Innateness and Maturation
Linguistic Development
KENNETH WEXLER
Department of Brain and Cognitive Science
Department of Linguistics and Philosophy
Massachusetts Institute of Technology
Cambridge, Massachusetts
Language is species-specific, species-wide, and highly structured. Its principles (Universal Grammar) are innate (genetically determined) in the child, although some linguistic capacity is subject to a
maturational schedule, examples of which are given. Some particular aspects of language are learned,
in a way driven by Universal Grammar. However, empiricist "learning theories" of all types are far
too weak to be useful in explaining either the final adult language or the precise timing of developmental
processes. The assumption of Universal Grammar is, in fact, crucial in explaining what kind of learning
actually takes place.
Imagine a symposium on "The Idea of Innateness: Effects on Research on
Physical Development." And consider some of the questions that one might ask,
questions that parallel the questions asked in our symposium. What are the advantages and disadvantages incurred if a theory of physical growth assumes that some
aspect of this growth is innate? Do we incur, in assuming innateness, logical
problems in our explanation of the origin of physical structure of organisms because
defining a structure as innate entails accepting the null hypothesis that learning
and experience have no effect? Do we direct our attention away from measuring
and theorizing about the environments of children developing adult bodies, and
do we consequently lack a coherent and general theory of the environment in
which children develop their bodies?
To pursue the analogy in this way is to demonstrate the odd ring of the
questions. To my mind, the questions are just as odd in the domain of language as
they are in the domain of physical growth. After all, it is quite possible to create
theories of physical growth that depend on learning rather than on innateness.
Consider, for simplicity, theories of how children might learn to grow. Basically the idea is that something in their environment causes them to grow. They
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Reprint requests should be sent to Kenneth Wexler, E10-020, MIT, Cambridge, MA 02139
Received for publication 1 February 1990
Revised for publication 18 June 1990
Accepted at Wiley 25 July 1990
I
Developmental Psychobiology 23(3):645-660 (1990)
0 1990 by John Wiley & Sons, Inc.
CCC 0012-1630/90/070615-16$04.00
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start out as quite short and learn to become much taller. The familiar range of
learning theories will apply. Thus perhaps we should believe that children learn to
become tall by reinforcement. Each time a child grows just a little bit, a parent
will positively reinforce the child. The familiar range of positive reinforcers will
be available-from M & Ms to smiles and encouragement. And negative reinforcers too: The child's growing taller will release her from all the difficulties
related to shortness, for example, being unable to reach the peanut butter. The
child might make a mistake and actually become shorter. In that case, some
theorists will say, it might be effective for the parent to punish the child.
On the other hand, there might be a school of nonbehaviorist psychologists
who believe that reinforcement plays a quite small role in learning to become tall.
These psychologists believe that the child "models" the behavior of the adult,
essentially learning to imitate the adult in height. Thus, by seeing tall adults and
older children, the young child gradually approaches these in height.
There might even be a more sophisticated, "cognitively" oriented psychological theorist. Such a scientist would say that the child's "construction" of height
was a much more complex business than mere imitation. The child would construct
a theory about how tall he or she should be, how fast to grow, etcetera. This would
be done as some kind of complex calculation on observations of others' heights.
Of course, even this cognitive psychologist would not have appreciated all the
potentialities that a child has in constructing height. Many more factors and
capabilities are to be seen in a child's growth. In particular, the child will construct
his or her height in a complex interactive way with the social environment. The
child will have to determine how tall to become, how fast to grow, etcetera, in a
way that makes sense out of the social environment. The child will have to do
what is "expected." Sociological processes of all kinds will enter in.
I could continue, perhaps even bring a deconstructionist view to the issue of
a child's growth. The point, of course, is that all these speculations would strike
any reader as absurd. Probably the deepest question on the topic of this symposium
on the idea of innateness in language acquisition studies is the question not asked:
Namely, why doesn't the idea of "learning" as the major basis for the child's
linguistic growth strike the ordinary person with the same sense of the bizarre as
does the idea of learning as the major basis for physical growth? This is a question
I can only speculate on, and it is a diMicult question indeed. Note that it will not
do to suggest that the fact that people learn different'languages justifies the belief
that the entire basis for language development is learning. After all, there are
definite effects of experience (e.g., nutrition) on physical growth, but everybody
accepts that physical growth is essentially guided by a biological program.
