The Basics of Constituent Structure

Part I

Traditional grammar started by identifying eight classes of words:  Noun (table, book, justice, mathematics), Verb (go, sell, compare, reduce), Adjective (green, happy, playful, pliable), Adverb (quickly, soon, playfully, patiently), Pronoun (he, she, it, I, you), Conjunction (and, or, but, because, after), Preposition (to, in, over, on), Interjections (Yikes! Aha! Drat!).  Those were, more or less, the building blocks, and we still use those terms.  But we have more exact and more informative forms of notation for them than we once had, and we’ll be learning a simplified set of those here. 

Basic Definition: We begin with the fact that there are definite rules for how you can build a sentence in any language.  Whatever the language you are speaking, some orders of words make sense to us, and others do not.  Thus in the two English sentences below, one makes sense to speakers of English and the other does not:

I love the man who did the ceiling. 

*Who man the did ceiling love I the.

It is obvious that the second of those sentences makes no sense—but the “why” requires some explanation, and for that we turn to “syntax.”  What the syntax of any language does is specify the rules by which strings of words can be formed into meaningful expressions, and, by contrast, it specifies as well which strings of words cannot.  Here the first sentence is “well-formed” (as a linguist would put it); the second is not well-formed (which is what that asterisk signifies). 

For all languages we can define a sentence as an expression that does two things:  first, it points at some thing or concept or entity in the world, and second, it says something about the thing it has pointed at.  A simple illustration:  “John is tall.”  There we use the word “John” to point, or (more technically) refer to a thing in the world—a human being whose name is John—and we say (or predicate) about that thing that he “is tall.”  The referring expression we call the “subject” of the sentence—the thing about which we are speaking—and the thing we say about that subject is the “predicate” of the sentence. 

Rule:  All complete sentences in any language, English included, must have a subject and a predicate. 

OK.  So referring and predicating are what a sentence does—and how do we capture that as a basis for our syntax? 

First a fact about Nouns and Verbs, the two first building blocks of syntax:  it turns out that referring expressions are what we call “nouns” and predicating expressions are what we call “verbs.”  So (at the simplest of levels) we can say that all sentences must have as constituents at least a noun and a verb, and we can represent that with the expression: 

Sentence → Noun + Verb, or (shortening things up some):
S → N + V

And that is a pretty good description for very simple sentences like:

People slept = People  + slept.
Sally ate = Sally + ate. 
Cats purr = Cats + purr. 

Now S → N + V is obviously more abstract than an actual sentence, but it also clears away the clutter of extra words so we see the bones, as it were, of a sentence’s structure.  Linguists call expressions like S → N + V “phrase-structure rules” because they describe rules for the way phrases (here a sentence) can be successfully constructed. 

So.  S → N + V is a good rule, but it is still not very informative, because English has a lot of words in its sentences other than just Nouns and Verbs.  So we now have to create ways of describing the “internal structure” of subject expressions and predicates.

First about subjects.  While every subject expression (also known as a “referring expression”) must have a noun, it often has other words connected in some way to the main noun.  Thus instead of John we could have said:

                        The man                                 is tall
                        The thin man                          is tall
                        The thin, sprightly man          is tall
                        The very thin, sprightly man  is tall

Here “man” remains the same, but we have added one or more “modifiers” that “determine,” “modify,” or define in some way or another, the general noun “man.”  And as this example set of sentences demonstrates, although subjects of sentences must have a noun, it is also true that most nouns can be modified by adding various modifiers to create a whole phrase instead of just a single word like “John.” 

So the first way we can improve our basic sentence rule (S → N + V) is to change our basic definition of a subject from N (a single noun) to NP (a “noun phrase”) where NP represents an expression that will have [at the very least] an N, but may also include other words that modify that N. 

Similarly, on the predicate side, the symbol V all by itself is also too simple.  It, too, can be a whole phrase, and not just one or two words: 

                        The man ran.
                        The man ran down the street.
                        The man ran the local streetcar.
                        The man ran away from the scene with the detectives in pursuit.

