syntAX

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After a lecture on cosmology and the structure of the solar system, William Jameswas accosted by a little old lady who told him that his view of the earth rotating round the sun was wrong.
“I’ve got a better theory,” said the little old lady.

“And what is that, madam?” inquired James politely.

“That we live on a crust of earth which is on the back of a giant turtle.”

“If your theory is correct, madam,” he asked, “what does this turtle stand on?”

“You’re a very clever man, Mr. James, and that’s a very good question,” replied the little old lady,

“but I have an answer to it. And it’s this: the first turtle stands on the back of a second, far

larger, turtle, who stands directly under him.”

“But what does this second turtle stand on?” persisted James patiently.

To this, the little old lady crowed triumphantly, “It’s no use,Mr. James, it’s turtles all the way down.” Adapted from Ross (1967)

 In the last chapter, we moved from the general categories and concepts of traditional grammar to more specific methods of describing the structure of phrases and sentences. When we concentrate on the structure and ordering of components within a sentence, we are studying the syntax of a language. The word “syntax” comes originally from Greek and literally means “a putting together” or “arrangement.” In earlier approaches to the analysis of syntax, as we saw in Chapter 7, there was an attempt to produce an accurate description of the sequence or ordering “arrangement” of elements in the linear structure of the sentence. In more recent attempts to analyze syntactic structure, there has been a greater focus on the underlying rule system that we use to produce or “generate” sentences.

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Syntax

When we set out to provide an analysis of the syntax of a language, we try to adhere to the “all and only” criterion. This means that our analysis must account for all the grammatically correct phrases and sentences and only those grammatically correct phrases and sentences in whatever language we are analyzing. In other words, if we write rules for the creation of well-formed structures, we have to check that those rules, when applied logically, won’t also lead to ill-formed structures.

For example, we might say informally that, in English, we put a preposition (near) before anoun(London) to formaprepositional phrase(near London). However, if we use this as a rule of the grammar to create structures, we will end up producing phrases like *near tree or *with dog. These don’t seem to be grammatically correct, so we mark them with an asterisk *. We clearly need to be more careful in forming this rule. We might have more successwith a rule stating thatwe put a preposition before a noun phrase (not just a noun). In Chapter 7,we saw that a noun phrase can consist of a proper noun (London), a pronoun (you) or a combination of an article (a, the) and a noun (tree, dog), so that the revised rule can produce thesewell-formed structures: near London, with you, near a tree, with the dog. 

When we have an effective rule such as “a prepositional phrase in English consists of a preposition followed by a noun phrase,” we can imagine an extremely large number of English phrases that could be produced using this rule. In fact, the potential number is unlimited. This reflects another goal of syntactic analysis, which is to have a small and finite (i.e. limited) set of rules that will be capable of producing a large and potentially infinite (i.e. unlimited) number of well-formed structures. This small and finite set of rules is sometimes described as a generative grammar because it can be used to “generate” or produce sentence structures and not just describe them.

This type of grammar should also be capable of revealing the basis of two other phenomena: first, how some superficially different sentences are closely related and, second, how some superficially similar sentences are in fact different.

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Deep and surface structure

Two superficially different sentences are shown in these examples:

In traditional grammar, the first is called an active sentence, focusing on what Charlie did, and the second is a passive sentence, focusing on The window and what happened to it. The distinction between themis a difference in their surface structure, that is, the different syntactic forms they have as individual English sentences. However, this superficial difference in form disguises the fact that the two sentences are very closely related, even identical, at some less superficial level.

This other “underlying” level, where the basic components (Noun Phrase+Verb+ Noun Phrase) shared by the two sentences can be represented, is called their deep structure. The deep structure is an abstract level of structural organization in which all the elements determining structural interpretation are represented. That same deep structure can be the source of many other surface structures such as It was Charlie who broke the window and Was the window broken by Charlie?. In short, the grammar must be capable of showing how a single underlying abstract representation can become different surface structures.