I will answer the questions put forth for this symposium, but I would ask the
reader to bear in mind that I consider the questions to miss the point in the same
way that the reader would consider the analogous questions for physical growth
to miss the point. I hope that my answers to these questions might contribute
in some small way to the reader's feelings that the questions are not the right
questions.
First, I will sketch in the broadest outline the view of languge acquisition that
underlies my work in this field. Much of this view I share with a small community
of researchers in language acquisition who acknowledge the central role played by
linguistic theory. Where there are differences, I will try to point them out.
1
INNATENESS AND MATURATION
647
To begin, the child is born with implicit (generally unconscious) knowledge of
the principles of language.' The totality of this set of principles is called Universal
Grammar (UG; Chomsky 1965, 1981, 1986; for textbook introductions, see Lasnik
and Uriagerekka 1988; van Riemsdijk and Williams 1986). UG determines the
basic structure of all possible languages. Since the child is biologically given
UG-that is, she obtains UG as a matter of genetic inheritance-we can say that
the principles of UG are "innate."
when we say that UG determines all possible languages, of course, we mean
"biologically possible" languages. One can invent all sorts of systems and call
them "language," but systems that do not conform to UG will never be natural
languages. Only systems that conform to principles of UG can develop in the child
in a natural way. This kind of distinction is well known within biology. Humans
use cameras, yet we say that the eye is genetically determined, whereas cameras
and other photographic devices are not.
UG contains principles governing the formal structures and interpretations of
languages. For example, principles of UG will tell us why Sentence 1 is a fine
sentence, whereas Sentence 2 is distinctly odd, much worse than Sentence 3
(* means "odd"):
(1) John laughed at himself.
(2) *John's sister laughed at himself.
(3) John's sister laughed at him.
Basically the structural relations between antecedent and himself are different in
Sentences 1 and 2, and principles of UG govern these structural relations.
The hypothesis that there is a UG and that it is innate entails that all natural
human languages conform to UG. A primary problem in linguistic theory is the
study of the nature of UG and the empirical testing of the world's languages with
respect to it. Needless to say, this is a complex problem, with new data and
analyses arising often. Nevertheless, one result seems clear: There is a UG.
Languages of the world, despite superficial differences, share a striking fundamental similarity, and this essential core can be studied and described. The last decade
in particular has seen remarkable progress in the discovery of highly specific,
though abstract, principles that govern all languages.
Although they are highly similar, as instantiations of UG, languages do differ.
Minimally they differ in their lexicons. Possibly they also differ in the values of
"parameters" that are associated with the principles. The idea is that there are a
small number of parameters, each of which has a small number (perhaps only two)
of values: and that the values of these parameters are fixed by experience. To take
an example, one particular application of a more general principle says that verbs
take their objects in a close structural position, which on the surface will show up
immediately before or immediately after the verb. It turns out that some languages
have grammatical objects that follow verbs and some languages have objects that
precede verbs. Whether the object precedes or follows the verb may represent
values of a parameter that has to be learned. (It is clear that the parameter involved
is more general than this.)
Even assuming that there is much in common in human languages, one might
ask why it is hypothesized that UG is innate. Why isn't it assumed that the principle
of grammar are "learned"? Again, there is a large literature on this topic, both in
linguistic theory and in learnability theory. It can be shown that the principles of
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language are such that there is no learning procedure capable of learning them
when the procedure itself is initially uninformed about the character of the principles (Wexler and Culicover, 1980).2The literature shows in a detailed and rigorous
way the impossibility of learning-theory solutions to acquisition puzzles, and there
is no literature that shows how learning theory can solve acquisition puzzles of a
real kind-namely, how actual linguistic structures can be learned.
Consider, for example, one well-known approach. Slobin (1973) hypothesizes
a set of "operating principles," which the child uses to learn language. The
statement of one such principle might give the flavor of the rest: "Pay attention to
the order of words." These "principles" are so general and vague that they can
hardly be tested. Moreover, they illustrate that learning-theory literature does not
show how acquisition puzzles can be solved. There is no way that the Slobin
operating principles can even begin to be used as a theory to explain how language
develops. See Pinker, 1989, and Wexler and Culicover, 1980, for further discussion
of Slobin's approach. No empiricist approach has mechanisms powerful and precise enough to provide the basis for linguistic development.
