.) The morphological marking of adjectival comparison (e.g. John is big than Mmy; mm-e bigger). (Reported for English.) The morphological marking of case. (Reported for Japanese, Greek.) The morphological marking of passives and / or causative% (Reported for Japanese, Inuktitut, Greek.) The morphological marking of nominalizations and locative expressions. (Reported for Inuktitut.) The formation of complex verbs by syntactic affixation and the formation of vet&verb affixes. (Reported for Japanese, Inuktitut.) Agreement involving the mass-count distinction (e.g. I play musics and We are going to ride some bicycle). (Reported for English.) Derivational morphology (e.g. the inability to relate proud and pride). (Reported for English, Greek.) Prosodic assignments, treating the maximal size of a derived prosodic word to be equivalent to the size of the minimal word (e.g. p&e&al, cigental). (reported for English.) Morphophonemic processes (e.g. voicing across morpheme boundaries). (Reported for English, Japanese.)

difficulties’), it is clear that they do not point to the loss of a single principle or system of principles that has been put forward in any model of grammar ever proposed. There is no known theoretical construct, for example, responsible for gender marking, derivational morphology, and the maximal size of a prosodic word. This fact, in and of itself, does not limit the plausibility of a genetic explanation for the grammatical loss observed in GD for two reasons. First, one would naturally assume that pleiotropy (the multitude of phenotypic effects triggered by a single gene), would be as rampant in the genetic determination of grammatical competence as in that of any other type of inherited trait. Thus, the suppression of the effects of a single gene might impact, say, both a syntactic principle and a phonological principle. Indeed, it is probable that entirely nonlinguistic traits are controlled by the same gene that is at work in GD, thereby explaining why many dysphasics manifest nonlinguistic disorders. l1 Second, genetically-transmitted abnormalities are frequently not confined to a single gene, but to several linked ones that work in concert with each other, each of which is responsible for a different trait or set of traits. Thus it is within the realm of possibility that GD might affect linked genes, one controlling a syntactic principle and another a phonological principle. In any event, as Pembrey [82] cautions, identifying the gene implicated in GD would not thereby identify ‘a gene for speech’, and certainly not ‘the gene for speech’ (p. 53). What is apparently the case is that GD involved the suppression of the effects of a gene (or set of genes) that determine the neurological structures subserving the acquisition of certain aspects of grammar. Such an idea receives support from the discovery of anatomical abnormalities in the brains of some individuals with SLI: Magnetic resonance imaging scans of specifically language-impaired (SLI) boys were examined The distribution of perisylvian asymmetries in SLl subjects was significantly different from the distribution in controls (P,: 0.01) These neuroanatomical findings suggest that a prenatal alternation of brain development underlies specific language-impairment. ([87]: 52)

Even if GD did turn out to be the result of the genetic suppression of a single grammatical principle (an unlikely event, to be sure), that does not mean that the behavioral effects of this disruption would be narrowly manifested in terms of a single class of grammatical errors. Grammars are complex tightly integrated systems in which, as most linguists see things, there

