- the sensitive period for language learning and the consequences for first and second language acquisition at a later age (Lenneberg 1967, Curtiss 1977, Newport 1990, Flynn and O’Neill 1988, Klein and Perdue 1997)
- the limited ability of apes to acquire even rudimentary versions of human language, even with extensive training (Premack 1976, Seidenberg and Petitto 1978, Terrace 1979, Savage-Rumbaugh et al. 1998)
- the characteristic brain localization of language functions, resulting in characteristic aphasias (Zurif 1990)
- the grammatical parallels between spoken and signed languages and the parallels in acquisition and aphasia (Klima and Bellugi 1979, Bellugi, Poizner, and Klima 1989, Fischer and Siple 1990)
- the existence of characteristic language deficits associated with various genetic conditions (Bellugi et al. 1994, Gopnik 1999, Clahsen and Almazan 1998)
- the creation of creole languages by communities of pidgin-speaking children (Bickerton 1981, DeGraff 1999)
- most strikingly, the creation of a signed language de novo by a newly assembled community of deaf children in Nicaragua (Kegl et al. 1999)
My impression is that, while there are questions about
all of these cases, en masse they offer an overwhelming case for some degree of
genetic specialization for language learning in humans.
These three foundational issues of generative grammar
– mentalism, combinatoriality, and acquisition – have stood the test of time;
if anything they have become even more important over the years in the rest of
cognitive science. It is these three
issues that connect linguistics intimately with psychology, brain science, and
genetics. Much of the promise of
generative linguistics arose from this new and exciting potential for
scientific unification.
3. The broken
promise: Deep Structure would be the key to the mind
A fourth major point of Aspects, and the one
that seeped most deeply into the awareness of the wider public, concerned the
notion of Deep Structure. A basic claim
of the 1965 version of generative grammar was that in addition to the surface
form of sentences, i.e. the form we hear, there is another level of syntactic
structure, called Deep Structure, which expresses underlying syntactic
regularities of sentences. For
instance, a passive sentence like (1a)
has a Deep Structure in which the noun phrases are in the order of the
corresponding active (1b).
(1) a. The bear was chased by the lion.
b. The lion chased the bear.
Similarly, a question such as (2a) has a Deep
Structure closely resembling that of the corresponding declarative (2b).
(2) a. Which martini did Harry drink?
b. Harry drank that martini.
In the years preceding Aspects, the question
arose of how syntactic structure is connected to meaning. Following a hypothesis first proposed by
Katz and Postal (1964), Aspects made the striking claim that the
relevant level of syntax for determining meaning is Deep Structure.
In its weakest version, this claim was only that
regularities of meaning are most directly encoded in Deep Structure, and this
can be seen in (1) and (2). However,
the claim was sometimes taken to imply much more: that Deep Structure IS meaning, an interpretation that
Chomsky did not at first discourage.3 And this was the part of generative
linguistics that got everyone really excited.
For if the techniques of transformational grammar lead us to meaning, we
can uncover the nature of human thought.
Moreover, if Deep Structure is innate – being dictated by Universal
Grammar – then linguistic theory gives us unparalleled access to the essence of
human nature. No wonder everyone
wanted to learn linguistics.
What happened next was that a group of generative
linguists, notably George Lakoff, John Robert Ross, James McCawley, and Paul
Postal, pushed very hard on the idea that Deep Structure should directly encode
meaning. The outcome, the theory of
Generative Semantics (e.g. McCawley 1968, Postal 1970, Lakoff 1971), increased
the “abstractness” and complexity of Deep Structure, to the point that the
example Floyd broke the glass was famously posited to have eight
underlying clauses, each corresponding to some feature of the semantics. All the people who admired Aspects
for what it said about meaning loved Generative Semantics, and it swept the
country. But Chomsky himself reacted
negatively, and with the aid of his then-current students (full
disclosure: present author included),
argued vigorously against Generative Semantics. When the dust of the ensuing“Linguistics Wars” cleared around
1973 (Newmeyer 1980, Harris 1993, Huck and Goldsmith 1995), Chomsky had won –
but with a twist: he no longer claimed
that Deep Structure was the sole level that determines meaning (Chomsky
1972). Then, having won the battle, he
turned his attention, not to meaning, but to relatively technical constraints
on movement transformations (e.g. Chomsky 1973, 1977).