So: predicates, like subjects, may be only one word, but more often they are whole phrases with several words—one of which MUST be a verb.  In the example sentences, the elements that occur along with the V include one or more adverbs. [Thus "away" tells you where he ran; "from the scene" tells you which direction "away" was; "with the detectives in pursuit" describes the manner or condition under which he ran. See "Adverbials" below for more about adverbs.]

Accordingly, we can now revise our S (where S stands for “sentence”) rule above to use both NP and VP instead of just N and V.  Written now more accurately, we can say of an English sentence: 

S → NP  VP 

(Note that we could keep putting plus signs between the elements of the NP and the VP, but we don’t have to because we can assume that the elements of a given string are all combining together anyway, and in the same order, so to put such signs in would be redundant.)

And that, in fact, is our basic “constituent structure” rule—which means simply that if we look at all the basic sentences that English speakers can make or understand, every one of them are constituted by an NP and a VP, or, in more traditional terms, a referring expression and a predicating expression. 

The Structure of Noun Phrases:  With that basic rule set out, we can elaborate that rule by laying out some other constituent structure rules that describe a well-formed noun phrase.  Thus in the set of referring expressions I gave above it is clear that in addition to an N, an NP can also have one or more adjectives (tall, sprightly), along with an adverb (very), and it can have “the”, traditionally thought of as a kind of adjective but now normally called a “determiner,” since it helps us determine the scope of a given noun.  Here we are talking about not just any man, but THE man—a person both speaker and hearer of the sentences know from a preceding context.  Here are some other referring expressions that are well-formed in English: 

The intelligent man
The very intelligent man
The very tall, intelligent man
The very extremely tall, intelligent man

Obviously, NP’s—here grouped with adjectives and adverbs, along with a determiner—can have a number of different parts.  But that’s ok.  We’ll just modify our basic constituent structure rule to include all of those possibilities: 

NP → (det)(adv)*(adj)*N

Here the asterisk means “one or more,” indicating that we can repeat that particular element if we want, and the parentheses represent the fact that some constituents of the NP are optional.  Indeed, ALL of the constituents are optional EXCEPT the N

We’d read that rule aloud as “A noun phrase can go to an optional determiner followed optionally by one or more adverbs and one or more adjectives, preposed to the noun that they modify.” 

Now, I know that this seems very mathematical, and therefore not very user friendly.  But at the same time you can see why the formal notion is valuable.  NP → (det)(adv)*(adj)*N is a lot simpler to say or write than “A noun phrase can go to an optional determiner followed optionally by one or more adverbs and one or more adjectives, preposed to the noun that they modify”!    

The Structure of Verb Phrases:  Having looked at simple NPs, we can now move to English’s VP constituents.  Consider the following set of predicate expressions:

John eats bread

eats the bread
eats the cold bread
eats the old, cold bread

Here we have a verb (eats) followed by a noun (bread), and then that same noun with various modifiers—in fact (and here is the first place where things may start to get a little easier) what we see here is a phrase that uses the very same structure we just defined as an NP!  So we don’t have to make up new rules for this NP.  Instead we can say of a predicate that in addition to a single V, it can also have other constituents, and one of those can be an NP—since any noun that follows a verb can itself be modified in the very same way that a noun used as a subject can be modified.  So we can now write: 

VP → V (NP)

But that isn’t all we do with VPs.  We have other constituents that can be included in a predicate, as in the sentence:  John eats the old, cold bread slowly.  There we have added “slowly,” which is an adverb, since (as adverbs always do) it modifies the verb—describing HOW John eats.  (Adverbs typically answer the questions Where, When, Why, How, With What, or With Respect to Whom.)  So now we can modify our VP expression further—and we will add not just parentheses to the ADV, since a V does not HAVE to have an adverb attached, but we will add an asterisk as well since it can have more than one: 

                                            VP→V (NP) (ADV)*

So if we had the sentence "The very hot oatmeal burned the woman's tongue badly" we can now see that the string of words in the sentence are actually a NP followed by a V which is then followed by another NP and by an ADV. The first NP is "The very hot oatmeal"; the verb, or V, is "burned"; "her tongue" is an NP which is the thing that the oatmeal burned; and, finally, "badly" is an adverb, or ADV, describing "how much" or "in what way" the woman was burned.