Structural ambiguity

Let’s say we have two distinct deep structures. One expresses the idea that “Annie had an umbrella and she bumped into a man with it.” The other expresses the idea that “Annie bumped into a man and the man happened to be carrying an umbrella.” Now, these two different versions of events can actually be expressed in the same surface structure form: Annie bumped into a man with an umbrella. This sentence provides an example of structural ambiguity. It has two distinct underlying interpretations that have to be represented differently in deep structure.

The comedian Groucho Marx knew how to have fun with structural ambiguity. In the filmAnimal Crackers, he first says I once shot an elephant inmy pajamas, then follows it with How he got into my pajamas I’ll never know. In the non-funny interpretation, part of the underlying structure of the first sentence could be something like: “I shot an elephant (while I was) in my pajamas.” In the other (ho, ho) interpretation, part of the underlying structure would be something like: “I shot an elephant (which was) in my pajamas.” There are two different underlying structures with the same surface structure.

Phrases can also be structurally ambiguous, as in expressions like small boys and girls. The underlying interpretation can be either “small boys and (small) girls” or “small boys and (all) girls.” Our syntactic analysis will have to be capable of showing the structural distinction between these underlying representations.

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Recursion

The rules of the grammar will also need the crucial property of recursion. Recursive (“repeatable any number of times”) rules have the capacity to be applied more than once in generating a structure. For example, we can have one prepositional phrase describing location (on the table) in the sentence The gun was on the table. We can also repeat this type of phrase, using different words (near the window), for as long as the sentence still makes sense (in the bedroom). So, in order to generate a sentence such as The gunwas on the table near the window in the bedroom, we must be able to repeat the rule that creates a prepositional phrase over and over again.

We must also be able to put sentences inside other sentences. For example, when we produce a sentence such as Cathy knew that Mary helped George, we do so with the sentence Mary helped George inside it. And those two sentences can be generated inside another sentence such as John believed that Cathy knew that Mary helped George. In principle, there is no end to the recursion that would produce ever longer versions of complex sentences with this structure.

Basically, the grammar will have to capture the fact that a sentence can have another sentence inside it or that a phrase can be repeated as often as required. We should note that recursion of this type is not only a feature of grammar, but can also be an essential part of a theory of cosmic structure, as in the role of turtles in one little old lady’s view of the universe (in the introductory quotation).

Tree diagrams

One of the most common ways to create a visual representation of syntactic structure is through tree diagrams.We can use the symbols introduced in Chapter 7 (Art=article, N = noun, NP = noun phrase) to label parts of the tree as we try to capture the hierarchical organization of those parts in the underlying structure of phrases and sentences. So, we can take the information in a labeled and bracketed format, shown on the left, and present it in a tree diagram, shown on the right.

Although this kind of “tree,” with its “branches,” shown on the right, seems to grow down rather than up, it functions rather well as a diagram representing all the grammatical information found in the other analysis on the left. It also shows very explicitly that there are different levels in the analysis. That is, there is a level of analysis at which a constituent such as NP is represented and a different, lower, level at

which a constituent such as Nis represented. This type of hierarchical organization can be illustrated in a tree diagram for a whole sentence, beginning at the top with S.

If we start at the top of the tree diagram, we begin with a sentence (S) and divide it into two constituents (NP and VP). In turn, the NP constituent is divided into two other constituents (Art and N). Finally, one word is selected that fits the label Art (the) and another that fits N (girl). You can go through the same procedure with the

VP branches.

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We have already encountered some symbols that are used as abbreviations for syntactic categories. Examples are “S” (= sentence), “NP” (= noun phrase), “N” (= noun), “Art” (= article), “V” (= verb) and “VP” (= verb phrase). Others, such as “PP” (= prepositional phrase), seem fairly transparent. There are three more symbols that are commonly used in syntactic description.

The first is in the form of an arrow →. It can be interpreted as “consists of” or “rewrites as.” It is typically used in the following type of rule:

This is simply a shorthand way of saying that a noun phrase (NP) such as the dog consists of or rewrites as (→) an article (Art) the and a noun (N) dog. The second symbol is a pair of round brackets ( ). Whatever occurs inside these round brackets will be treated as an optional constituent. For example, we can describe something as the dog or the small dog. We can say that both the dog and the small dog are examples of the category noun phrase (NP). When we want to use a noun phrase in

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English, we can include an adjective (Adj) such as small, but we don’t have to. It’s an optional constituent in a grammatically well-formed noun phrase. We can represent this observation in the following type of rule:

This shorthand notation expresses the idea that a noun phrase rewrites as (→) an article (Art) and a noun (N), with the option of including an adjective (Adj) in a specific position between them. We use the round brackets to indicate that the adjective is optional. So, we can use this notation to generate the dog, the small dog, a cat, a big cat, the book, a boring book and an endless number of other similar noun phrases.

