Syntactic valency

Phrase structure rules like those introduced in Section 7.4 are very useful in describing the way that words are combined into larger units in a given language. However, they are not by themselves sufficient: we can very easily construct sentences that follow these rules but that are nevertheless not possible in English.

Take a look at the following examples:

These are all possible sentences of English, which is expected, given that they all follow the phrase-structure rule for VPs that we introduced in the preceding section:

The verb phrase in (1a) consists of a verb without any of the optional phrases, the one in (1b) makes use of the option to include an NP, and the one in (1c) includes a second NP in addition.

So, why are the following sentences not possible? After all, they also follow the rule in (2) — in fact, they have the same structures as the sentences in (1):

We could argue that they are, in fact, possible but that, for various reasons, they simply don’t make sense. The sentence in (3a), for example, omits important information — it does not mention what Noah handed to whom. Conversely, the sentence in (3b) contains too much information — stumbling is something a person does by themselves, it does not involve another person.

However, these arguments quickly run into problems. Consider the following sentences:

The sentence in (4a) also omits important information — it does not mention what Aylin drank. Nevertheless, it is a possible, perfectly normal sentence of English. When we hear (4a), we know that Aylin must have drunk something, but we accept the omission and assume that the omitted information is not important. In the same way, when we hear (3a), we know that Noah must have handed something to someone, so why do we not accept this omission, even in a situation where the omitted information is not important? The sentence in (4b) contains too much information — walking is something that a person does by themselves, it does not involve a second person. Yet, we accept (4b) and interpret it to mean that Noah accompanied Aylin home and that both of them walked. So why do we not accept (3b) and interpret it to mean that Aylin and Noah stumbled together, or that Aylin caused Noah to stumble?

Verbs simply differ with respect to the number of constituents that they can or must be used with. The meaning of the verb does not allow us to predict this number. Verbs also differ with respect to the type of constituent that they can or must be used with. For example, spill must be used with a noun phrase referring to a substance that is spilled (for example, the water), and it can be used with an additional prepositional phrase containing a noun phrase that refers to the location that this substance ends up in (for example, on the floor). This is how it is used in (1b). The location cannot be expressed using a noun phrase instead, as in (3c).

The requirements of a verb concerning the number and type of constituents that it can or must be used with is called its syntactic valency (or sometimes its subcategorization). There are some types of valency that are so frequent that they have their own labels — verbs that do not require or allow any constituents (other than the subject), like stumble, are called intransitive, verbs that require one noun phrase (in addition to the subject), like spill, are called transitive, and verbs that require two noun phrases are called ditransitive. However, there are additional kinds of verbs — for example, verbs that require or allow a specific prepositional phrase, like look for, or verbs that require a noun phrase and a prepositional phrase, like put (Zoe put her phone in her pocket).

It is therefore more useful to represent the valency of a verb by listing the number and type of phrase that it requires or allows. Before we try this, there are two issues to be discussed. The first is whether the subject should be included in such a list. Some linguists say this is unnecessary, at least in English, because all English sentences have a subject, so that nothing would be gained by including it. However, while all sentences require subjects, not all verbs do. For example, many weather verbs (like rain, snow, thunder, etc.) do not require subjects, so when we use them in a sentence, we have to insert a meaningless it in the subject position:

So it is best to include the subject (we will discuss another reason later).

Second, we have to distinguish between phrases that must occur with a particular verb and phrases that can occur with a particular verb — as we saw in the case of spill, it has to have a subject and one additional noun phrase referring to the material that is spilled, and it can have a prepositional phrase referring to the final location of that material. Phrases that have to be used with a particular verb are called its obligatory complements. Phrases that can be used with a particular verb are called its optional complements. These differ from phrases that can be used with any verb — these are called adjuncts. The following sentences illustrates the difference between optional complements and adjuncts:

On Monday and in Paris are adjuncts, as we could add them to any verb. You can see this by adding them to every single example sentence in this book — you will always get a possible (grammatical) sentence! Here are some examples:

In contrast, for her sunglasses and over his notebook are optional complements, as we can not add them to any verb. Again, try to add them to some example sentences from this book — this will not be possible most of the time. Again, here are some examples:

Optional complements must be included in valency descriptions, as they are specific to particular verbs, while adjuncts are, obviously, not included. Let us represent the valency of verbs as follows:

• rain: [ __ ]

• stumble: [ NP __ ]

• walk: [ NP __ ]

• drink: [ NP __ (NP) ]

• watch: [ NP __ NP ]

• see: [ NP __ NP ]

• like: [ NP __ NP ]

• hand: [ NP __ NP NP ]

• spill: [ NP __ NP (PP) ]

• look: [ NP __ ([_PP for NP]) ]

• put: [ NP __ NP PP ]

The underscore indicates the position of the verb in an active sentence, so that we can distinguish the subject, which is not part of the verb phrase, from the other complements, which are part of the verb phrase. Parentheses indicate optional complements (for example for drink). Where a PP has to contain a specific preposition, we represent it in the form of a bracketing structure, as introduced in Section 7.3 (for example, for look).

Semantic valency

Specifying the number and syntactic type of a verb’s complements allows us to explain why the sentences in (3) above are ungrammatical: while their verb phrases follow the phrase-structure rule for VPs in English, they do so in a way that ignore the valency of the specific verbs in these verb phrases.

Now look at the following sentences:

These sentences follow the phrase structure rule for English VPs and they have the right number and type of complements, but there is still something wrong with them. They are not exactly ungrammatical, but they are not possible sentences of English either (this is indicated by the question marks preceding them).

The problem is that some of the complements have the wrong meaning. The verb put does not just require a PP, it requires a PP that describes a location; however, the PP in (9a) describes a point in time. The verb hand does not just require three NPs, it requires one of these NPs to describe someone who carries out the action, one of them a person who receives something, and one of them an entity that changes location. In example (9b) the second NP refers to a location instead of a recipient. And the verb watch requires a living being capable of visual perception and a visible entity. Example (9b) has both, but they are in the wrong place.

As users of a language, we not only know the number and syntactic type of complements that a verb requires or allows, but we also know the general semantic type that these complements must have. These general semantic types are called semantic roles and the specific combination of semantic roles that a verb requires or allows is called its semantic valency.

It is difficult to determine exactly how many semantic roles there are in a given language and exactly how they should be characterized, since this depends largely on how specific or general we want to make their description. At the most specific level, every verb has a set of very specific semantic roles that may be unique to it or that it may share with only a handful of other verbs. For example, the verb sleep has one semantic role — ‘sleeper’ — that it shares with no other verb, and the verb buy has three semantic roles — ‘buyer’, ‘seller’ and ‘goods’ —, that it shares with a few other verbs (mainly, the verb sell). Such specific semantic roles would do the job of ruling out sentences like those in (9), but they do not allow us to make general statements, for example, about classes of verbs with a similar semantic valency (which we will need to do in a moment), or in order to describe the interaction of semantic roles with grammatical relations like subject and object (which we need to do in the next section).

You will encounter slightly different lists of more general semantic roles, but the following are fairly wide-spread and have proven themselves to be useful:

1. Agent — someone who carries out the action described by the verb deliberately or accidentally (e.g. Aylin baked bagels, Noah spilled water, Aylin lost her papers);

2. Force — something causes the process or action described by the verb but that is not volitional and cannot act with deliberation (e.g. The thunderstorm felled the tree);

3. Instrument — something used by an Agent in order to carry out the action (e.g. Aylin rolled the sushi with a rolling mat);

4. Patient — someone or something that undergoes a change of state or comes into existence as a result of the action or process described by the verb (e.g. Aylin baked bagels, The thunderstorm felled the tree);

5. Theme — someone or something that (a) exists in the state described by the verb (e.g. Zoe slept all day), (b) is part of the process or action described by the verb but does not change state (e.g. Zoe watched a documentary), or (c) changes location as a result of the action or process described by the verb (e.g. Aylin lost her papers, Noah spilled the water);

