5.8: Trees- Sentences as TPs

So far we’ve applied X-bar theory to a range of phrase types. But what about sentences? Up to this point we’ve simply been labelling them as “S”, as in Figure 6.10.

Figure 6.10 Tree diagram for The robot repaired a spaceship. (to be revised)

But if a “phrase” is a string of words that form a constituent, then sentences are also phrases—and X-bar theory requires that all phrases have heads, a hypothesis we don’t want to abandon unless we have evidence that it’s incorrect.

What could the head of the sentence be?

Recall that we had a phrase structure rule for sentences like the following:

• S –> NP (Aux) VP

This rule allows sentences to include an auxiliary between the subject NP and the predicate VP, as in Figure 6.11:

Figure 6.11 Tree diagram for The robot will repair a spaceship. (to be revised)

This tree has two problems from the perspective of X-bar theory: now not only does the sentence (S) not have a head, but the auxiliary is a head without a phrase! We could simply put the Aux into an AuxP, as we did with determiners, degree adverbs, and so on. But there’s another option open to us: we can solve both the lack of a phrase for Aux and the lack of a head for S in one stroke, by analyzing the auxiliary itself as the head of the phrase:

Figure 6.12 Tree diagram for The robot will repair a spaceship., with the sentence as category AuxP (to be revised)

What if there weren’t an auxiliary, though? Are all sentences AuxPs? No. In fact, if we think about what auxiliaries in English express, they are always inflected for tense. Even in the absence of an auxiliary, we see tense on the main verb, and in nonfinite clauses the nonfinite marker to takes the place of an auxiliary.

Based on this, the proposal in X-bar theory is that sentences aren’t auxiliary phrases, but they are tense phrases (TPs). Tense represents finiteness—we say that sentences when they stand independently are always finite, which is a term meaning that they have tense.

This is an example of a case where the greater technical detail of X-bar theory motivates us to look at sentences and reconsider whether they are projections of some category, just like all other phrases are. In fact, TP is a very nice phrase from the perspective of X-bar theory, because it always has both a specifier (the subject) and a complement (the predicate).

What things are of category T?

• The modal auxiliaries (will, would, can, could, may, might, shall, should, must)
• The non-modal auxiliaries (be, have, do)
• The nonfinite marker to
• Abstract tense features ([+PAST] for past tense, [–PAST] for present tense)

So the final version of the tree for The robot will repair the spaceship. is as in Figure 6.13, and the final version of the tree for The robot repaired the spaceship. (without an auxiliary) is as in Figure 6.14.

Figure 6.13 Tree diagram for The robot will repair a spaceship., with the sentence as category TP (final version)

Figure 6.14 Tree diagram for The robot repaired a spaceship., with the sentence as category TP (final version)

What about languages that don’t have tense?

There are different options! We could say that languages that don’t require tense—like Mandarin or Cantonese, for example—don’t have sentences that are TPs, but instead have some other category. (Can you think of any plasible options?)

The other option is to assume that even though we don’t pronounce tense in all languages, it’s nonetheless the case that something abstract makes a sentence a sentence—something that corresponds to “finiteness”. So even if it doesn’t have the same meaning as English tense, there’s something that does the same grammatical work of anchoring a clause, and gluing the subject and predicate together.

This second option is fairly widely assumed, in the type of syntactic theory that we’re learning in this class (descendants of X-bar theory). People sometimes use the label “Inflection Phrase” (InflP or IP), but it’s also common to simply use the label “TP” even if you’re assuming that the semantic content of this functional phrase might vary.

X-bar theory and language variation: Head direction

We saw in Section 6.3 that languages can vary systematically in their basic word order, and characterized some differences in terms of the relative order of heads and their complements.

This analysis is very easy to encode in X-bar theory, by a simple switch in the X-bar template of languages of the two types.

Recall the basic shape of phrases of several categories in English, illustrated in the trees in Figure 6.15.

(1)	a.	I [VP ateV [NP an apple ].
	b.	[PP toP [NP Toronto ]
	c.	[NP pictureN [PP of a robot ]

Figure 6.15 Tree diagrams showing head initial word order in English

In contrast to English, Japanese is a strictly SOV language. And in Japanese, heads always follow their complements, the reverse of the order we get in English.

What X-bar theory allows us to say is that phrases in Japanese have the
same structure as phrases in English, but a different order.

Specifically, in Japanese complements are still the siblings of their heads, but they precede the head instead of following it, as illustrated for the examples in (2) in Figure 6.16. These Japanese examples appeared previously in 6.3 Structure within the sentence: Phrases, heads, and selection.

(2)	a.	Watasi-wa	[VP	[NP	ringo-o	]	tabe-ta.	]
		I-TOPIC			apple-ACC		eat-PAST
		“I ate (an) apple.”
	b.	[PP	[NP	Tokyo	]	e	]
				Tokyo		to
		“to Tokyo”
	c.	[NP	[PP	robotto	no	]	shasin	]
				robot	of		picture
		“picture of (a) robot”

Figure 6.16 Tree diagrams illustrating head final word order in JapaneseIf we draw a tree for Japanese, we would extend this template to TP, as well as all the other phrases we’ve looked at, as shown in Figure 6.17.

Figure 6.17 Tree diagram showing a head-final TP structure in Japanese

When you’re drawing a tree for another language, it’s important that the words come in the right order if you read the words off the bottom of the tree! If you’re analyzing an unfamiliar language, and need to figure out its word order, one of the first questions you should ask is whether it appears to be head initial or head final.

In contrast to complements contrast, specifiers don’t show the same variation. They always come before their complements, across all known languages.