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are sequential feeding relationships among their components. That is, the output of some Principle A might form the input to some Principle B, whose output in turn might feed some third Principle C. Hence a genetic disruption of A would have consequences for the effects of C, even though the genetic basis for C itself might be fully intact. Given the above cautions, it is remarkable how much the deficits represented in (a-n) have in common. (a-k), in particular, have the potential for being a unified phenomenon, since they all pertain to inflectional morphology and associated agreement phenomena. Furthermore, they manifest themselves in all four of the languages for which GD has been documented: English, Japanese, Inuktitut and Greek. (l-n), on the other hand, seem more idiosyncratic, both crosslinguistically and in their robustness within any one language. For example, problems with derivational morphology have been reported for English and Greek subjects, but not for Japanese or Inuktitut. And even for English speakers, the same subjects who cannot manage an (inflectional) past tense or plural suffix have no trouble with derivationally-inflected words like nation, possible and growth.12 Likewise, nonstandard prosodic assignments have been reported only for English speakers and morphophonemic problems only for English and Japanese speakers. And here too we do not appear to find an across-the-board deficit. That is, while loss of a morphophonemic rule has been appealed to in the explanation of why dysphasics have trouble deciding whether to form comparatives with more or with inflectional -er [91] I am not aware of any general problem in their morphophonemic abilities. As far as I am aware, for example, they assimilate the morphophonemic nasal consonant across the morpheme boundary correctly in words like immoral, illegal, incompetent, irresponsible, and so on. Clearly, then, a reasonable working hypothesis is that whatever grammatical principle or system of principles is implicated in inflection and agreement is the primary candidate for genetic disruption. What might this principle or system of principles be? Let us review some suggestions and discuss their more evident difficulties. 1. The failed parameter setting hypothesis [62; 921). GD grammars have incorrectly set the Null Subject parameter, thereby accounting for mistakes in tense inflection. As it is stated, this hypothesis greatly underdetermines the deficit observed in GD, since tense is only one of many grammatical constructs that are impaired. No approach within the (pre-Minimalist) Government-Binding theory, to my knowledge, ever proposed a single parameter that could capture the deficits observed in GD. 2. The missing features hypothesis [93]. GD grammars lack the obligatory marking of grammatical features, and thus the marking of tense, number, and so on will be perceived as optional. In other words, just as a normal person might produce a passive instead of an active, a dysphasic would (randomly?) produce a grammatical feature or not produce one. There appear to be two major difficulties with this idea. First, it suggests that when a dysphasic gets a tense or number inflection right, a ‘normal’ grammar is responsible. However, the evidence points to affected individuals never being able to apply the relevant rules in their grammars. Instead, superficially correct forms are due to their applying a grammar-external compensatory strategy (see Section 4.3). Second, the notion ‘grammatical feature’ is too loose to predict what dysphasics can and cannot do. Features of various sorts are omnipresent in a wide variety of current conceptions of grammar, yet the deficits reported are (to whatever degree) selective. For example, features distinguish pronouns from anaphors (e.g. he wushes him from he washes himselj) and masculines from feminines (e.g. he holds him from he holds her), yet [58] report no difficulties with these distinctions. 3. The absent morphological rule hypothesis [58]. GD grammars are missing specific morphological rules, such as ‘add /-ed/ to form a past tense’, ‘add /-s/ to form a plural’, etc. As

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F. J. Newmeyer

noted in Ullman and Gopnik [88], this hypothesis predicts incorrectly that dysphasics should have no problems with irregular forms not generated by the rule. A further disadvantage is that it would appear to imply that there is a separate deficit for each incorrect inflection (assuming that each morphological rule is learned and stored separately). 4. The optional infinitive hypothesis [94, 951. In GD grammars, infinitives optionally take the place of inflected verbal forms. Even if we changed ‘optionally’ to ‘obligatorily’, this hypothesis would suffer problems. Just as the missing features hypothesis is too broad, this hypothesis is too narrow. As (a-n) illustrate, many deficits are observed in GD that do not involve verbal morphology at all, yet plausibly have the same basis as a lack of verbal morphology. This hypothesis also runs up against the problem, noted by Crag0 and Allen [76], that it fails to explain dysphasia in Inuktitut - in this language there is no infinitive verbal form to begin with. 5. The feature checking deficit hypothesis [88]. In GD grammars, there is a general lack of checking for morphological features. In a sense, this is a variant of 2 above, cast in the vocabulary of the Minimalist Program. ‘Feature checking’ subsumes most, if not all, processes responsible for inflectional morphology. In most versions of the Program, this includes both inherent features, such as tense, and agreement features, such as that between subjects and auxiliaries. A potential problem is the fact that as the Program has developed, more and more grammatical properties have been attributed in part to the checking mechanism, including, for example, the basic word order of the language. Yet, as far as I am aware, no dysphasics have trouble mastering the fact that the basic word order of English is SVO, that of Japanese SOV, and so on.13 To summarize, no proposal to date seems adequate to capturing the grammatical nature of the deficit observed in GD, even with respect to the dysphasics’ difficulties with inflectional morphology. But one hopes - indeed, assumes - that as the totality of the problems suffered in GD are covered by increasingly improved descriptive generalizations and that as theories of grammar deepen, more progress will be made in this regard. 5.3. GD and SLI It is important to stress that not every case of SLI is necessarily a case of GD. Deficits reported in many cases of SLI differ sharply from those reported for the speakers of the four languages who seem clearly to have a genetic impairment. For example, van der Lely and Harris [99] describe 14 English-speaking SLI children who have serious difficulties with word order. The more a sentence deviates from canonical word order, the more problems they have in comprehending it. In other words, they appear to be unable to deduce thematic roles from syntactic functions. Nothing analogous has been reported for impaired members of the KE family. Along the same lines, Leonard et al. [ 1001 report a much less diminished capacity to control inflectional morphology among Italian SLI children than has been reported for the four languages in which GD is established. Differences in observed language impairments have led in some cases to differences in the analysis of the underlying grammatical deficit. For example, Clahsen and Hanson [98] and Clahsen [ 1011 discuss a group of German children with SLI who have difficulties with person and number agreement, but who manifest no problems with inflectional morphology in general (e.g. they get participle inflection right). On this basis, they speculate that the children’s grammars are lacking the Control Agreement Principle of Generalized Phrase Structure Grammar [ 1021. But studies of GD-affected families do indicate a general deficit with inflection