Part II

Part I above gave you three rules as the main basis for all of English syntax: 

S → NP  VP 
NP → (det)(adv)*(adj)*N
VP → V (NP) (ADV)*

So far, so good.  But while those phrase structure rules (sometimes called "re-write rules" because they allow you to "re-write" the parts of a sentence in ways that show their underlying grammatical functions) can describe thousands and thousands of English sentences, all of the sentences that these three rules can describe are still only a small part of the syntax you know as a speaker of English.  For English speakers don’t actually speak only “simple sentences” like “Jack eats raw meat,” or “The new student loves her trusty old iPhone.”  They also speak in “complex” sentences—sentences which become more capable of expressing our “complex” thoughts by including other sentences inside them.  This is a form of “recursion” in English—enabled by our ability to multiply meanings by a kind of mental recycling of structures.  Consider the following examples: 

  1. The children played in the yard and the dog ran around in the sun.
  2. The children thought that the dog was a cat
  3. The children who played musical instruments staged a concert.
  4. The children who played musical instruments staged a concert that delighted their parents.

Each of those is a normal and fairly common sort of sentence structure, but what is common to them all is that each has one or two sentences inside it as constituents.  [I’ve italicized the internal sentences (we also often call an internal sentence an “embedded” sentence) so you can see them clearly.]      

Thus in sentence 1 there are two embedded sentences, and they are connected by the conjunction “and.”  That is a “coordinated” construction, and one way to put sentences inside of another sentence (more on coordination in a moment). 

In the other three sentences the embedded sentences are actually “subordinated” to the main subject and verb.  That means that we have used an embedded sentence as a subordinate part of another.  Thus in Sentence 2 we have embedded the sentence:  the dog was a cat.  Here the embedded sentence functions as object of the verb “thought”.  Thus instead of a single noun to explain what the children thought (as in the sentence “The children thought things”), English also lets us use a whole sentence as if it were a noun.  For this we need one more Phrase Structure rule which says that in addition to being something describable by NP → (det)(adv)*(adj)*N an NP can also be (as it is in this example) a whole sentence:  NP → S. When we use this device we are in effect using a sentence as if it were the grammatical equivalent of a noun.

Traditionally an embedded sentence like this is called a “subordinate clause” because it is “ordered below ("sub")” the main sentence.  More technically, as the object of the verb, the sentence the dog was a cat is actually governed by the upper sentence’s main verb, and is thus its subordinate.  (Part III of our syntax will give you ways to draw pictures of these relationships, and will help make it more clear how they relate to each other.) 

In sentence 3 we also have another embedded sentence, but there the embedded sentence is “who played musical instruments”—where the pronoun “who” has been substituted for what would normally be the subject, “the children.”  The function of that embedded sentence is to modify “the children” by telling you which children were doing the staging.  This is called a relative clause because it offers information that relates information about the noun it modifies.

And sentence 4 has two embedded sentences, both relative clauses, one modifying children (just as in sentence 3) and one modifying concert, telling us what kind of concert it was—specifically: one that delighted parents.

We will give you phrase structures to account for these constructions in class, but once we have sorted them all out you will see that we manage to embed most sentences by structurally turning them into NPs.  We signal this with special words, like relative pronouns ("who," "which," "that") or with what we call “nominalizers” (of which English has three:  “that,” “for-to,” and also “<poss, -ing>”).
Finally, for this section, a word on coordinated sentences—like: 

  1. The children played in the yard and the dog ran around in the sun.

Here we have two sentences connected by “and.”  Neither one is grammatically subordinated to the other—instead they are what we call a “coordinated” sentence—where each member is equal to the other structurally.  That means that we could rewrite the sentence by inverting the two internal clauses (embedded sentences are traditionally called “clauses”) and they would mean pretty much the same thing:   

The dog ran around in the sun and the children played in the yard.