The reaction in the larger community was shock: for one thing, at the fact that the
linguists had behaved so badly; but more substantively, at the sense that there
had been a “bait and switch.” Chomsky
had promised Meaning with a capital M and then had withdrawn the
offer. Many researchers, both inside
and outside linguistics, turned away from generative grammar with disgust,
rejecting not only Deep Structure but mentalism, innateness, and sometimes even
combinatoriality. And when, later in
the 1970s, Chomsky started talking about meaning again, in terms of a syntactic
level of Logical Form (e.g. Chomsky 1981), it was too late: the damage had been done. From this point on, the increasingly
abstract technical apparatus of generative grammar was of no interest to more than
a tiny minority of cognitive scientists, much less the general public.
Meanwhile, various nonChomskyan traditions of
generative grammar developed, most notably Relational Grammar (Perlmutter
1983), Head-Driven Phrase Structure Grammar (Pollard and Sag 1987, 1994),
Lexical-Functional Grammar (Bresnan 1982, 2001), Formal Semantics (Partee 1976,
Heim and Kratzer 19xx), Optimality Theory (Prince and Smolensky 1993),
Construction Grammar (Fillmore et al. 1988, Goldberg 1995), and Cognitive
Grammar (Lakoff 1987, Langacker 1987, Talmy 2000). On the whole, these approaches to linguistics (with the possible
exception of Cognitive Grammar) have made even less contact with philosophy,
psychology, and neuroscience than the recent Chomskyan tradition. My impression is that many linguists have
simply returned to the traditional concerns of the field: describing languages,
with as little theoretical and cognitive baggage as possible. While this is perfectly fine – particularly
since issues of innateness don’t play too big a role when you’re trying to record
an endangered language before its speakers all die – the sense of excitement
and danger that comes from participating in the integration of fields has
become attenuated.
4. The
scientific mistake: syntactocentrism
So much for pure intellectual history. We now turn to what I think was an important
mistake at the core of generative grammar, one that in retrospect lies behind
much of the alienation of linguistic theory from the cognitive sciences. Chomsky did demonstrate that language
requires a generative system that makes possible an infinite variety of
sentences. However, he explicitly
assumed, without argument (1965: 16, 17, 75, 198), that generativity is
localized in the syntactic component of the grammar – the construction of
phrases from words – and that phonology
(the organization of speech sounds) and semantics (the organization of meaning)
are purely “interpretive”, that is, that their combinatorial properties are
derived strictly from the combinatoriality of syntax.
In 1965 this was a perfectly reasonable view. The important issue at that time was to show
that something in language is generative. Generative syntax had provided powerful new tools, which were
yielding copious and striking results.
At the time, it looked as though phonology could be treated as a sort of
low-level derivative of syntax: the syntax gets the words in the right order,
then phonology massages their pronunciation to adjust them to their local
environment. As for semantics,
virtually nothing was known: the only
things on the table were the rudimentary proposals of Katz and Fodor (1963) and
some promising work by people such as Bierwisch (1967, 1969) and Weinreich
(1966). So the state of the theory
offered no reason to question the assumption that all combinatorial complexity
arises from syntax.
Subsequent shifts in mainstream generative linguistics
stressed major differences in outlook.
But one thing that remained unchanged was the assumption that syntax is
the sole source of combinatoriality.
Figure 1 diagrams the architecture of components in three major stages
of Chomskyan syntactic theory: the Aspects theory, Principles and
Parameters (or Government-Binding) Theory (Chomsky 1981), and the Minimalist
Program (Chomsky 1995). The arrows
denote direction of derivation.
Figure 1. Architecture of Chomsky's theories over the years.
These shifts alter the components of syntax and their
relation to sound and meaning. What
remains constant throughout, though, is that (a) there is an initial stage of
derivation in which words or morphemes are combined into syntactic structures;
(b) these structures are then massaged by various syntactic operations; and (c)
certain syntactic structures are shipped off to phonology/phonetics to be
pronounced and other syntactic structures are shipped off to “semantic
interpretation” to be understood. In
short, syntax is the source of all linguistic organization.