Within linguistic theory and acquisition theory based on linguistic theory, the
classic view has been that children are born with the principles of UG. Children's
language, on the surface at least, is quite different from adults' language for a
number of years. Thus the question arises: Why i s the child's language different?
There are many answers to this question, and all of them are true to some
extent. First, it has been shown that children have underlying grammatical knowledge when it casually appeared as if they did not (Hamburger & Crain, 1982).
There are many reasons, including performance and memory limitations, why
children do not speak as adults do even when they have adult knowledge. On a
modular view of cognitive and linguistic abilities (Chomsky, 1975; Nadel and
Wexler, 1984), we would expect behavior to be effected by different modules, and
that one module (e.g., grammar) might be fully present in the child, while another
(e.g., processing abilities) might not be fully present. Second, children do have
some learning to do, at least the lexicon and possibly the setting of parameters.
Until these are done appropriately, children might speak differently.
In recent years, however, an additional reason has been given for why children
might have different grammatical knowledge than adults do, even when the principles are innate. Borer and Wexler (1987) have argued that grammatical capacities,
even though innate, might mature, taking time to unf01d.~The idea of maturation
is that some abilities develop over time instead of being present at birth, but this
development is in essence guided by a biological program and internal mechanisms
rather than through learning from the environment. The maturation envisaged is
maturation of specifically linquistic (grammatical) capacities, not simply general
cognitive or performance abilities, though these might mature as well.
There appears to be stages in the development of language in which certain
nonadult constructions last for months, sometimes longer, even though the evidence (the "triggering data") that the child needs to move on from this stage is
readily available to her.4 For example, Borer and Wexler (1987) argue that the
capacity to form the kind of movement relations underlying passive sentences
such as Sentence 4 and "raising" sentences such as 5 matures and is not available
at the early stages of language development:
INNATENESS AND MATURATION
64
(4) Mary was seen by John
(5) John seems to have left
An example concerning an earlier stage will be given shortly. Learning-basec
explanations have difficulty in saying why the child does not learn.' Borer ant
Wexler (1987) call this the "triggering problem": Namely, why does the child sta:
in a certain stage for months, even though the information needed to move from tha
stage is readily available? Borer and Wexler propose that the child's grammatica
capacities have not matured to the point where she can construct the adult analysi:
of particular linguistic phenomena. Thus the child gives a different analysis, consis
tent with her capacities, to the phenoma.
Following Borer and Wexler, let us call the assumption that specific grammati
cal capacities mature the "maturational hypothesis." Note that the maturationa
hypothesis assumes innateness-there is no way that the capacities involved coulc
be learned. Linguistic development is looked on as an unfolding of linguistic abilitj
in time, guided by an underlying biological program. Linguistic development i:
assumed to be similar to the development of many biological processes that take
time to unfold. (For a discussion of maturation in vision, another cognitive system.
see Held, 1989). The general character of the time course itself is set by the
biological program, although there will still be some effects of experience. Thus,
for example, the general time course and structural characteristics of the development of secondary sexual characteristics is set by the underlying biological program, although a number of environmental factors, for example nutrition, can have
an effect on the time c o u r ~ e . ~
The framework I have sketched, in summary, is that there are innate universal
principles of language (UG), which are biologically determined. In addition, some
learning is necessary, for the lexicon and to set parameters. Some of the capacities
allowed by UG develop over time via maturation. Of course we do not have any
idea yet of the biological mechanism of this maturation, but that does not mean
that the capacities do not mature. For a very long time biology believed that
physical growth was maturational even though it had no understanding or even
hint at the biological mechanism for this growth.
In general, in the language acquisition literature, there are two arguments
for maturation of a specific capacity. First, some construction appears to be
significantly delayed, and there seems to be no way that the abilities underlying
the construction can be learned. Second, the hypothesis that a particular ability is
maturational can make very strong predictions about the development of what
appear to be very different constructions. Suppose that these two constructions
depend to some extent on the same underlying linguistic ability and that this ability
matures. Then we can predict that both of these constructions will be delayed and
that they will appear at the same time. This logic, a classical logic in the argument
for maturation, has been applied to a number of cases in linguistic development
(Borer & Wexler 1987, 1988, 1989; Guilfoyle & Noonan, 1988.)