Genetic dysphasia

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(including participle inflection), so we cannot automatically equate the German children’s deficits with the grammatical deficit known to be genetic (though it is certainly possible that the German children have a different genetic deficit).14 To cite another example, Rice [103] investigated English-speaking SLI children who made rampant errors with numerical quantifier - noun sequences (e.g. four book), but no more errors than the general population with determiner - noun sequences (e.g. that book). They analyzed such children to have a loss of Spec-Head agreement, but a preserved Head-Head Agreement ([SS]). But in clear cases of GD, determiner - noun agreement is affected. Thus any conclusion that the grammatical deficit manifested by Rice’s children and the deficit manifested in the GD families are identical seems premature. At the present time, we simply do not know the range of possible grammatical deficits, nor whether deeper investigation will lead to convergent analysis, nor the extent of genetic transmission of SLI. l5 One possibility is that the seeming multiplicity of SLI syndromes will turn out to be a function of misanalyses. For example, perhaps Italian-speaking SLI children do better on inflectional morphology than English-speaking children because of the relative importance of such morphology to that language.i6 The former, then, would be more likely to store the correct forms in declarative memory. If so, then their deficits might well be the same as those manifested, for example, by members of the KE family. Such an explanation, however, is challenged by the fact that the Inuktitut SLI child does terribly on inflection, despite the inflection-rich character of that language. Along the same lines, it is possible that the superficially correct participles produced by Clahsen’s children and the superficially correct determiner - noun sequences produced by Rice’s are memorized forms. The published accounts, unfortunately, give us no way of deciding whether this is, indeed, the case. One anticipates the more widespread use of subtle testing procedures to distinguish what dysphasic subjects get right because of their grammatical competence from what they get right because of the elements that they have stored in declarative memory.

6. FURTHER 6.1. GD and the hybrid model of injectional

ISSUES

morphology

Approaches to inflectional morphology have differed wildly within generative grammar, from morpheme-based to word-based, from lexical to rule-driven, from those positing a distinct morphological component to those in which morphology is ‘distributed’ among a variety of components, and so on. Yet virtually all models have taken it for granted that all inflectional processes are, ultimately, UG-based processes in the sense that the innate grammatical principles provided by UG govern their applicability. So consider how the distinction between regular morphology (ask-asked) and irregular morphology (swing-swung) has been handled in various models. The theory of Lexical Phonology ([ 104, 1051) provides an entirely rule-based characterization of the difference - regulars and irregulars are simply handled in different lexical strata. At the other extreme [ 1061, all forms are listed in the lexicon as single units, with redundancy rules of greater or lesser generality relating them. Many have taken a position intermediate between the two. But no generativist, until a few years ago, questioned that they were to be handled in terms of the same system of grammatical competence. In recent years, Steven Pinker and his co-workers have challenged this conception (see especially [107-1091). In their approach, regular forms are, indeed, derived by a generative

F. J. Newmeyer

66

rule. But the irregular forms are outside the system of grammatical competence Rather, they are stored in an associative memory structure with connectionist-like [110, 1111:

altogether. properties

Thus while string and strung are represented as separate, linked words, the mental representation of the pair overlaps in part with similar forms like shrink and bring, so that the learning of shrunk is rendered easier given a constant number of learning trials, and analogies like bmng occur with nonzero probability as the result of noise or decay in the parts of the representation that code the identity of the lexical entry. ([109]: 233)