I believe that this assumption of “syntactocentrism” –
which, I repeat, was never explicitly grounded – was an important mistake at the heart of the field.4 The correct approach is to regard linguistic
structure to be the product of a number of parallel but interacting generative
capacities – at the very least, one each for phonology, syntax, and
semantics. As we will see, elements of
such a “parallel architecture” have been implicit in practice in the field for
years. What is novel in the present
work is bringing these practices out into the open, stating them as a
foundational principle of linguistic organization, and exploring the
large-scale consequences.
5. Phonology
as an exemplar of the parallel architecture
An unnoticed crack in the assumption of
syntactocentrism appeared in the middle to late 1970s, when the theory of
phonology underwent a major seachange.
Before then, the sound system of language had been regarded essentially
as a sequence of speech sounds. Any
further structure, such as the division into words, was thought of as simply
inherited from syntax. However, beginning with work such as Goldsmith (1979)
and Liberman and Prince (1977), phonology rapidly came to be thought of as
having its own autonomous structure, in fact multiple structures or tiers. Figure 2 provides a sample, the structure of
the phrase the big apple. The
phonological segments appear at the bottom, as terminal elements of the
syllabic tree.
Figure 2. Phonological structure of the big apple.
There are several innovations here. First, syllabic structure is seen as
hierarchically organized. At the center
of the syllable (notated as σ) is a syllabic nucleus (notated N),
which is usually a vowel but sometimes a syllabic consonant such as the l
in apple. The material following
the nucleus is the syllabic coda (notated C); this groups with the
nucleus to form the rhyme (notated R), the part involved in
rhyming. In turn, the rhyme groups with
the syllabic onset (notated O) to form the entire syllable. Syllables are grouped together into larger
units such as feet and phonological words (here, the bracketing subscripted Wd). Notice that in Figure 1, the word the
does not constitute a phonological word on its own; it is attached (or
cliticized) onto the word big.
Finally, phonological words group into larger units such as phonological
phrases. Languages differ in their
repertoire of admissible nuclei, onsets, and codas, but the basic hierarchical
organization and the principles by which strings of segments are divided into syllables
are universal. (It should also be
mentioned that signed languages have parallel syllabic organization, except
that the syllables are built out of manual rather than vocal constituents
(Klima and Bellugi 1979, Fischer and Siple 1990).)
These hierarchical structures are not built out of
syntactic primitives such as nouns, verbs, and determiners; their units are
intrinsically phonological. In
addition, the structures, though hierarchical, are not recursive.5 Thus the principles governing these structures
are not derivable from syntactic structures; they are an autonomous system of
generative rules.
Next consider the metrical grid in Figure 2. Its units are beats, notated as
columns of xs. A column with
only one x is a weak beat, and more xs in a column indicate a
relatively stronger beat. Each beat is
associated with a syllable; the strength of a beat indicates the relative
stress on that syllable, so that for example in Figure 2 the first syllable of apple
receives maximum stress. The basic principles
of metrical grids are in part autonomous of language: they also appear, for instance, in music (Lerdahl and Jackendoff
1983), where they are associated with notes instead of syllables. Metrical grids place a high priority on
rhythmicity: an optimum grid presents an alternation of strong and weak beats,
as is found in music and in much poetry.
On the other hand, the structure of syllables exerts an influence on the
associated metrical grid: syllables
with heavy rhymes (i.e. containing a coda or a long vowel) “want” to be
associated with relatively heavy stress.
The stress rules of a language concern the way syllabic structure comes
to be associated with a metrical grid; languages differ in ways that are now
quite well understood (e.g. Kager 1995, Halle and Idsardi 1995).
Again, metrical grids are built of nonsyntactic
units. As they are to some degree
independent of syllabic structure, they turn out to be a further autonomous
“tier” of phonological structure.
At a larger scale of phonological organization we find
prosodic units over which intonation contours are defined. These are comparable in size to syntactic
phrases but do not coincide with them.
Here are two examples.