To take one example, Borer and Wexler (1988,1989) show that a very surprising object-agreement stage in Italian child language correlates with a stage in which
Italian-speaking children cannot use intransitive verbs in the past tense. (The
original data, in Antinucci and Miller, 1975, had resisted convincing explanation.)
I will give an example, translating word for word into English:
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(6) Mary has taken (plural) the books (plural)
(The simple past in Italian is the form with have, and this is the form the children
develop first. Sentence 6 means "Mary stole the books"). The Italian children
systematically mark the verb stolen so as to agree with the object the books. That
is, both the verb and the object are marked plural, although the adult language
does not have this marking. The same children will say transitive sentences such
as Sentence 6 in the past tense, but they will not say intransitive sentences (without
an object) such as 7 in the past tense;
(7) Mary has cried
Italian-speaking children have no problem with intransitives in general, since they
will use them often in the present tense, as in Sentence 8:
(8) Mary cries
The relevant maturational development takes place before two years six
months and both of these rather surprising phenomena disappear at the same age
(to the limit of precision of currently available tools). Borer and Wexler also show
that another surprising stage in the development of English, in which children
often delete the grammatical subject of a sentence (which is grammatical in some
languages, but not in English), follows from the same maturational development.'
For example, the English-speaking child will very often say sentences such as 9,
without a subject:
(9) hit book
Sentence 9 has definite reference to a subject. For example, it means "1 hit the
book" or "Daddy hits the book."The prediction is that English-speaking children
will move out of this surprising "null subject" stage at the same age (between two
years and two years six months) as Italian-speaking children move out of the stage
in which they exhibit the two surprising phenomena 1 have described (obje.ct
agreement and lack of past-tense intransitive); this detailed prediction is confirmed.
The expanding literature based on assumptions of innateness describes and
attempts to explain many developmental phenomena in detail. The hypothesis of
innateness is an extremely useful feature, and that is the core argument for it in
this field; namely, innateness seems to be empirically true. It allows us to integrate
and make sense of a large variety of empirical phenomena that we otherwise cannot
understand at all.
With this extremely brief sketch of the field as background, I would like to
turn to the questions presented to us by the organizers of the symposium. It should
be clear that the questions are phrased from a particular point of view: namely,
from the point of view of what we might be losing by assuming innateness. One
could ask the questions in exactly the opposite fashion: namely, what do we lose
when we do not assume innateness? This would probably.be a much more useful
way of asking the questions, since the overwhelming assumption in psychology
(especially mainstream American psychology) has been that there are no innate
principles of language (especially specifically linguistic innate principles) and that
"learning" is the explanation for language development. The assumption of innate
ness is definitely a minority opinion in psychology, limited in the domain o
language acquisition mostly to those influenced by linguistic theory .8 In some othe
domains of psychology, for example perception, or in biologically in
psychology, the possibility of innateness is quite widely accepted (with the
INNATENESS AND MATURATION
651
tion that there is also sometime plasticity; Held, 1989; Hubel and Livingstone,
1987).
1. What definitions of "innate" have been used or implied by language and
communication researchers, and what meaning of "innate" makes sense in the
context of language acquisition?
The sense of "innate" that is used by language acquisition researchers who
assume innateness is as I have given it. Namely, innate abilities are genetically
determined: they are biologically inherited. As I have discussed, it is an open
question whether all the relevant grammatical abilities (UG) are present at birth
or whether some only develop over time. In either case the relevant linguistic
capacities are taken to be innate.
This usage of "innate" is perfectly coherent and clear and is the accepted
usage in much of biology and in some other areas of psychology (those where much
progress has been made, such as perception). Sometimes people use "innate" to
be mean "present at birth" so as to disallow maturation, but that is not the usage
I am intending.9 Innate means given by inheritance as opposed to being learned
through experience. Of course the assumptiion that some linguistic capacities are
innately given does not preclude the possibility of learning with respect to other
properties of language. And the theories I am discussing all have the property that
some learning takes place, for example, the lexicon, parameters. This is necessary,
since there exists some variation across languages. The fundamental empirical
assumption, of course, is that any normal child can learn any natural language if
placed in an environment where that language is spoken.
2. What are the advantages and disadvantages incurred i f a theory of language
acquisition assumes that some aspect of ability is innate?
The "advantage" is obvious. If an aspects of linguistic ability is indeed innate,
then the assumption that it is innate has the "advantage" of truth. If the ability is
not innate then a theory which assumes its innateness has the "disadvantage" of
falsity. So it all depends on the simple fact of the matter-is the ability innate or
not?