6. Recipient — someone who receives something as a result of an action (e.g. Noah handed Aylin a glass of water); sometimes, this is included in the more general role Beneficiary — someone who benefits from an action (e.g. Zoe downloaded the documentary for Aylin);

7. Experiencer — someone who perceives, thinks or feels something (e.g. Zoe saw the tree, Noah believes in aliens, Zoe likes Aylin);

8. Stimulus — something that prompts or is the content of a perception, thought or feeling (e.g. Zoe saw the tree, Noah believes in aliens, Zoe likes Aylin);

9. Location — a place where the action occurs (e.g. Zoe watched a documentary in the cafeteria, sometimes split up into subcategories like Source (e.g. Noah got off the tram) and Goal (e.g. Noah spilled the water on the floor);

10. Time — the point or period of time at or during which the state, process or action described by the verb occurs (e.g. Zoe looked for her sunglasses on Monday, It rained all week);

11. Manner — the way in which the state, process or action described by the verb occurs (e.g. Noah talked about aliens at great length).

Using these semantic roles, we can now describe the valency of our verbs more precisely:

• rain: [ ___ ]

• stumble: [ NP_Theme ___ ]

• walk: [ NP_Agent ___ ]

• drink: [ NP_Agent ___ (NP_Patient) ]

• watch: [ NP_Agent ___ NP_Theme ]

• see: [ NP_Experiencer ___ NP_Stimulus ]

• like: [ NP_Experiencer ___ NP_Stimulus ]

• hand: [ NP_Agent ___ NP_Recipient NP_Theme ]

• spill: [ NP_Agent ___ NP_Theme (PP_Location) ]

• look: [ NP_Agent ___ ([_PP for NP_Theme]) ]

• put: [ NP_Agent ___ NP_Theme PP_Location ]

You can now see a second reason for including the subject in the valency description: subjects, too, have different semantic roles depending on the verb, and by including them, we can specify this role. Such lists of complement types with semantic roles are often called valency patterns, when we want to talk about them independently of a specific verb. For example, we might want to say that see and like have the same valency pattern, so they form a class.

Valency change

As the following examples show, a verb can have more than one valency pattern:

There are four valency patterns here:

• search: [ NP_Agent __ NP_Location ([_PP for NP_Theme]) ] (see 10a)

• search: [ NP_Agent __  [_PP for NP_Theme] ] (see 10b)

• search: [ NP_Agent __ PP_Location [_PP for NP_Theme] ] (see 10c)

• search: [ NP_Agent __  [_PP after NP_Theme] ]  (see 10d)

This combination of valency patterns is unique to search — each of the valency patterns also occurs with other verbs, but no other verb has all four patterns. Some examples are shown in Table 7.5.1

Table 7.5.1: Four valency patterns

	examine	rummage	seek	check
[ NPAgent __ NPLocation ([PP for NPTheme]) ]	✓	✗	✗	✓
[ NPAgent __  [PP for NPTheme] ]	✗	✓	✗	✓
[ NPAgent __ PPLocation [PP for NPTheme] ]	✗	✓	✗	✗
[ NPAgent __  [PP after NPTheme] ]	✗	✗	✓	✗

Generally, we therefore have to figure out the valency patterns for every verb individually. Linguists, who like making general observations about language, are often not very interested in this kind of work, leaving it to lexicographers.

But linguists are very interested in cases like the following:

Each of the verbs in (11) has two valency patterns, the one in (12a) and the one in (12b):

What makes this case different from the one in (10) is that we can make several generalizations: first, there is more than one verb that has these two valency patterns; second all verbs in (11) are verbs describing a change of state; and third, there is a systematic meaning relation between the two valency patterns — the one in (12b) always means ‘Patient changes’, the one in (12a) always means ‘Agent causes Patient to change’.

Such cases are known as valency alternations (or argument-structure alternations, where argument structure is just a different term for valency). They are sometimes represented as lexical rules, which are similar to word-formation rules for zero derivation, except that they do not change the word class of a word, but the valency. The alternation in (11) could be represented as follows (a very simplified version of the representations you will encounter in the research literature):

 

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