Pinker and Prince go on to note that “if regular and irregular patterns are computed by different kinds of neural systems, we should expect them to dissociate in individual people impaired in specific ways: certain kinds of populations should evince the ability to produce irregulars but no regulars, or vice-versa” (p. 242). And this is exactly what we find with genetic dysphasics [55, 58, 93, 1121. They perform far better with irregular verbs than with regular verbs, the latter which they learn on a one-at-a-time basis. These show marked frequency effects - verbs commonly used in the past tense are easiest for the dysphasics to memorize, while they never manage to inflect a nonsense word correctly. The most compelling evidence that for these individuals stems and affixes are stored in associative networks defined by the feature [strident] in final position and related by analogy, rather than by rule, comes from their errors: sibilant-final real words sometimes substitute for the plurals of phonetically similar nonsense words, e.g. bronze for [brhm-z]; sibilants other than [s, z] are provided as plurals, e.g. [bus-s] for bushes; and sibilant-final real words are often not overtly pluralized, e.g. [roz] for roses’. ([112]: 37)

In other words, the connectionist models individuals represent cognitive systems memory in the latter

affected individuals deal with inflectional morphology in the way that predict that normals should deal with it. This fact suggests that normal regular and irregular inflectional morphology by means of quite different a rule-based system in the former case and a system of associative case.i7

6.2. GD and the phylogenesis

of grammar

While we are a long way from understanding what gene or combination of genes is implicated in GD, it seems pointless to appeal directly to natural selection for an explanation of why the genome came to incorporate them. Nobody would be so foolhardy as to argue that the first individual with the genetically-provided wherewithal to represent and process inflectional morphology was better equipped to survive to adulthood and to reproduce than his or her unmutated neighbor. Nor (as the KE family attests) does the loss of this ability appear to impact negatively one’s survival and reproductive ability. Indeed, in a number of languages spoken today (Vietnamese, for example), we find neither inflectional morphology nor agreement, yet the speakers of such languages manage to survive and reproduce without undue difficulty.18 But neither is the gene implicated in GD likely to have arisen according to the evolutionary scenario suggested by Chomsky in various books. In 1975, he raised the possibility that the evolution of UG might be attributed to a solution to what is, essentially, a ‘packing problem’, rather than to natural selection: We know very little about what happens when 10” neurons are crammed into something the size of a basketball, with further conditions imposed by the specific manner in which this system developed over time. It would be a serious error to suppose that all properties, or the interesting properties of the structures that evolved, can be ‘explained’ in terms of natural selection. ([116]: 59)

And more recently:

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Evolutionary theory is informative about many things, but it has little to say, as of now, of questions of [language evolution]. The answers may well not lie so much in the theory of natural selection as in molecular biology, in the study of what kinds of physical systems can develop under the conditions of life on earth and why, ultimately because of physical principles. It may bc that at some remote period a mutation took place that gave rise to the property of discrete infinity, perhaps for reasons that have to do with the biology of cells, to be explained in terms of the property of physical mechanisms, now unknown. ([117]: 167-170) Perhaps these [properties of language] are simply emergent physical properties of a brain that reaches a certain level of complexity under the specific conditions of human evolution. ([ 1181: 50)

Lightfoot [119] elaborates on Chomsky’s remarks by suggesting that key properties of language might have been determined by general constraints on the physical form of complex systems, such as those discussed so eloquently by D’Arcy Thompson [ 1201. Piattelli-Palmarini [121] agrees, arguing that UG is a “spandrel” [122], in other words a trait that has arisen as a necessary structural, physical or architectural consequence of some pre-existing trait. In their original and literal sense, spandrels are the triangular spaces formed by the intersection of two rounded arches at right angles, say, in the design of a cathedral. Nobody can deny that such spaces are ‘functional’, in the sense that some of the most magnificent art of the Western world adorns them. But, crucially, they are physically derivative of the arches. Two arches side-byside yield a spandrel. Analogously, in the opinion of Chomsky, Lightfoot and PiattelliPalmarini, enough neurons side-by-side in the pre-human brain yielded UG. I find a Thompsonian/spandrel explanation for the design features of any significant aspect of the language faculty to be utterly implausible, and, for that aspect manifested in GD, to border on the absurd. As a general point, perhaps the most salient (and, at times, frustrating) aspect of UG is its lack of symmetry, the irregularity and idiosyncrasy that it tolerates, the widely different principles of organization of its various subcomponents and consequent wide variety of linking rules relating them. And more specifically, the hexagonal cell aggregates, the equiangular spirals, and so on found repeatedly in nature, and determined by the same laws of physics that suggest the optimal design for a bridge or the arrangement of packing crates have no counterpart in the set of grammatical factors affected by GD. At the present time an adaptationist explanation and a spandrel-based explanation for why the genome came to incorporate these factors seem equally implausible. We therefore have no alternative but to regard their phylogenesis as an unsolved mystery. 6.3. Adult second-language