This turns out to be the OTHER basic phrase structure rule in English—a sentence is almost always made up of an NP and a VP, except when it is a coordinated sentence, in which case it is made up of two sentences along with a conjunction.  And we can represent that with the PS-rule:

                                                            S → S (c S)*

And that is the basic system.  We will work with those ideas in class—but to summarize what we have said above, all of our basic descriptions of English sentences can be represented with the following set of constituent structure rules: 

S → S (c S)*  (that’s for compound sentences)

S → NP VP  (that is for all sentences whether independent or dependent, main or embedded)

NP → (det)(adv)*(adj)*N  (that is for referring expressions)

NP → S  (that’s to account for the way we can use a whole sentence as if it were simply a noun phrase)

VP → V (NP)(ADV)*  (that’s for predicating expressions) 

Now, although that adds up to only five constituent structure rules (also referred to as “rewrite rules”) that’s a lot of stuff to take in—even though the goal, paradoxically, is to reduce the complexity of your knowledge of English to a relatively small number of rules. 



Example 1. Sally’s old man played the piano

This sentence has two main constituents: 

        NP                       VP
Sally’s old man / played the piano

So the whole sentence has the structure:  S → NP VP

The subject NP has three constituents:  two adjectivals (Sally’s and old) and one noun (man). 

(NOTE: “Sally’s” does not look like a traditional adjective, but its function here is to “modify” the noun “man” by describing which “man” we are talking about.  So we treat it here as an adjective.  (Sometimes instead of “adjective” linguists use the term “adjectival” to identify words that function as adjectives even when they are technically nouns.)

So the subject of Example 1 has the structure:  NP → adj adj N

The VP (played the piano) has two constituents:  a verb, and an object described by a noun phrase (played and the piano)

So it has the structure VP → V NP

The NP in the VP has two constituents:  a determiner and a noun

So it has the structure:  NP → det N  

Putting that altogether you have:

                        S → NP VP
                        NP → adj adj N
                        VP → V NP
                        NP → det N

Now, that's still a little complicated and mathematical-looking. So someone smart decided to invent "tree structures." We'll take that up in our next class session.




You know by now that any successful predication has both a referring expression—an NP—and a predicating expression—a VP. You also know that every NP has an N, and that every VP has a V.  You also know that we can include various things in NPs and VPs other than their basic N or V.  Among the largest group of such things to include are adverbs.  An adverb is a word, phrase or clause that modifies the verb (which means that it adjusts, or limits, or explains how, why, where, under what conditions, or for whose benefit [and a few other things] the action the verb denotes took place). 

The simplest of these to explain are the morphological adverbs—words like “quickly” or “homewards”.  In the sentence “He wrote quickly”, the adverb “quickly” modifies “wrote” by telling you something about how the writing was done.  In “She traveled homewards,” the adverb “homewards” modifies “travels” by telling you the direction in which the travelling occurred.  Here we just have a single word—the simplest way to modify a verb.

For "wrote quickly," or "traveled homewards", the underlying representation of the syntactic structure of the VP would be:  VP → V ADV. 

A second form of the adverbial function is the prepositional phrase (PP).  PPs are phrases of two or more words that, again, modify the verb by explaining how, why, where, for what reason, for whose benefit, in what direction [plus a few other things] the action the verb denotes took place. 

In short, a PP is just a kind of phrase that does the same thing as a single word adverb does.  So instead of saying “She travelled homewards” you could say “She travelled towards home,” where “towards” is a preposition and “home” is a noun.  All PPs have at least a preposition and an NP,  and that NP can take most of the shapes that any other NP can take.  So:

            He threw the ball over my head.
            He threw the ball over the girl’s head.
            He threw the ball over the very tall girl’s head.

