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Lightfoot, David . The Development of Language: Acquisition, Change, and Evolution. Malden, Mass: Blackwell, 1999.
Reviewed by Ron Bonham, Malaspina University-College
David Lightfoot's new study of language acquisition and change, based on a "scientific approach to history," is a challenging work which extends some theoretical notions about language while debunking and discrediting others. It is interesting to see Lightfoot, in his concluding chapter, referring to "we linguistic historians," where the first impression established in this work is that he is far from sympathetic to, or in agreement with, historical principles. Lightfoot is, however, challenging not the historical but the "historicist" approach to language and, in fact, to knowledge in general, offering in place of Newtonian-style theories a "chaotic" view of language development based on his notions of "catastrophe" and "cue" with some significant grounding in UG and syntactic study. A book which offers a "biological view of grammar," rather than a social one, The Development of Language is a complex and even perilous Odyssey (to use Lightfoot's own metaphor), at times perceptive, controversial, and engaging, at times clunky, overly abstract, and forbidding.
In light of the work of Chomsky, perhaps Lenneberg (although curiously not mentioned here), and more recent work by such linguists as Kroch, Niyogi and Berwick, Lightfoot presents a vigorous, sometimes heady study of language acquisition with some valuable insights into the child's active, creative role in language development which could be applied to an understanding of how the ever-illusive, controversial LAD may operate. It is difficult to know, however, what sort of readership the author has in mind as, at times, he explains fundamental concepts like notions of language genealogy and the distinctions between language and grammar, yet offers a limited understanding of literacy with no recognition of discourse issues, presents a simplistic review of language origins theories, and then offers advanced studies of issues like genotypical systems, maladaptiveness, nonlocal antecedents (indexed), etc. Granted, Lightfoot has shaded passages written for what he calls "dedicated linguists" which he considers optional; however, these passages are not always the most difficult parts of the presentation and are not really independent of the unshaded text. It is true, as the author claims, that the "central ideas" can be grasped with little background by "those who have thought little about language," but much of how those ideas are arrived at otherwise lacks transparency. Discussions of complex parameter settings, employment of X-theory, V to I raising, and the implications of Government Bindings, Blocking Effect and Subjacency Conditions are clearly inaccessible to readers who have previously read only the required "introductory text" without a comfortable grasp of syntactic and acquisition theory. The style of the opening and concluding chapters is also directed more to the reader with discursive commentary and even humor, while the central chapters read more like academic papers not fully digested into the overall text.
Synopsis/ Structural Analysis
The first three (of a total of ten) chapters in the book establish the context for Lightfoot's examination of language change, in particular "the structural changes which have affected the grammars of English speakers" (19). Examining the impact of nineteenth-century linguistic thought, the views of the "century of history," the author finds himself focussing on two main "beefs" with its highly influential perspective: it is "too deterministic" and offers a limited "incomplete view of language". In fact, the discoveries of patterns of correspondence in the 19th century influencing and influenced by historical-evolutionary understandings, led to the general view that languages were underpinned by predictable laws which could show them shaped in "systematic" ways. This viewpoint leads to an advocacy of a "gradualist" perspective on change with much greater focus on product than on process. The emphasis of the 19th century was, thus, on a drive to establish directional change through focus on complex word elements and an undefined, incoherent sense of "language".
In light of the advances made by Chomsky and the rationalists, Lightfoot argues that the emphasis on biological grammar, "which is represented in the mind/brain of an individual," challenges the 19th century perspective. The review of the rationalist objections to imitation theory, reinforcement and the genetic explanation for language acquisition - especially in dealing with "poverty of stimulus" - is rewarding and informative and pursues a somewhat persuasive model of grammar which is scientific and "uniquely computational". Drawing on notions of internal grammar and trigger experiences (in contrast with input models), Lightfoot employs the notions of molecular biology to argue for the individual development in children of a "system, a grammar, which at certain stages of development yields things which no child hears from English-speaking adults". While such a viewpoint is convincing in emphasizing the creative aspect of language development, Lightfoot's work is more convincing with syntactic structures than it would be in areas like accent, register, and semanticity which, in fact, receive minimal if any consideration here. In fact, the author is preparing the ground for a challenge to the existence of a social grammar, a point which seems pushed too far in an attempt to emphasize the pervasive impact of the biological grammar on language change.
Chapters 4 through 7 present the heart of Lightfoot's book. In Chapter 4, "Gradualism and Catastrophes," he offers the reader the contrast between the viewpoint that languages change in a slow, continuous manner - the view which "has pretty much had hegemony" (83) and the view that languages change in abrupt and discontinuous ways. The latter view, which the author relates to "catastrophe theory," he calls "catastrophic" (emphasizing the calmer French sense of the word in chaos theory)) where shifts and "bumpy discrepancies" are evident and where the focus is not on "social entity" but on "individual mental entity" as the understanding of the nature of grammar. This chapter offers some interesting, persuasive evidence of the features of language change (new phenomena clusters, chain reactions, S curve spread, impact of obsolescence, meaning change, new grammatical properties) and an important reminder about the complexities of sets of grammars and coexisting grammars as opposed to the notion of a single, monolithic grammar. It is here that Lightfoot dismisses the notion of "social grammar," however, where he ties meaning change to structural change without realizing the value of lexical change independent of lexicalist models which he sees as too "data-driven".
