25 Empty Category

Ms. Muskaan

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Learning outcome

This module deals with different types of nominal elements and their relevance in the study of Syntax in general and empty categories in particular. Different types of empty categories namely, big PRO, small Pro and traces will also be discussed. Multiple-choice questions and other self-assessment exercises along with answers will be provided at the end of the module for easing the assessment of better knowledge and understanding of the work. In order to understand various aspects of the module examples, tables and tree diagrams will be provided with detailed explanations. Bibliography and list of websites related with the module will provide base for further understanding and readings.

Introduction

Some of the important concerns of Linguistics has been to understand why languages behave the way they do and why something which is obligatory in one language becomes optional for the other. Various frameworks have evolved within generative linguistics as a measure to deal with these queries, principles and parameters framework being one of them. It was proposed by Noam Chomsky and is also known as Government and Binding theory. Principles and parameters is explained in Chomsky’s (1981) book Lectures on Government and Binding, in terms of a finite set of principles which are fundamental and therefore obligatory to all languages and a finite set of non-obligatory parameters which are optional are therefore result in variations in languages. An example of such a fundamental principle can be the Extended Projection Principle, which makes the presence of a subject obligatory for every clause, in all the languages, even if it is not phonetically pronounced or overtly present. However, whether a language has subject that is overtly present and phonetically pronounced or not, is a matter of parametric variations. It is known as pro-drop parameter. Pro-drop parameter can be understood with more clarity in terms of pro-drop languages, which will be explained later as we proceed.

While dealing with cross-linguistic variations and linguistic relativity, Whorf (1956) came up with an important concept, which distinguished, between the overt and covert nature of grammatical categories. Any feature of a word or phrase is said to be overt if it explicitly exists at the surface i.e. if it morphologically marked and has a phonetic form. On contrary to this, if a feature is morphologically unmarked but is rather implicitly present then is said to be covert in nature. The presence and meaning of a covert feature can be understood from the context of the discourse. English has covert gender, for example; in a sentence like,

1) My professor asked me to write a letter.

Here, the gender of the professor cannot be guessed unless a personal pronoun is used in the sentence. So if we have another sentence,

2) My professor asked me to write a letter for her.

Here the gender of the professor as a female becomes clear as indicated by the use of her.

In other languages like Spanish, gender is overtly marked at the end of a noun. If we talk about the syntax of noun phrases we see that they are highly complex and have always been a topic of research. Apart from a certain features like gender or number, the overt and covert distinction applies to the whole NP itself. So, NPs that can be pronounced are overt NPs and covert NPs are NPs that cannot be pronounced because they do not have morphological and phonological content. Such covert NPs are often called empty categories, a term given by Chomsky.

Duranti (2001) claimed that it is Whorf’s overt and covert distinction that provided the foundations on which Chomsky’s (1965) distinction of deep structure and surface structure is based. Deep structure is the underlying form, which accounts for the semantic component and meaning while surface structure accounts for the phonological component and sound. Deep structure is turned into surface structure via transformation rules. Later on with advancements in Syntax, D-structure and S-structure were  used instead of the former terms in the Government and Binding theory (henceforth GB theory). these terms were again replaced by LF (logical form) and PF (phonological form). Since we are dealing with empty category, which forms a part of GB theory, we will be concerned with D-structure and S- structure and their interactions with relevance to empty categories. D-structure is generated by lexical insertions into the delta-nodes, which are lexical placeholders via phrase structure rules. These lexical placeholders are phonologically and semantically null. Lexical categories like noun, verb, adjective etc. are heads and a head selects its components to form a phrase. Verb chooses its complement through sub categorization requirements. This choice of complement, determined by the Projection Principle (1986), claims that syntactic structures are determined by lexical information. The thematic roles (agent, patient, goal, theme and others) and subcategorization requirements are interpreted and met at the D-structure. Move-α forms the transformational component and maps D-structure to S- structure. Move-α means movement of elements in a sentence from one syntactic position to another leaving behind trace, an empty category. Other empty categories include big PRO and small Pro.