In terms of the development of the field of language acquisition we can say
more. Allowing for the possibility of innateness (of UG) in the study of language
acquisition has led to the investigation of a wide body of empirical material in
linguistic development, material excluded from consideration in the older learningtheoretic accounts. It seems to me that this empirical material was excluded from
consideration because learning theories could not even begin to make sense out
of how it might develop. Thus learning theories concentrate on extremely simple,
rather peripheral aspects of linguistic abilities." Thus an advantage of UG (innateness-based) models of language acquisition is that they allow, in fact have generated, a large number of detailed studies of the development of complex linguistic
phenomena."
A further advantage of UG theory in language acquisition relates to the Italian
example that I discussed previously: we can account in a principled manner for
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the relatedness of developments that would otherwise appear unrelated. Without
the theoretical assumptions, we might not even see that these developments were
related.
Another advantage of UG models, ironically enough, is that they allow for a
much more precise study of "learning" in linguistic development. Since learningtheory based models assumed that everything was learned, and since this assumption does not work, those models could never be very convincing in their attempt
to understand learning. UG models, on the other hand, allow a role for learning
and attempt to determine which aspects of linguistic structure are actually learned
and which are innate.
Let me take an example. Reflexives (such as herselfin English) must have an
antecedent in the sentence in a position structurally determined by innate principles. There may also be some variation in how far away this antecedent can be.
In English the antecedent must be fairly local; in Japanese the antecedent can be
much farther away.I2 In English, Sentence 10 is grammatical, whereas Sentence
11 is odd:
(10) Mary should point to herself
(11) *Mary thinks that John should point to herself
Sentence 11 is much better if the pronoun her replaces the reflexive herself. In
Japanese, however, the equivalents of both Senctences 10 and 1I are grammatical.
In short, the English reflexive demands a local antecedent, whereas the Japanese
reflexive allows a "long-distance" antecedent.
Thus this aspect of locality must be learned by the child. Extensive discussions
of the learning problem in this situation have been carried out.,The general assumption is that the child learns from positive information only, that is, that there is no
environmental information available to the child that tells her that her sentences
are ungrammatical. Parents do not generally correct young children for errors in
the stucture of their sentences. And they certainly do not teach them the principles
of grammar, principles of which they are for the most part unaware. I will discuss
the empirical basis for the "positive evidence only" assumption in my answer to
Question 6.
On the assumption that only positive evidence is available, if the child ever
has a grammar in which locality need not be observed (for example, one in which
she allows both Sentences 10 and l l ) , then there is no way to ever learn locality
(to infer that Sentence 11 is ungrammatical.) Since we know that both Japanese
and English do develop, we assume the Subset Principle-the child will try the
smaller language first; that is, the child will assume that antecedents must be local.
This theoretical prediction concerning learning has been tested, and there is some
evidence that it is true.13
Without the assumption of (innate) principles of Universal Grammar, which
determine the possibilities for antecedents of reflexives, the variation literature
and the learning literature would not have developed. There is no corresponding
study of these issues in a learning-theory setting. The assumption of innateness
allows for a much more finely delineated and specific study of learning itself.
Essentially, the study of parameter-setting is a study of learning-a study that has
not been carried out in a learning-theoretic setting. For other examples, see the
articles in Roeper and Williams, 1987, and many other sources.
r
INNATENESS AND MATURATION
653
One of the more intriguing results of the recent development of UG-based
language acquisition studies is the extent to which it has spawned experimental
studies of children's linguistic knowledge. Pinker, 1989, has pointed out how one
major stream in empiricist language acquisition studies is such that almost no
experimental studies have been taken as relevant. It is the rationalist theories, the
ones that assume innateness, that have generated the experimental studies. This
result appears paradoxical, but it really is not. If empiricist theories are made
precise, their disadvantages-that they provide no explanation of how language
can actually develop, no mechanisms that yield the final state or even most intermediate states-are immediately apparent. The empiricist theories have to be made
vague so that these disadvantages are not so clear. It is difficult for vague theories
to generate experiments to test and refine them. The innateness-based theories,
on the other hand, have generated clear experimental predictions, and a large
number of these experiments have been carried out.
3. How do ideas about innateness shape what is considered as data, and affect
the organization of data in studying communication and language development?