All of those sentences have as a VP a V followed by an ADV, and that ADV has the structure of a PP, which is expressed by the rewrite rule:  PP → prep NP, where "prep" stands for preposition.

This means that ADV (which we will from here on call “the adverbial function” or an "adverbial") actually has more than one structural realization.  Sometimes it is a single word—something we call an “adverb,”.  And sometimes it is a prepositional phrase—something we call a PP.  But whether a morphological adverb (which we can shorten to “adv”) or a PP, the expression still has an adverbial function and is thus a form of the more general class ADV. 

We can represent this with a rewrite rule, and I have done that on your Mini-grammar. There you have a rewrite rule that includes the following: 

ADV →  adv

where adv and PP each represent a way of modifying verbs. 


So far, so good. And now for one last adverbial form. For in addition to these two kinds of adverbials, there is also a third very frequent way of modifying a verb, and that is with an entire sentence.  Consider the following: 

            She threw the ball because she seeks athletic glory. 

This third structure is more complicated than simple adverbs and PPs, but its function is exactly the same as the others, which means that it, too, is an adverbial.  Here, the clause “because she seeks athletic glory” answers the question “why” about the action denoted by the word “threw,” and the thing that causes listeners or readers to interpret that embedded sentence as an adverbial is the word “because”—one of a goodly number of “subordinating conjunctions”—or sub conjs.  Other such sub conj expressions are “since,” “after,” “before,” and “while”.   (For a list of other subordinating conjunctions click here, though the list at that site is rather old-fashioned and includes some connectives [like "that"] that would be treated differently in more technical circles). 

But to return to the more general point, each sentence embedded by using one of these (or a number of other) subordinating conjunctions has an adverbial function—even though it doesn’t actually look anything like an “adverb.”  It is just the third of three major ways of modifying a verb, and can be labelled (like the other two) as an “adverbial.”    

So our next ADV rewrite rule to add to Ye Newe Mini-Grammar is: 

ADV →  adv
               sub conj S

That would be pronounced: "Adverbial function [ADV] can be rewritten as either a morphological adverb [adv], a prepositional phrase [PP], or a subordinating conjunction followed by an embedded sentence [sub conj S]."

Finally, we'll add one more rule for adverbials--and that is Adverb Movement. This is used a great deal; here are three sentences that have undergone Adverb Movement:

On Friday, I finished my paper.

After I finished my paper I went for coffee.

Hesitantly, I stepped into the cave.

You will notice there are adverbials in all three of those sentences. There is just one in the first: "On Friday"; there are two in the second: the adverbial clause "After I finished my paper" and "the prepositional phrase "for coffee"; and there are also two in the third sentence: "Hesitantly" and "into the cave." What is different is that in each of the three sentences one of the adverbials has been moved to a different place in the sentence--separated from the verb it modifies. This is something we do a lot, and there are some rules that limit the places to which we can move any given adverbial. (We can't say "*I after I finished my paper went for coffee" and we can't say "*I stepped into hesitantly the cave."), but we can actually move adverbials to most positions in a sentence. Sometimes we will use a comma to set the adverbial off, but we don't have to do it in every sentence or syntactic location.

Why do we do it? Partially for variety in our sentence structures, but also for emphasis or even rhythmic reasons. But the thing to remember is simply that we do in fact move our adverbs around a lot but that moving them normally does not change their meaning. They are, as the term goes: "cognitively synonymous."

In any case, we must add to our rewrite rules: Adverb movement--an option that allows us to move an adverbial to different places in the sentence. It can apply to either of the three kinds of adverbials, and because it seeks the simplest and least stylistically modified form of the sentence, the tree diagram will show it in its most normal position in the VP--after the verb or the verb's direct object: ("I closed the door quietly").