In order to understand more about empty categories that are covert NPs, it becomes prerequisite to have some idea about overt NPs. Overt NPs are of three types; anaphor, pronominal and referential expression. These NPs behave distinctively in syntactic structures and form the basis of one of the most important modules of Government and Binding theory namely, the Binding theory. Let’s discuss these NPs and the way they are interpreted in detail. Anaphors are of two types, reflexives like  herself, myself etc. and reciprocals like each other, one another etc. Another NP mentioned in the sentence can only determine interpretation of both these anaphors. Interpretation of pronouns like he, her, it etc. may or may not depend upon referents from within the sentence but it does not select a referent from the universe of discourse either. R-expressions like John, Peter etc. are interpreted based on the referents from the universe of discourse. Now we will move forward to binding theory;

Binding Theory

Binding theory is another module of GB. It is responsible for regulating the referential features of overt NPs. It consists of three principles that deals with the binding properties of an anaphor, pronominal and referential expression. These principles are as follows;

  • Principle A: An anaphor should be bound in its governing category.
  • Principle B: A pronominal should be free in its governing category.
  • Principle C: An R-expressions must be free everywhere.

Two entities are given same index through the process of co-indexation. It is actually a way of making sure that two NPs have a common referent. An antecedent is an NP that provides its interpretation or meaning to the other NP with which it is co-indexed. For example; in a sentence,

3) Sitaᵢ loves herselfᵢ.

Here, we see that Sita is co-indexed with herself. Herself is a reflexive anaphor and Sita is its antecedent.

 Let’s see some other examples of binding theory at work;

4) *Sitaᵢ loves herᵢ. (co-indexation suggests that the indicated reading of Sita loving herself is impossible)

5) Sitaᵢ told Radhaᵣ that sheᵢ loves herᵣ. (co-indexation of Radha with her suggests that the indicated reading of Sita loving Radha is possible)

Empty Category

In a layman’s term, empty categories can be defined as NPs that are not overtly present in a sentence. However this definition needs to be explained beyond the mere presence or absence of the entity in question. Let’s first focus on why there is a need to discuss empty categories. English, like other languages, has complex sentences and the theoretical advancements in the syntactic theories related with the study of complex sentences postulate that complex sentences permit movement rules in order to map the underlying representation to its surface representation. This movement rule is called move- α which literally means move anything anywhere. However one of the most noticeable consequences of permitting movement rules in syntax is the occurrence of empty categories, namely trace.

Empty categories exist as a result of one of the two factors. They can either be base generated or  occur as a result of movement of elements from one syntactic position to the other in a syntactic structure. So, we see that on the basis of the way they are generated empty categories are of two types, base generated and movement generated. Base generated empty categories are Big PRO (PRO) and small pro (pro). NP-traces and Wh-traces are two of the movement generated empty categories. Empty category is used as a cover term for these four categories. An important feature of these covert NPs is their resemblance to specific overt NPs in terms of their behavioral features. Though they are not overtly present, they do share certain features. Pro behaves in the same way as pronominal. NP- trace and anaphor share common behavioral features and wh-trace and R-expression have similar features too. So, we can classify the overt and covert NPs on the basis of their behavioral features in a table;

Types Overt NPs Non-overt NPs
[+ anaphoric, + pronominal] PRO
[- anaphoric, + pronominal] Pronominal pro
[+ anaphoric, – pronominal] Anaphor NP-trace
[- anaphoric, – pronominal] R-expression Wh-trace

In the table given above, we see that except PRO every other non-overt NP or empty category has an overt counterpart. Another point to note is that it is both anaphoric as well as pronominal in nature which is very interesting. We will focus on it later as we proceed after defining Big PRO in the following section that deals with all four types of empty categories in detail.

Types of Empty Category

Big PRO (PRO)

 

The concept of Big PRO was given with reference to one of the modules of GB theory, namely Control theory. PRO is an empty category that is not phonetically realized and forms the null pronoun subject of nonfinite clauses. Control theory is a module of GB that deals with the PRO and establishes a link between PRO and its antecedent, where an antecedent is an element that provides its meaning to a pro-form i.e. PRO. Certain concepts which are relevant for a better understanding of PRO are Extended Projection principle, Theta theory, theta- criterion (θ-criterion), nonfinite clauses, Control theory, Binding theory, etc. These separate linguistic theories work together to motivate the existence of PRO and other empty categories too in one way or the other. Let’s start with theta theory.