(3) Syntactic
bracketing:
[Sesame
Street] [is [a production [of [the Children’s Television Workshop]]]]
Prosodic
bracketing (two pronunciations):
a. [Sesame Street is a production of] [the
Children’s Television Workshop]
b. [Sesame Street] [is a production] [of the
Children’s Television Workshop]
(4) Syntactic
bracketing
[This]
[is [the cat [that chased [the rat [that ate [the cheese]]]]]]
Prosodic
bracketing:
[This is
the cat] [that chased the rat] [that ate the cheese]
The two pronunciations of (3) are both acceptable, and
other prosodic bracketings are also possible.
However, the choice of prosodic bracketing is not entirely free, since
for instance [Sesame] [Street is a production of the] [Children’s Television
Workshop] is an impossible phrasing.
Now notice that the first constituent of (3a) and the second constituent
of (3b) do not correspond to any syntactic constituent. We would be hard pressed to know what
syntactic label to give to Sesame Street is a production of. But as an intonational constituent it
is perfectly fine. Similarly in (4),
the syntax is relentlessly right-embedded, but the prosody is flat and
perfectly balanced into three parts.
Again, the first two constituents of the prosody do not correspond to
syntactic constituents of the sentence.
The proper way to deal with this lack of correspondence
is to posit a phonological category of Intonational Phrase, which plays a role
in the assignment of intonation contours and the distribution of stress
(Beckman and Pierrehumbert 1986, Ladd 1996).
Intonation Phrases are to some degree correlated with syntax; their
boundaries tend to be at the beginning of major syntactic constituents; but
their ends do not necessarily correlate with the ends of the
corresponding syntactic constituents.
At the same time, intonational phrases have their own autonomous
constraints, in particular a strong preference for rhythmicity and parallelism
(as evinced in (2) for example), and a preference for saving the longest
prosodic constituent for the end of the sentence.6
Another example of mismatch between syntax and
phonology comes from contractions such as I’m and Lisa’s (as in Lisa’s
a doctor). These are clearly
phonological words, but what is their syntactic category? It is implausible to see them either as noun
phrases that incidentally contain a verb or to see them as verbs that
incidentally contain a noun. Keeping
phonological and syntactic structure separate allows us to say the natural
thing: they are phonological words that
correspond to two separate syntactic constituents.
(5) Syntactic
structure: [NP I] [V
(a)m] [NP Lisa] [V
(i)s]
Phonological
structure: [Wd
I’m] [Wd Lisa’s]
Since every different sentence of the language has a
different phonological structure, and since phonological structures cannot be
derived from syntax, the usual arguments for combinatoriality lead us to the
conclusion that phonological structure is generative. However, in addition to the generative principles that describe
these structures, it is necessary to introduce a new kind of principle into the
grammar, what might be called “correspondence rules” or “interface rules.” These rules (I revert to the standard term
“rules” rather than being obsessive about “f-rules”) regulate the way the
independent structures correspond with each other. For instance, the relation between syllable weight and metrical
weight is regulated by an interface rule between syllabic and metrical
structure; the relation between syntactic and intonational constituents is
regulated by an interface rule between syntactic and prosodic structure.
An important property of interface rules is they don’t
“see” every aspect of the structures they are connecting. For instance, the rules that connect
syllabic content to metrical grids are totally insensitive to syllable onset:
universally, stress rules care only about what happens in the rhyme. Similarly, although the connection between
syntax and phonology “sees” certain syntactic boundaries, it is insensitive to
the depth of syntactic embedding, Moreover, syntactic structure is totally
insensitive to the segmental content of the words it is arranging (e.g. there
is no syntactic rule that applies only to words that begin with b). Thus interface rules implement not
isomorphisms between the structures they relate, but rather only partial
homomorphisms.
This is not to say that we should think of speakers as
thinking up phonological and syntactic structures independently in the hope
they can be matched up by the interfaces.
That would be the same sort of mistake as thinking that speakers start
with the symbol S and generate a syntactic tree, finally putting in
words so they know what the sentence is about.
At the moment we are not thinking in terms of production; rather we are
stating the principles (of “competence”) in terms of which sentences are
well-formed. We will get back to how
this is related to processing in section 9.3.