The assumption that linguistic principles are innate leads one to study whether
young children have these principles. Thus we are led to studying complex details
of young children's language. The contemporary literature on UG-based approaches to language acquisition demonstrates how important data concerning
children's language is. In contrast, consider an extreme version of an empiricist,
learning-based explanation of language acquisition. Skinner, 1957, is an attempt
to explain language learning via principles of reinforcement, yet there is almost no
data from children's language. In fact, what reinforcement theorists will concentrate on is usually an artificial example, constructed in accordance with some
aspect of learning theory; for example, the memorization of nonsense syllables or
the learning of an artificial "rule" that has nothing to do with actual language. But
UG-based theorists will want to know the empirical details of actual language
development. Thus the most relevant data for such theorists will involve aspects
of real language and not artificially constructed examples.
Moreover, attention to the actual stage of knowledge that the child finally
achieves (as specified in linguistic theory) has focused on specific kinds of data
and of patterns of data (for example, the Italian data I discussed earlier). There are
large domains of linguistic knowledge that have never been investigated because
traditional empiricist approaches worked from a theory of language too impoverished to contain a place for this knowledge. Only recently, with the advent of
innateness-based theories, has the empirical investigation begun.
Furthermore, as I have indicated, I believe that UG-based theories will have
to be maturational. Linguistic phenomena are tied together by abstract principles;
when certain abilities mature, many different phenomena are predicted to appear
together. To test these theories, precise timings of the appearance of various
constructions will have to be studied. Thus the assumption of maturation will
lead (and has led) to a much more fine-grained view of timing of developmental
phenomena. Traditional non-UG based theories, even when they involve linguistic
phenomena, are often cavalier with respect to the exact timing of the appearance
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Or consider Newport, Gleitman, and Gleitman, 1977, probably the most
methodologically careful study to date of the linguistic environment to children
with respect to the learning of syntax.I6 The conclusion of this study is the
opposite of the claim made by many empiricists that talk to children ("Motherese") has special properties because it is a teaching language, being ideally
suited to "language lessons." Newport, Gleitman, and Gleitman show that this
is not at all the case.
There are many cases where current UG-based theorizing has led to actual
study of the linguistic environment. For example, Hyams (1986) predicted and
confirmed that sentences with pleonastic subjects (such as there in "there is a
book on the table") would not appear in the speech of children in the null subject
stage. To show that this is not an effect of input, Hyams showed that adults do
use there in speech to these children. In short, UG-based language acquisition
studies do not imply that the environment should not be studied; they often give
reasons why it should be studied.
It is important for innateness-based theories of language developmeilt to study
what the effective input is and how it operates in those domains where there is
learning; the lexicon is one. There have been a number of attempts to study
environmental effects within innateness-based theories; for a recent innatenessbased study attempting to pinpoint the source of environmental information for
the learning of verbs, see Gleitman, 1990.
In studying the development of a biological organ (or a metal organ like
language) it would be a mistake to ignore effects of such environmental factors as
nutrition, drugs, the atmosphere, trauma, and malfunctioning of other organs or
cognitive abilities. Each of these is a topic worth investigating. But within biology,
they are studied in a basic framework that assumes that there is a genetically
guided program underlying normal development. l7 For example, we can ask what
nutrition is needed at any stage of development; what, if anything, will lead to
faster or different development; and what the limits are. It is important to know
that malnutrition can severely limit mental development. Such answers might
have large practical importance. But the limits of the effects of nutrition are also
important. A greater number of vitamins is not going to turn one species into
another.
Conclusion
I have tried to outline a conception of linguistic development in which language
is a biological system that develops in time according to a biological program. As
with other biological systems, there are effects of experience on this development.
Some of these effects we call "learning." (In biology the capacity for these effects
is sometimes called plasticity.) There is a body of observational, experimental,
and theoretical research that continues to investigate this conception of language
as a biological system in an attempt to discover its exact properties. We have made
some progress, although much remains to be done. Perhaps the greatest sign of
the vitality of the field is the increasing availability of new and explicit information
about the child's knowledge of specific linguistic structures at particular ages and
of how the knowledge of one piece relates to the knowledge of another. The current
moment is a very active time in the study of the universal principles of language
INNATENESS AND MATURATION
657
development. If a similar symposium were held ten years from now, I would be
surprised and disappointed if the range and depth of our understanding had not
increased considerably.