Theta Theory:

 

Theta theory is a module of GB theory that deals with the assignment of theta roles to the arguments in a sentence. Theta roles are semantic roles that represent syntactic argument structure required by a specific verb. Agent, patient, goal, theme, experiencer, recipient, instrument etc. are certain types of theta roles. An argument of a verb is assigned agent theta role if it deliberately performs the action described by the verb and the argument acted upon by the agent carries patient theta role. Recipient theta role is assigned to an argument that receives something. Goal theta role is assigned to the argument that describes the goal or the main point of action described by the verb. Experiencer theta role is assigned to an argument of verb which does not reflect a deliberate action and the argument acted upon by the experiencer carries theme theta role. Both external and internal theta roles are assigned via. Sisterhood condition and theta criterion. Sisterhood condition states that theta roles are assigned to the sisters of the assigning elements. Complement being the sister of head helps in internal theta role assignment and external theta role is assigned by V-bar as a result of VP internal subject hypothesis that states that subject actually generates at the specifier position of VP and then moves to the specifier position of IP, thereby making the subject a sister of V-bar. For example;

 

6) John punched

 

Agent     patient

 

7) My grandmother saw a flower

 

Experiencer      theme

 

Theta criterion is another basic principle of theta theory according to which theta roles are assigned to only one argument and arguments can bear only one theta role.

Extended Projection Principle

 

The concept of EPP was proposed by Chomsky as an extension or advancement of Projection Principle. EPP states that every clause must have a subject. Certain verbs require semantic and meaningful subjects while others don’t. See for example;

8) Mohan played

Here, a verb like play requires a meaningful subject Mohan. However in a sentence like;

9) It rains.

It is an expletive or a pleonastic subject that is not assigned any external theta roles by an intransitive verb rain. It has no meaning but it is inserted at the subject position to fulfill the EPP requirements. Another example of it can be the presence of dummy subject there in;

10) There comes the president.

Here, come is an intransitive verb that takes only one argument and can assign only one theta role to the president. There doesn’t get any theta role and is present to serve the purpose of EPP.

Non-finite Clauses

A non-finite clause is an embedded or dependent clause whose verb does not show tense and the time of action is generally concluded from the context of main clause. A finite clause can stand alone as an independent clause and has verb which shows tense. Therefore a finite verb construction has an expressed or implicit subject. In English, non-finite verbs consist of infinitives, participles and gerunds. A non-finite verb does not form the root of an independent clause and generally lacks an overt subject whose interpretation depends upon the subject of the main clause. For example;

11) Jane tried to cook rice.

Now, if we look at another sentence;

12) To love is to expect nothing.

Here, we see that infinitival clause is used both as the subject and object of the sentence.

Now let’s see how these separate linguistic theories or concepts together motivate the existence of PRO. For example;

13) Sita wanted to solve the question.

In the above sentence ‘to solve the question’ is a non-finite clause that doesn’t seem to have an overt subject. The absence of subject violates the EPP, so a subject is needed to fulfill the EPP requirements. The verb solve is transitive in nature and assigns two theta roles. Since there is only one NP i.e. the question, only one theta role can be assigned leaving the second theta role unassigned and therefore violating the theta criterion. In order to fulfill the theta criterion and EPP requirements there has to have something at the subject position of the non-finite clause. It is assumed that placing an abstract pronoun like element, PRO, at the subject position of non-finite clause fulfills both these requirements.

A tree diagram to show the syntactic structure of a PRO sentence is given below; Sitaᵢ wanted [PROᵢ to solve the question].

 

 

Properties of Big PRO

  • It is a null subject pronoun.
  • It can only occur at the subject position of non-finite clause.
  • It can never occur at the subject or object position of finite clause.
  • PRO theorem is another important property of PRO which states that PRO occurs only at the ungoverned positions. In English this position is also a case less position however, in other languages like Icelandic it is not a case less position.
  • It is both pronominal and anaphoric.
  • It is less flexible and its reference is always fixed to its controller that can either be arbitrary or obligatory present in the main clause.