[Those of you who have studied phonology should be able to see that ADV is to adv, PP, and sub conjS much as phonemes are to allophones or as morphemes like <past> are to different phonetic realizations depending on the verb used. Thus the most normal phonetic form of the past tense morpheme is <-ed>, but that "regular form" is quite different from what we use in the words "went," "hit," or "was." Looking or sounding differently doesn't always mean meaning differently. There are lots of things in language that are functionally equivalent but which take different surface forms. The wonder is that as users of a language we are able to deal with all the diversity of sound and form we encounter as we participate in the larger language community.]

Part IV: Relative Clauses

The last major creator of embeddings of one sentence within other sentences is the relative clause.

Consider the following sentences:

The man who circumnavigated the globe is my father.

The family that plays together stays together.

I met a couple who had travelled around the world.

The book that you read confused students who had not studied language philosophy.

In each of these sentences you will find embedded sentences (the italicized words), but none of them are subjects or objects of verbs nor are they ADVs. Every single one is a relative clause.

Relative clauses are sentences embedded to a noun, and not used to replace subject or object NPs or as adverbial constructions. Instead they are like full sentence adjectives, modifying the nouns with which they are paired. Look at the first example: The man who circumnavigated the globe is my father. I've italicized the relative clause (RC), and to see how it is a sentence just replace the relative pronoun "who" with the noun it stands in for: "the man". Logically, you are making a referring expression, and then adding some material to the sentence that explains more about the subject. So without the RC you would have the simple sentence "The man is my father." The difference between the example sentence and this stripped down version is that the first has more information about exactly WHICH man it is who is my father. Same thing in the second sentence: "that plays together" fills in information about which family you are referring to in the subject NP. Without it the sentence is largely nonsense: "The family stays together." Huh? What family? Well, the RC gives some additional information about which family you are talking about, and makes the sentence a good deal more understandable.

More study of relative clauses shows that they are closely related to adjectives. Thus the sentence "The man who was tall crossed the street" is cognitively synonymous with "The tall man crossed the street." In fact many linguists argue that relative clauses are really semantically equivalent with adjectives. Even a strange construction like "The circumnavigating-the-globe man is my father" can be processed, though I would grant it's pretty unusual. What is interesting is that in languages other than English something very much like this weird sentence is the norm, not the exception. (One such language is Chinese.)

Part V: Passive constructions

What is the Passive Voice?

Like many languages, English has both an Active and a Passive voice. This means that for many sentences, a writer can use one of two different forms, each of which has much the same meaning:

1. The student wrote the paper.

2. The paper was written by the student.

The first of these sentences is active, the second passive. The difference? Mainly a matter of emphasis. Because the first phrase of a sentence often seems to be the “focus” of a thought, the active form of this sentence gives emphasis to “The student,” while the passive form gives emphasis to “The paper.” Both forms are “correct,” both are "cognitively synonymous" (which means that they mean the same thing except for their changing of the primary focus of attention from agent to object), and both can be useful.

At the same time, many readers and writers have felt that passive constructions—especially in large numbers—are inherently less interesting to read than are active ones. Consider that most sentences have essentially three elements: first, a noun describing the “actor” involved in some action (in the sentences above, the actor is “The student”—the one who did something); second, a verb which describes what that actor does (here that’s “wrote”); and third, another noun describing the object of the action—the person or thing to which or upon which the action is performed (“the paper”—the thing that got written).

But if those are the three elements most important to describing most actions, many people have felt that writers should emphasize the actors of their sentences, because the agents of any given action have a special importance. Since active sentences put actors (also called “agents”) first, in the most emphatic position in the sentence, a decision to give emphasis to actors would require that you keep to active forms.

So active sentences tend to emphasize agents, and passive sentences tend to de-emphasize them. In addition, passives do two other things which many readers don’t like. First, they add words. Notice that sentence 2) above has two more words than 1). That’s because passives require both an auxiliary verb (“was” in this case) and a “by” to identify the agent phrase. And since more words with no extra meaning generally means more work for a reader's brain to do, the result (again) is less liveliness in the writing.