When analyzing a new language, the starting assumption is that all structural relations are the same, but that linear order and the distribution of silent functional heads may be different. Beginning in Section 6.19, we will also see the possibility that languages may exhibit different types of movement.

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If you are following the alternative path through the chapter that interleaves core concepts with tree structures, the previous section was 6.14 Trees: Introducing X-Bar theory, and the next section is 6.16 Trees: Modifiers as adjuncts.

6.16: Trees- Modifiers as adjuncts

When we introduced X-Bar theory, we gained the ability to represent the asymmetric relationship between heads and their complements on the one hand, and heads and their specifiers on the other hand.

At the same time, with X-Bar structure as we’ve had it so far, we lost a bit of empirical coverage that we’d been able to include in phrase structure rules: we lost a place to put modifiers:

• AdjPs and NumPs in NPs
• AdvPs in VPs and TPs
• modifier PP in all other phrases

With adjuncts we expand X-Bar structure to accommodate modifiers.

The basic idea of adjuncts is that while there can only be one head in a phrase, and there can only be one phrase (because it’s the final projection of a head), a bar level is a “mid-sized phrase” or “partial phrase”, and in principle there can be many partial phrases within a larger phrase.

Let’s see how this works in practice. Consider the noun phrase (NP) in (1).

(1)

[NP the early arrival of spring ]

This NP contains a modifying adjective phrase [_AdjP early ]. Without that AdjP, the structure would be as shown in Figure 6.18.

Figure 6.18 Tree diagram for [the arrival of spring], showing that both Specifier and Complement positions are occupied.

In this NP both the specifier and complement positions are filled, so there’s no more space for the adjective phrase [_AdjP early ].

By adding additional bar levels, we can create structural “space” for modifiers. These positions are neither specifiers nor complements, instead they are adjuncts.

Adjunct

A constituent that is both the child and sibling of X’ is an adjunct.

Unlike specifiers and complements, adjuncts are flexible in their position: they can appear on either the left side or the right size of a phrase structure.

Figure 6.19 illustrates how an additional N’ creates space for [_AdjP early ] to appear as an adjunct.

Figure 6.19 Tree diagram showing [_AdjP early] as an Adjunct to N’, with the extra N’ level creating “space” for the modifier.

The same expansion of X-Bar structure gives us space within an NP to represent two PPs after the head noun, as in [_NP a letter [_PP from home ] [_PP in the mailbox ] ]. If we run our one-replacement test, we can show that letter can be replaced by one, leaving either both PPs behind, or leaving just the second one behind. If one replaces an N-bar constituent, this means that there must be an N-bar that contains letter but not either of the PPs.

(2)	a.	I saw a letter from home in the mailbox, and one from the bank on the table.
	b.	I found that letter from home in the mailbox, and this one on the table.

The tree showing both PPs as adjuncts within NP appears in Figure 6.20.

Figure 6.20 Tree diagram for [ the letter [PP from home] [PP in the mailbox], showing both PPs as Adjuncts.

Adverbs within verb phrases are also adjuncts. We’ve already seen that adverbs can go either at the beginning or end of verb phrase, as in (3a-b); we can also get more than one adverb in a verb phrase, as in (3c).

(3)	a.	They [VP [AdvP quickly] left the room]
	b.	They [VP left the room [AdvP quickly]].
	c.	We [VP [AdvP deliberately] left the room [AdvP slowly]].

Adverbs appearing in adjunct positions to the left and right of VP are shown in Figure 6.21.

Figure 6.21 Tree diagram for [VP [AdvP deliberately] left the room [AdvP slowly]], showing both adverbs as Adjuncts to V’.

All adverbs occur in adjunct positions, as do all adjective phrase inside NP. (Predicate adjectives, as in The book is long. are complements of a verb.)

PPs sometimes occur as complements, and sometimes as adjuncts—we’ve seen examples of both in this section. constituency tests like replacement with one (for N’) and do so (for V’) are very useful for figuring out if a particular PP is a complement or an adjunct.

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If you are following the alternative path through this chapter that interleaves core concepts with tree structures, the previous section was 6.15 Trees: Sentences as TPs and the next section is 6.17 Trees: Structural ambiguity.

6.17: Trees- Structural ambiguity

In Section 5.9 we saw cases of structural ambiguity in morphology, cases where the same string of morphemes can have more than one structure, with each structure corresponding to a different interpretation.

The same thing is found in syntax. Consider the following example:

(1)

I saw someone with a telescope.

This has two possible interpretations:

1. I was using a telescope, and I saw someone. (PP modifies VP)
2. I saw someone, and that person had a telescope. (PP modifies NP)

In the first interpretation, the prepositional phrase [_PP with a telescope] modifies the verb phrase headed by saw. In the second interpretation, the same prepositional phrase modifies the noun phrase someone. These two structures are illustrated below:

Figure 6.22: Tree diagram showing [_PP with a telescope] as an Adjunct of the verb, meaning “I used a telescope to see someone”.

Figure 6.23: Tree diagram showing [_PP with a telescope] as an Adjunct of the NP object, meaning “I saw a person and that person had a telescope”

The same will be true for other cases of structural ambiguity—each meaning will correspond to a different potential tree structure.

Many cases of structural ambiguity in syntax involve modifiers in adjunct positions on one or both interpretations. Some of the practical implications of ambiguity are discussed in 8.3 Semantics and pragmatics in the legal domain.

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If you are following the alternative path through this chapter that interleaves core concepts with tree structures, the previous section was 6.16 Trees: Modifiers as adjuncts and the next section is 6.6 Clausal embedding.