Lightfoot calls Chapters 5 through 7 the "analytical core" of his book. Here he does some in-depth study of specific instances of "catastrophic" changes where he shows their considerable impact. Drawing upon the notions of thematic roles, the Minimalist Program, case analysis, he arrives at some convincing evidence for the catastrophic viewpoint and his lead-in to how language change takes place. It is here where he introduces his notion of a "cue-based acquisition". Lightfoot points out that the common-sense view of diachronic change - as the result of major disruptions due to the external influence of population movement/ dispersal - is based on some false assumptions in the construction of learnability models. These include the deterministic-evolutionary notion of survival of the "fittest grammar" and the false notion of input-matching which he has already countered with the "poverty of stimulus" evidence and here by the further problem of succeeding with negative and degenerate data.
At this point, the author introduces "cues" or "designated structures" which are found not universally but only in certain grammars and which define the parameters of and between grammars. Lightfoot's definition of cues is necessarily vague at this point - "intensional elements, grammar fragments". These cues act as structural triggers and reveal the interconnected nature of morphology and syntax. Later in the book, the author admits that it is still far from clear why cues must be followed. UG does not really help here, since it always permits a range of optionality. Hence some of the actual "psychology" of cue-based acquisition remains uncertain. Nonetheless, Lightfoot's analysis of grammatical examples here and in the subsequent chapter are persuasive evidence that such changes are contingent and yet "deterministic" in that they are abrupt and the impact unpredictable while parameter settings cannot be undone once in place and a set "learning path" established. Without some "theory of cues," which does not exist, and lacking any "fitness measure," this examination shows the reader important ways of analyzing language change on 2 levels (the UG level where changes are unified and the more contingent although not entirely random account of why change occurred) but not a clear sense of what the parameters really are or how to define or identify a possible cue.
The final 3 chapters of this book (8 through 10) widen the focus of the argument to look at "big ideas" (19) and implications of the approach to language change. In some ways, Chapter 8 balances with the discussion of the nineteenth century view of language change presented in Chapter 2. Here Lightfoot reveals the essence of his skepticism about historicism and his view of historical law as epiphenomenal. Basing his conclusions on the central argument he presents for catastrophic change and cue-based acquisition, he convincingly argues for a balanced perspective of interaction between chance (shifts in the distribution of cues) and necessity (biological reality). Such a viewpoint allows for the influence of factors that are not grammatical and for acknowledgement of the chaotic and unpredictable. Lightfoot argues convincingly that UG properties are invented by historicists based on assumptions about the nature of language only to explain issues of directionality (as in discussion of Bauer's work), although the research of Niyogi and Berwick, largely supported here, includes the notion of "richer" inflectional systems which is, in itself, an implicit judgment about how languages develop.
Chapter 9, "The Evolution of the Language Faculty," presents some solid critique of the perspective of evolutionary theory, which have had enormous impact on the traditional view of language change. Lightfoot contrasts the "singularist" perspective , which emphasizes natural selection as the sole factor governing the changes, with a "pluralist" one where natural selection plays at best a limited role and where other non-predictable factors pertain. This viewpoint challenges the "Panglossian fallacy" (that "anything that performs a function well must have been selected for that purpose") of the singularist by demonstrating the significance of "spandrels" as by-products, the impact of physical principles, and the presence of maladaptiveness in language change. Although Lightfoot points out the lack of empirical evidence, he argues that physical laws are as likely a factor in change as environmental ones since environmental factors do not "suffice to shape the changes that result" (251).
The discussion of the limits of the evolutionary perspective leads to the final chapter -- an exhilarating read - where the author makes important distinctions between randomness and predictability. Here he reinforces his cue-based approach, showing that language change "is not random, but is unpredictably a function of contingent changes in the distribution of cues" (259). The concluding examination of the "interplay of chance and necessity" leads to confronting the current limits in theorizing about language change. Thus, without a coherent theory, reconstructions can reveal similarities but cannot hypothesize about the unattested. Grammatical changes result from "exposure to a new triggering experience," but we are unsure of how scanning for cues really takes place or what number of cues is necessarily involved and the potential impact of epigenetic development. Also, the impact of "neurological limits" in language development is still undefined, uncertain. Nonetheless, Lightfoot argues that the historians of language are in the best position to develop a model of change theory with some limited predictive capacities - and perhaps the predictiveness can be advanced further if chance is not overlooked in defining the "range of available options for the new grammar".
The approach to language change becomes particularly heady stuff as this point - an interesting challenge to the traditional ways of examining universal change along law-governed evolutionary lines. Certainly more understanding of neurolinguistic data would help with further theorizing about a cue-based acquisition approach . Lightfoot's book merits some caveats about exploration of too many scientific analogies and principles - DNA, genotype/ phenotype of molecular biology, chaos and catastrophe theory, motion theories, etc. - in order to establish empirical grounding for the uncertainty of his claims. At times, the over-detailed examination of some elements where the author seems impressed by his own erudition (eg. scaling laws, historical approaches, heavy analysis of V to I raising) clouds the central focus. The unevenness of the chapters - where the central, unfortunately rather arid ones sound more like isolated academic papers than integrated parts of the book - weakens the overall presentation. However, this work presents some important advances on notions of language acquisition and change; it also consolidates challenging ideas on the interplay of language development which can only deepen understanding of this complex reality. Lightfoot calls on linguists, scholars, and all interested parties to see the potential for thinking in new ways and furthering research, thereby significantly affecting how our world looks at and understands change.
R. A. Bonham
Malaspina University-College, Nanaimo, BC. Canada
(R.A.Bonham is a Senior Faculty member at Malaspina U-C where he teaches Linguistics and English and coordinates the Writing Center. His interests include Indo-European philology, History of Writing Systems, Stylistics, and Literacy, and he has devised new curriculum and supervised upper level projects in these areas.)