Notes
'
In linguistic theory and the study of language acquisition, an important distinction is made
between the notion of grammar, the representations and processes in a person's mindlbrain, and
language, a much less well defined notion. I will have to conflate these notions here. See Chomsky,
1986, for extensive discussion.
For many arguments within linguistic theory based on the "argument from the poverty of the
stimulus," see, for example, Chomsky 1975, 1986. For learnability theory within a "standard theory"
linguistic framework, see Wexler and Culicover 1980; Wexler, 1982. For general discussion of this
basic argument from the poverty of the stimulus and its relation to other work in psychology, see
Wexler (in press). The crucial aspect of the argument from the poverty of the stimulus is not that the
stimulus is "poor" or degraded in some way; the basic argument is rather that the child's developed
abilities go way beyond the stimulus-there is no way that the environment can determine the child's
complex developed abilities. This is commonplace in such areas of psychology as the study of perception, and it is the accepted viewpoint in most of biology.
Borer and Wexler (1987, 1988, 1989) present a strict growth theory of maturational development.
Felix (1984) suggests a maturational theory that allows for a much greater variation between child and
adult abilities-essentially, the child might have a system not at all like the adult system. For example,
there might be a "semantic stage" in early child language acquisition, that is, a stage in which there
is no syntactic (constituent) structure. Such a possibility does not exist in the Borer and Wexler theory.
Gleitman (1981), while not committing herself to a maturational theory or to a semantic stage, presented
clear arguments that if the child system did contain a semantic stage, the only way that this stage could
develop into the adult system (which we know does have a rich syntactic component) would be
maturationally and not via learning.
The term triggering data simply means the evidence or input that causes a learning event, e.g.,
the input that causes the resetting of a parameter value.
The cases are often quite simple from a performance point of view, so performance factors
cannot be the explanation. An attempt to explain the developmental delay using some kind of learning
theory might assume that the child was cognitively immature, whlch would make certain meanings not
available. But note that this invokes maturation, although maturation of cognitive as opposed to
linguistic ability. That might sometimes play a role, but the cases are often cognitively simple. There
is very little independent empirical basis to claim that the necessary cognitive aspects of language
acquisition are difficult until a certain age. Such evidence would be necessary to substantiate a claim
that it is cognitive immaturity that is at work. At any rate, such a possibility still invokes innateness
and maturation, although cognitive rather lhan linguistic.
Within linguistic-theory approaches to language acquisition, there is controversy about whether
maturation plays a significant role in grammatical development. Probably the predominant view still is
that ~hildrenare born with UG and that other factors cover this over. However, there is active research
and discussion on the topic, carried out in specific terms. For an argument against maturation see, for
example, Weinberg, in press.
The argument that English-speaking children go through such a "null subject" stage is originally
in the important work of Hyams, 1986, 1987. Now it is known that French children also go through
such a stage, although null subjects are not grammatical in adult French either (Pierce, 1989; Weissenborn, 1988). Suggestions that the null subject stage does not reflect the lack of grammatical knowledge
but rather reflects a processing deficiency may be found in L. Bloom, 1970; P. Bloom, 1990. Detailed
arguments that such a stage represents grammatical knowledge and is not a "processing" stage are to
be found in Hyams and Wexler, 1989. If it turns out that the null subject stage does not represent a
lack of grammatical knowledge in English-speaking children, then the evidence for innateness would
be even stronger; it would mean that children less than two years old already knew a number of rather
subtle grammatical distinctions between English and Italian.
For discussion see Nadel and Wexler, 1984; Wexler, 1982, in press.
'
*
658
WEXLER
For example, Piaget argued that he was a Kantian, except that Kant did not allow for the
development of innate principles, and he (Piaget) did. It is not clear that Piaget used the same sense
of innateness as we are discussing here; rather, probably not. See the articles in Piattelli-Palmarini,
1980 for extensive discussion.
lo An example very much to the point is the recent proliferation of "connectionist" ideas. The
general idea of connectionism is that large unstructured neural networks can "learn" complex cognitive
structures, without any innate representational assumptions. There are only a small handful, at most,
of articles trying to explain language learning in "co~ectionist" terms, and these concentrate on the
peripheral aspects of linguistic competence. Thus Rumelhart and McClelland, 1986, probably the most
well known of these studies, attempts to explain how the past tense forms of verbs might be learned
via a connectionist system. Pinker and Prince, 1988, show how the connectionist model for this learning
is empirically wrong, in contrast to a rule-based account. Thus the connectionist model (a kind of
general-purpose learning model) is quite inadequate even for this extremely limited problem of the
memorization of the forms of past-tense verbs, and no attempt at all is made to deal with the wide
variety of intensively studied phenomena of linguistic development that go orders of magnitude beyond
the phenomena actually studied in the model.