acquisition

and GD

One question that has been subject to vigorous debate in recent years among generative linguists is whether UG is active in the acquisition of a second language by adult speakers. The community is split down the middle on this question, with some taking the position that the adult second-language learner has full access to UG ([123-1251) some positing partial access [126-1281, and some no access at all [129-1311. Given the notorious difficulty that most adults have in acquiring a second language (contrasted with the effortlessness of children in this task), it is worth asking why one would even raise the possibility that second-language acquisition could be shaped by UG. Wouldn’t an obvious explanation for the difficulty be the absence of a UG to guide learners in this task? Flynn, et al. [125], however, presents a number of empirical arguments that they take as showing that UG is fully active in second-language acquisition. Many of them are based on the idea that adult learners have arrived at different ‘parameter settings’ from those of their native language - settings, they postulate, that could only have been provided by UG. The problem is

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that such arguments tend to assume in advance what they set out to prove. Suppose, say, that in the course of my studying Japanese, I come to learn that the language is verb-final. Is that evidence that UG reset the appropriate parameter for me? The answer can be ‘yes’ only if the grammar of my adult-acquired Japanese is, in fact, a competence grammar in the same sense that my English grammar is. If it isn’t, then some other cognitive faculty steered me toward that knowledge. But the crucial (albeit difficult) task of showing that my knowledge representation of Japanese is identical in relevant respects to that of my knowledge representation of English remains to be demonstrated. The most interesting sorts of arguments for UG driving second-language acquisition are modeled on the poverty of the stimulus arguments for an innate UG itself. For example, Finer and Broselow [ 1321 found that Korean learners of English postulated binding domains for English anaphors that were neither those of Korean, nor those of English. Rather, they appeared to be the domains that UG (as it was understood at the time) took to be the most unmarked. The problem is that experiments testing adult learners with respect to UG principles have led to mixed results. Clahsen [131], for example, has shown that late learners of English accept Subjacency violations. Such should not be the case if UG is shaping their acquisition of the language. So, then, how might GD bear on the issue of second-language acquisition? A number of investigators of GD have observed that the behavior of adult dysphasics in attempting to cope with grammatical features not provided by their UG parallels that of adults struggling with a second language [83, 112, 1341. For example: they speak slowly (half as fast as normals), they have difficulty understanding utterances spoken to them at the normal rate of speech (they typically ask their interlocutor to slow down and/or repeat), and they show evidence of consciously monitoring their speech when they perform. They behave in many ways like speakers of a foreign language which has been formally learned in school and which has not been pmctised. ([83]): 142)

[A]s dysphasic individuals get older, they develop more sophisticated compensatory strategies for coping with their impairment, strategies such as reliably applying the explicitly learned rule ‘add an s’. In this way, they can more readily be compared to many second-language learners who learn rules explicitly, make errors under stress, and although with time can achieve high levels of proficiency, never become native-speaker like ([112]:24). Given the hypothesis that what distinguishes genetic dysphasics from the general population is a UG-deficiency and the observation that such individuals behave, in relevant respects, like normal adult secondlanguage learners, one might draw the inference that the latter also lack the benefit of a UG facilitating their acquisition task. The inference is not airtight, obviously, but the parallels in effect suggest plausible parallels in cause.

7. CONCLUSION The existence of genetic dysphasias, that is, of specific language impairments with a demonstrable genetic basis, provides dramatic confirmation of the controversial hypothesis that humans are innately endowed with a set of universal grammatical principles. At the present time, we are not in a position to characterize the precise grammatical nature of the impairment, nor to draw conclusions about grammatical theory from the errors that are observed in the speech of GD subjects. As studies of GD broaden and deepen, however, we can look forward to the increasing importance of the results of grammatical theory for an analysis of dysphasic speech and an increasing relevance of findings about dysphasic speech for the formulation of grammatical theory.