Second, passives allow a writer not only to change the primary focus of a sentence from the actor to the object, but also to drop one of the key elements—the actor—altogether. Note that sentence 2) above—The paper was written by the student—can be shortened by removing its last phrase: by the student. Take that phrase away, and even though the sentence now gives you less information, it still is perfectly proper English:

3. The paper was written.

(Notice that you can’t remove the actor from the active form shown in sentence 1: “John wrote the paper” is a complete thought; “Wrote the paper” is not—it makes no sense by itself.)

And so what? As already suggested, to describe any event to someone, you can give various kinds of information, but the three most central elements are usually the actor (the one who does something), the object (the thing being acted upon), and the verb (the action taken). When you leave one of this Big Three out, you also leave a sort of logical hole in your description. In the passive sentence "The paper was written," the author of the sentence has left out one of the Big Three: the actor, or who it was that did the writing.

To be sure, as readers we will assume that “someone” did the writing—it could hardly happen by itself alone! But an unexpressed “someone” is a whole lot less specific, and thus less lively, than a more definite description. Of course, if the author didn’t know who did the writing, then she or he couldn’t have supplied an actor in the first place, and maybe that’s the reason for the passive. But often we DO know who the actor was, and yet we use a passive without an actor anyway and thereby avoid giving readers an important part of the picture. We can do that either because we don't care who did whatever it was that the sentence predicates ("The car was bought ten years ago" is a sentence where few will be interested in who did the buying), or we don't know (OMG! My watch has been stolen!), or we can easily surmised who did it ("You have been charged with grand larceny"), or we don't want to say ("You have been fired.").

In sum, passives can lead to less lively, more difficult to read writing for three reasons: first, because a passive construction may make the sense of a sentence less vivid by moving the actor away from its normal, emphatic position; second, because it adds unnecessary words; and third, because it may even lead you to drop out any mention of the actor altogether.

Should you then never use the passive voice? Some teachers have said so, but that seems pretty drastic. What happens when in fact you don’t want to emphasize the actor, but the object instead? At that point the passive may be the best choice. So rather than avoiding the passive altogether, a better rule would suggest that writers should first learn to recognize passives, and then choose to retain them as passive constructions only when it’s clear that an active form would somehow not work as well or better. If you have a good reason to use the passive, then do it. If you don’t, use the active.

Finally, a last observation is that neuro-linguists have studied the length of time people take to process active vs. passive constructions and have found that people generally take a few milliseconds longer to process a passive construction that to process an active construction. That is evidence for the active form's being the basic form and the passive form's being a derivitive of the active.

How We Represent the Passive form of Sentences

With all of that said, how do we represent passives in a tree diagram? We treat them (as I wrote in the preceding paragraph) as being derived from the more standard "active" form of a sentence. Take a simple example: The telephone was invented by Bell. That is a passive construction of the active sentence: Bell invented the telephone. It was formed using three steps:

1. Insertion of the passive auxiliary (be),

2. Insertion of the agent marker "by," and

3. Inversion of the active NP with the active Object NP.

So in the sentence "Bell invented the telephone," "Bell" is the active NP, "the telephone" is the active Object NP, and the verb (obviously!) is "invented." And when we have taken the three steps of the passive formation listed above, we get the sentence: "The telephone was invented by Bell."

You can easily see that the NP's have been inverted; you can also see that the verb in the active form "invented" has been changed to "was invented"—which involves adding a form of the verb "to be" (which our language processing brain recognizes as a marker of the passive) —and you can see as well the added "by"—an agent marker to make sure we know who did the inventing. In short, "Bell invented the telephone" becomes "The telephone was invented by Bell."

In semantic terms the two sentences mean exactly the same thing, and for that reason linguists say of the two sentences that they are "cognitively synonymous"—which is why we use just one deep/logical structure for both the active and the passive forms. We may transform one way of ordering the sentence into another way, but we haven't changed its basic meaning, only altered our primary focus from the agent to the object.


And there you are—the primary issues of syntax we will be dealing with in this course. There is much more we could include had we time enough, but this is enough to be able to describe a huge range of styles, and that, after all, is our primary concern .