Types of Big PRO

 

The reference of PRO is determined by its controller and on the basis of its reference PRO is of two types; controlled PRO and arbitrary PRO. Controlled PRO is further divided into two categories depending upon the verb namely, subject control PRO and object control PRO. Subject control is a situation where the reference of PRO is controlled by the subject of the main clause. For example;

 

14)  Sitaᵢ promised Radha [PROᵢ to dance].

 

Here PRO refers to Sita that is the subject of the main clause, hence, it the subject of the main clause that is the controller of PRO here. Now in a sentence like;

 

15)   Sita persuaded Radhaᵢ [PROᵢ to dance].

 

Here PRO refers to Radha that is the object of the main clause and not to Sita. Since, the object is the controller of PRO here, it is a case of object control. The other type of PRO is arbitrary PRO, where  the reference of PRO is of generic nature or arbitrary. Let’s see this sentence;

 

16)   PRO To abuse would be rude.

 

 Here, PRO has a generic or arbitrary reference which is similar to ‘one’ in, “for one to abuse would be rude.”

 

By now we have understood what PRO is, let’s focus on what we were discussing earlier regarding the behavioral features of PRO. Big PRO is both anaphoric and pronominal. Having a feature complex that includes being both anaphoric and pronominal means that;

  • The empty category must be bound in its governing category, just like an anaphor, and
  • It must be free in its governing category, just like a pronominal.

As a matter of fact any constituent that has a governor can never fulfill both these conditions at a time. So, a constituent which does not have a governor is required to solve this problem. GB theory’s case theory deals with formal features of NPs and case filter. Case filter does not allow any overt NP to be unmarked for case. It means that overt NPs can never occur without a governor since case is assigned under government. Chomsky solved this problem by concluding that the only possible candidate to occur at the ungoverned subject position of a non-finite clause is empty category PRO. Therefore PRO is a pronominal anaphor.

Small Pro (pro)

Small pro is an empty category that occupies the subject position of a finite clause in pro-drop languages. It forms the non-overt subject of finite clauses in such languages. It behave like zero or null anaphora. Therefore, it is non anaphoric but pronominal in nature. The presence of referential properties at the empty subject position is a marker of null anaphora. So, it cannot be a dummy subject. It always occurs at governed positions. Verb of a finite clause assigns external theta role to pro. It must be present at the D-structure because theta roles are assigned at the D-structure.

 

Whether a language can drop a pronoun at the subject position of a finite clause or not is guarded by pro-drop parameter. The languages which allow dropping of Pronoun at the subject position of finite clauses are called pro-drop languages. The presence of pro at the subject position of finite clause has often been linked with the richness of inflectional system of a particular language. It is said that the languages with highly rich inflectional system are often pro-drop languages that allow the insertion of non-overt empty category pro at that position. Chinese, Korean, Spanish are some of the pro-drop languages. English is not a pro-drop language. It does not have rich inflectional system. Languages that are not pro-drop allow the omission of overt subject pronoun but don’t allow the insertion of non- overt NP at the subject position of finite clauses. In English, pronouns are often dropped at the subject position of imperative sentences (e.g., go there). However, in informal speech, pronouns can sometimes be dropped at the subject position of certain other types of sentences, for example;

 

1) (Have you) ever thought of laughing and crying together?

2) (Do you) want to play?

NP-Trace

In linguistics, traces are result of movement. The concept of trace was first proposed by Wasow in 1972 and was further utilized and extended by Chomsky in GB theory. When some element in a syntactic structure moves from one syntactic position to another, it leaves behind an invisible mark at that syntactic position in that structure. That element is known as trace. So, it is a result of move-α. NP-trace is a result of A-movement i.e., movement of a determiner phrase (DP) from its underlying position to an argument position. When the DP moves to another argument position it leaves behind NP-trace. DP movement is essential for checking the case features. Therefore NP-trace occurs only at the position of spec of VP and comp of intransitive verbs, where case features cannot be checked. Passive verbs and raising verbs like seem, want etc. often result into DP-movement. They fail to assign structural case to the complement NP and also lack an external argument.