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theory

NOTES ’ The Subjacency constraint ([7]) prevents a w/r-phrase from being extracted from a noun phrase whose head is itself a noun phrase, that is a noun phrase like rNprNp the claim rs that John saw _l]]. ’ The following argument applies only to those dialects that distinguish between who and whom. 3 More recently, the effects have been derived from different properties of wh- and NP traces ([12]) or from the postulation of a distinct level of ‘NP-Structure’ ([13]). Since both of these approaches mimic the rule ordering analysis in crucial ways, for the purposes of this discussion the simplest expository course is to present the rule ordering analysis. 4 Pinker [48]: 3 15 provides an interesting argument why the language faculty is not confined to one area of the brain. He notes that hips and hearts as ‘organs that move stuff around in the physical world’ have to have cohesive shapes. But the brain, as ‘an organ of computation’, needs only connectivity of neural microcircuitry to perform its specific tasks - there is no reasons that evolution would have favored each task being confined to one specific center. ’ Grodzinsky [49, 501 has proposed a theory of the grammatical basis of agrammatism that does posit a syntax-internal deficit: in his model, the only possible syntactic deficit is the loss of trace in theta position. He applies this conception in later work ([51]) to an explanation of why agrammatic aphasics fail to comprehend properly verbal passives and structures involving wh-movement, hut have no corresponding difficulty with (uncontroversially) lexical passives. But Bickerton ([52]: 78-83) subjects Grodzinsky’s work to careful scrutiny and finds serious problems with its experimental design and some unwarranted assumptions that it makes. 6 The first work to suggest that SLI might result from a disorder of the autonomous grammatical system was [53]. ’ Fletcher and Ingham ([54]: 620), for example, bemoan “the absence of a clear etiology, and the consequent lack of clear identificatory criteria, plus the confounding influences of development and remediation in older subject groups, [which] virtually guarantee extensive variation in any sample selected for research purposes”. s [60] is perhaps the most accessible publication that attempts to attribute the KE family members’ dysphasia to nongrammatical factors. A telling criticism of this publication is that it ignores all work done by Myma Gopnik and her associates that has appeared after 1991. As a consequence, it ignores the bulk of the facts upon which the hypotheses of the Gopnik group have been based. For discussion of the Vargha-Khadem et al. paper, see [61]. 9 [72] suggests that the seeming articulatory deficit is in reality a deficit in the prosodic rules of English that govern the formation of multisyllabic words. lo Which is not to say that there is agreement on the theoretical interpretation of these abilities (see Section 5 below). ” Also, we cannot ignore the logical possibility that what is grammatically a unified phenomenon might not be a genetically unified phenomenon. That is, GD might result from the malfunctioning of several distinct genes, the cumulative effect of which is to give the illusion that a single grammatical principle has been disrupted. Given our present state of knowledge, it is impossible to test for such a possibility. ” Ullman and Gopnik [88], citing [89,90] and other works, suggest that the same general feature-checking mechanism is implicated in derivational morphology as in inflectional, thereby explaining their English subjects’ difficulties with the former. Such a view of derivational morphology is extremely controversial, even among those taking a principlesand-parameters approach. I3 [9698] report that German SLI children do have problems with word order. Clahsen attributes this fact to the intimate connection between word order and agreement in that language. I4 A logical possibility is that whatever UG principle is responsible for inflection loss in GD (for some reason) spares German participles, by virtue of the fact that their formation is the result of a different system from that forming participles in English. If that were the case, then the German deficit would fall in with those reported for English, Japanese, etc. I find this possibility rather remote, however. ‘s [54] notes that in the population of SLI at large, three times as many males as females are affected, while in the KE family the ratio is about 50-50. This fact indirectly suggests that many reported SLI cases are not genetically transmitted, which, in mm, indirectly suggests that there might be grammatically distinct deficits. I6 Leonard [62] suggested (and then rejected) the possibility that the Italian children’s better performance resulted from their having the unmarked setting for the Null Subject parameter (see Section 5.2). ” Further external evidence supporting the same conclusion comes from studies of child language ([113]), aphasic speech ([ 114]), and Alzheimer’s and Parkinson’s disease ([115]). ‘* One hopes that GD researchers will soon turn to such languages. If GD is not attested among their speakers, then the grammatical principles responsible for inflectional morphology would be implicated as being central to this syndrome. Furthermore, if GD manifests itself by the loss of some other grammatical construct, that might provide evidence for a grammatical and/or genetic linking of inflection with that construct.

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