Now the main point of this section. This view of phonological structure,
developed in the late 1970s and almost immediately adopted as standard, is
deeply subversive of the syntactocentric assumption that all linguistic
combinatoriality originates in syntax.
According to this view, phonological structure is not just a passive
hand-me-down derived from low-level syntax: it has its own role in shaping the
totality of linguistic structure. But
at the time of these changes, no great commotion was made about this most
radical aspect of the new phonology.
Phonologists for the most part were happy to get on with exploring this
exciting way of doing things, and for them, the consequences for syntax didn’t
matter. Syntacticians, for their part,
simply found phonology irrelevant to
their concerns of constraining movement rules and the like, especially since
phonology had now developed its own arcane technical machinery. So neither subdiscipline really took notice;
and as the technologies diverged, the relation between syntax and phonology
became a no-man’s-land (or perhaps only a very-few-man’s-land). Tellingly, as far as I can determine, in all
of Chomsky’s frequent writings on the character of the human language capacity,
there is no reference at all to post-1975 phonology – much less to the
challenge that it presents to his overall syntactocentric view of language.
6. The
syntax-semantics interface
I have treated the developments in phonology first
because it is less controversial. But
in fact the same thing happened in semantics.
Over the course of the 1970s and 1980s, several radically different
approaches to semantics developed: within
linguistics, at least Formal Semantics (growing out of formal logic)(Partee
1976, Heim and Kratzer 19xx), Cognitive Grammar (Lakoff 1987, Langacker 1987,
Talmy 2000), and Conceptual Semantics (Jackendoff 1983, 1990, Pinker 1989,
Pustejovsky 1995), plus approaches within computational linguistics and
cognitive psychology. Whatever their
differences, all these approaches take meaning to be deeply combinatorial. None of them take the units of semantic
structure to be syntactic units such as NPs and VPs; rather, the units are
intrinsically semantic entities like objects, events, actions, properties, and
quantifiers.7 Therefore,
whichever semantic theory we choose, it is necessary to grant semantics an
independent generative organization, and it is necessary to include in the
theory of grammar an interface component that correlates semantic structures
with syntactic and phonological structures.
In other words, the relation of syntax to semantics is qualitatively parallel
to the relation of syntax to phonology.
However, apparently no one pointed out the challenge to syntactocentrism
– except the Cognitive Grammarians, who mostly went to the other extreme and
denied syntax any independent role, and who have been steadfastly
ignored by mainstream generative linguistics.
The organization of phonological structure into
semi-independent tiers finds a parallel in semantics as well. Linguistic meaning can be readily partialled
into two independent aspects. On one
hand there is what might be called “propositional structure”: who did what to whom and so on. For instance, in The bear chased the lion,
there is an event of chasing in which the bear is the chaser and the lion is
“chasee”. On the other hand, there is
also what is now called “information structure”: the partitioning of the message into old vs. new information,
topic vs. comment, presupposition vs. focus, and so forth. We can leave the propositional structure of
a sentence intact but change its information structure, by using stress (6a-c)
or various focusing constructions (6d-f):
(6) a. The BEAR chased the lion.
b. The bear chased the LION.
c. The bear CHASED the lion.
d. It was the bear that chased the lion.
e. What the bear did was chase the lion.
f. What happened to the lion was the bear chased
it.
Thus the propositional structure and the information
structure are orthogonal dimensions of meaning, and can profitably be regarded
as autonomous tiers. (Foundations
proposes a further split of propositional structure into descriptive and
referential tiers, an issue too complex for the present context.)
Like the interface between syntax and phonology, that
between syntax and semantics is not an isomorphism. Some aspects of syntax make no difference in semantics. For instance, the semantic structure of a
language is the same whether or not the syntax marks subject-verb agreement,
verb-object agreement, or nominative and accusative case. The semantic structure of a language does
not care whether the syntax calls for the verb to be after the subject (as in
English), at
the end of the clause (as in Japanese), or second in a main clause and final in
a subordinate clause (as in German). As
these aspects of syntax are not correlated with or derivable from semantics,
the interface component disregards them.
Similarly, some aspects of semantics have little if
any systematic effect in syntax. Here
are a few well-known examples.