The third symbol is in the form of curly brackets { }.These indicate that only one of the elements enclosed within the curly brackets must be selected. We use these types of brackets when we want to indicate that there is a choice from two or more constituents. For example, we have seen already that a noun phrase can consist of an expression such as the dog (article plus noun), or it (pronoun), or Cathy (proper noun). Using the abbreviations “Pro” (for pronoun) and “PN” (for proper noun), we can try to capture this observation about English with three separate rules, as shown on the left. However, it is more succinct to write one rule, as shown in the middle or on the right, using curly brackets and including exactly the same information. 

It is important to remember that, although there are three constituents inside these curly brackets, only one of them can be selected on any occasion. The list of common symbols and abbreviations is summarized here.

S sentence          NP noun phrase     PN proper noun

N noun               VP verb phrase      Adv adverb

V verb                Adj adjective         Prep preposition

Art article          Pro pronoun           PP prepositional phrase

* ungrammatical sentence

→ consists of / rewrites as

( ) optional constituent

{ } one and only one of these constituents must be selected

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Phrase structure rules

When we use a tree diagram format, we can think of it in two different ways. In one way, we can simply treat it as a static representation of the structure of the sentence shown at the bottom of the diagram. We could then propose that, for every single sentence in English, a tree diagram of this type could be drawn. An alternative view is to treat the tree diagram as a dynamic format, in the sense that it represents a way of generating not only that one sentence, but a very large number of other sentences with similar structures.

This second approach is very appealing because it would enable us to generate a very large number of sentences with what look like a very small number of rules. These rules are called phrase structure rules. As the name suggests, these rules state that the structure of a phrase of a specific type will consist of one or more constituents in a particular order. We can use phrase structure rules to present the information of the tree diagram in another format. That is, the information shown in the tree diagram on the left can be expressed in the phrase structure rule on the right.

    NP

Art N             NP -> Art N

According to this rule, “a noun phrase rewrites as an article followed by a noun.” The first rule in the following set of simple (and necessarily incomplete) phrase structure rules states that “a sentence rewrites as a noun phrase and a verb phrase.” The second rule states that “a noun phrase rewrites as either an article plus an optional adjective plus a noun, or a pronoun, or a proper noun.” The other rules follow a similar pattern.

S → NP VP

NP → {Art (Adj) N, Pro, PN}

VP → V NP (PP) (Adv)

PP → Prep NP

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Lexical rules

Phrase structure rules generate structures. In order to turn those structures into recognizable English, we also need lexical rules that specify which words can be used when we rewrite constituents such as N. The first rule in the following set states that “a proper noun rewrites as Mary or George.” (It’s a very small world.)

PN → {Mary, George}

N → {girl, dog, boy}

Art → {a, the}

Pro → {it, you}

V → {followed, helped, saw}

We can rely on these rules to generate the grammatical sentences shown below as (1) to (6), but not the ungrammatical sentences shown as (7) to (12).

(1) A dog followed the boy. (7) *Dog followed boy.

(2) Mary helped George. (8) *The helped you boy.

(3) George saw the dog. (9) *George Mary dog.

(4) The boy helped you. (10) *Helped George the dog.

(5) It followed Mary. (11) *You it saw.

(6) You saw it. (12) *Mary George helped.

As a way of visualizing how the phrase structure rules form the basis of these sentences, we can draw the tree diagrams for sentences (1) and (6).