" Furthermore, the possibility that certain linguistic abilities might be innate leads to the possibility of finding direct genetic evidence for these abilities. Gopnik, (in press) has found evidence that
specific language deficit is genetically inherited.
IZ The definition of "locality" must be given in structural terms-I will not do this here.
l3 The basic universal principles concerning binding of reflexives were described in Chomsky,
1981. Linguistic variation in antecedents of reflexives has been studied in many works. Articles that
synthesize the empirical literature, following the approach sketched in the text, are Manzini and Wexler
(1987) and Wexler and Manzini (1987). The idea for the Subset Principle can be found in many works.
It was formulated and named by Berwick (1985) and studied in detail in the two papers by Manzini and
Wexler mentioned above. There are many articles on the development of reflexives by children. These
include Wexler and Chien (1985) and Chien and Wexler (in press), which can beconsulted for other
references. The results concerning the development of the "local" value of the antecedent parameter
before the "long-distance" value are in Lee and Wexler (1987) for Korean and Chien and Wexler
(1987) for Chinese. The results I have been describing are the subject of extensive research by many
psychologists and linguists, and I hope it is understood that I have simplified greatly.
l4 See Wexler and Culicover (1980) for a detailed mathematical study of the learnability of linguistic
theory and Osherson, Stob and Weinstein (1986) for a study less tied to linguistic structures.
l5 I exclude Lamarkian considerations, etc.
l6 See Wexler and Culicover (1980) for a review of this literature to that date.
I' This does not mean, of course, that thegenes must code every aspect of the developed organism.
Internal physical mechanisms that arise during development may also play an important role.
I would like to thank Lila Gleitman and Steve Pinker for discussion and Cathy Dent, Patricia
Zukow, and two anonymous reviewers for helpful comments on the first draft. The preparation of this
paper was supported by National Science Foundation grants #IN-851 1348 and #882-0585ENS.
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Input, Innateness, and
I
Language Acquisition
JAMES L. MORGAN
Department of Cognitive and Linguistzc Sciences
Brown University
Providence, Rhode Island
Input and innateness compliment one another in language acquisition. Children exposed t o difS
ent languages acquire different languages. Children's language experience, however, underdetermir
the grammars that they acquire; the constraints that are not supplied by input must be availal
endogenously, and the ultimate origin of these endogenous contributions to acquisition may be trac
to the biology of the mind. To the extent that assumptions of innateness encourage greater explicitnt
in the formulation of theories of acquisition, they should be welcomed. Excessively powerful assun
tions of innateness may not be subject to empirical disconfirmation, however. Therefore, attenti
should be devoted to the development of a theory of language input, particularly with regard
identifying invariants of input. In combination with a linguistic theory providing an account of the er
state of acquisition, a theory of input would permit the deduction of properties of the mind that under
the acquisition of language.
Language is the product of the child's attending to, representing, and analyzi~
linguistically relevant input in a fashion sanctioned by imperatives of hum;
nature. This interactional position is acceded to by virtually all theorists, includil
. strong nativists such as Chomsky, who, in outlining the goals of the study
language, has written:
We must determine how the child comes to master the rules and principles that constitute
the mature system of knowledge of language. The problem is an empirical one. In
principle, the source of such knowledge might lie in the child's environment or in the
biolog~callydetermined resources of the mindlbrain, specifically, that component of the
mindlbrain that we might call the language faculty; interaction of these factors provides
the system of knowledge that is put to use in speaking and understanding. (1988, p. 15)
In this article, I advocate an intermediate position on the question of innatene
in language acquisition. Several arguments lead irresistibly to the conclusion th
Reprint requests should be sent to Dr. James L. Morgan, Department of Cognitive and Linguist
Sciences, Brown University, Box 1978, Providence, Rhode Island 02912.
Received for publication I September 1988
Revised for publication 30 August 1989
Accepted at Wiley 13 July 1990
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