(1)        S                                                   (6) S

       NP              VP                             NP             VP

     Art N          V NP                          Pro           V NP

                           Art N                                         Pro

A dog followed the boy You saw it

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Movement rules

The very small set of phrase structure rules just described is a sample of what a more complex phrase structure grammar of English, with many more parts, would look like. These rules can be treated as a representation of the underlying or deep structures of sentences in English. One feature of these underlying structures is that they will generate sentences with a fixed word order. That is convenient for creating declarative forms (You will help Mary), but not for making interrogative forms, as used in questions (Will you help Mary?). In making the question, we move one part of the structure to a different position. This process is based on a movement rule.

In order to talk about this process, we need to expand our phrase structure rules to include an auxiliary verb (Aux) as part of the sentence. This is illustrated in the first rewrite rule below. Auxiliary verbs (sometimes described as “helping” verbs) take different forms in English, but one well-known set can be included in the rudimentary lexical rule for Aux below. We also need a lexical rule that specifies the basic forms of the verbs, shown as the third rewrite rule below.

S → NP Aux VP

Aux → {can, could, should, will, would}

V → {follow, help, see}

With these components, we can specify a simple movement rule that is involved in the creation of one basic type of question in English.

NP Aux VP ⇒ Aux NP VP

This type of rule has a special symbol ⇒ and can be illustrated in the process of one tree, on the right, being derived from the tree on the left.

                   S                                 ⇒                                              S

   NP        Aux            VP                                               Aux        NP              VP

  Pro                         V    NP                                                         Pro         V       NP

                                       PN                                                                                  PN

 You        will        help  Mary                                        Will       you      help    Mary

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Using this simple rule, we can also generate these other questions:

Can you see the dog? Should George follow you?

Could the boy see it? Would Mary help George? 

These are all surface structure variations of a single underlying structure. However, we

still have not incorporated recursion.

Back to recursion

The simple phrase structure rules listed earlier have no recursive elements. Each time we start to create an S, we only create a single S (sentence structure). We actually need to be able to include sentence structures within other sentence structures. In traditional grammar, these “sentence structures” were described as “clauses.” We know, for example, that Mary helped George is a sentence. We can put this sentence inside another sentence beginning Cathy knew that [Mary helped George]. And, being tediously recursive, we can put this sentence inside another sentence beginning John believed that [Cathy knew that [Mary helped George]].

In these sentences, two new proper nouns and two new verbs have been used. We have to expand our earlier set of lexical rules to include PN→{John, Cathy} and V→ {believed, knew}. After verbs such as believe and know, as in these examples, the word that introduces a complement phrase. 

Mary helped George. 

Cathy knew that Mary helped George. 

John believed that Cathy knew that Mary helped George.

Complement phrases

The word that, as used in these examples, is called a complementizer (C). The role of that as a complementizer is to introduce a complement phrase (CP). For example, in the second sentence (Cathy knew…), we can identify one CP which contains that plus Mary helped George. We already know that Mary helped George is a sentence (S). So, we are now in a position to define a CP in the following way: “a complement phrase rewrites as a complementizer and a sentence,” or CP → C S.

We can also see from the same sentence that the complement phrase (CP) comes after a verb (V) knew. This means that we are using the CP as part of a verb phrase (VP), as in knew that Mary helped George. So, there must be another rule that says: “a verb phrase rewrites as a verb and complement phrase,” or VP → V CP.

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If we now look at these two new rules in conjunction with an earlier rule, we can see how recursion is built into the grammar.

S → NP VP

VP → V CP

CP → C S

We begin with S on the left and, as we rewrite symbols, we eventually have S on the right, allowing us to go back to the beginning and go through the set of rules again (and again). This means that we can, in principle, use these rules to create an endless sentence containing other sentence structures. In practice, it allows us to draw the following tree diagram and provide a clear representation of the syntactic structure of this one fairly complex sentence.

                          S

NP                                        VP

                V CP

                                             C S

                                          NP VP

                                            V CP

                                               C S

                                           NP VP

                                               V NP

PN            PN            PN              PN

John believed that Cathy knew that Mary helped George

As we try to capture more aspects of the structure of complex English sentences, we inevitably need to identify more rules and concepts involved in the analysis of syntax. (We’ve barely scratched the surface structures.) However, having explored some of the basic issues and methods of syntactic analysis in order to talk about structure in language, we must move on to consider how we might incorporate the analysis of meaning in the study of language.

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