Burzio made this generalization that if a verb lacks an external theta role it fails to assign accusative case and if it fails to assign accusative case then it also fails to theta mark an external argument. For example, look at the D-structure of a this sentence;

19) Ram seems to be happy.

[ ] seems Ram to be happy,

The surface form of this sentence will be,

Ramᵢ seems [ tᵢ ] to be happy.

So, we see how subject of the infinitive embedded clause moves out its position to become the subject of the main clause leaving behind an NP-trace at its original position. NP-trace behaves like an overt anaphor and is therefore, anaphoric and not pronominal in nature.

WH-trace

WH-trace is an empty category that occurs as a result of WH-movement. In English, questions can start with Wh-words like what, who/whom, where, why, when, which and how. Wh-trace occurs when a wh-word, which is a maximal projection moves from its underlying position to the spec of CP. Spec of CP is an A’ or non-argument position. Wh-movement occurs in order to check the presence of wh-feature in C. for example, the syntactic structure of a wh-sentence can be explained by a tree diagram.

20) What will he eat?

In the above tree diagram, we see that the wh-word that originated at the NP complement position moves to the specifier position of CP, leaving behind a wh-trace. Another movement apparent here is a head movement that is a result of subject- auxiliary inversion. Last but not the least is the Empty Category Principle that deals with the last two movement generated empty categories. The following section discusses it in detail;

Empty Category Principle

 

 

The Empty Category Principle was given by Chomsky in his GB framework. It allows traces to become visible at the surface structure of a sentence as empty positions, Traces are either governed by a lexical category or are co-indexed with a maximal projection that governs it. It states that;

  •  Certain empty categories, especially traces must be properly governed.

In order to understand ECP, it is important to understand the concept of proper government. Theta government and antecedent government plays an important role in proper government. ECP results into deletion of intermediate traces as proper government is possible in case of intermediate traces. Proper government can be theorized as follows;

  • A properly governs B iff A theta governs B or A antecedent governs B. where,
  • A theta governs B iff A governs B and A theta marks B.
  • An antecedent governs B iff A governs B and A and B are co-indexed.

One of the important points to remember about Empty Category Principle is that it only covers and is generally applicable to two empty categories, namely NP-trace and Wh-trace. The reason behind it is the fact that these two empty categories are movement generated while the other two namely, Big PRO and small pro are not result of movement operations but are base generated. The main function of ECP is to put constraints on movements of different categories by the movement rule, move-α. For example, in a sentence like;

21) Where do you think (that) the thieves will go?

 

Here, the presence of an overt complementizer that forms the closest possible governor. This overt complementizer is not co-indexed with the trace, so, antecedent government is not possible here. Now, since the trace is in spec of IP it cannot be theta marked too, therefore, theta government is also not possible. ECP is violated in this sentence if the trace is in spec of IP and the complementizer that is overtly present.

Summary

 

NPs can be overtly and non-overtly present in a sentence. Overt NPs are physically present and phonetically pronounced while non-overt NPs are not physically present and pronounced at the surface structure. Anaphor, pronominal and referential expressions are three types of overt NPs and their behavioral features in a sentence is regulated by binding mechanisms. Empty category is a cover term for PRO, pro, NP-trace and Wh-trace. All these are non-overt NPs and except PRO rest of the three empty categories share behavioral features with their overt counterparts. Pro behaves like pronominal, NP-trace has the same behavioral features as that of an anaphor and wh-trace behaves like referential expressions. Out of these four empty categories, PRO and pro are base generated and the other two are movement generated. PRO is the non-overt subject occurring at the subject position of non-finite clauses that is an ungoverned position. In English, it is also a case less position. PRO can have either controlled or arbitrary reference. A control PRO can either have a reference controlled by the subject of the matrix clause, known as subject control or it can be controlled by the object of the main clause, therefore the term, object control. Arbitrary PRO has a generic reference. Small pro is the non-overt subject pronoun occurring at the subject position of finite clauses in Pro-drop languages. The presence and absence of pro at the subject position of finite clause in a language is determined by the pro-drop parameter. English is not a pro-drop language. Traces are results of movement rule move-α. When an element in syntactic structure moves from one syntactic position to the other through move-α, it leaves behind traces. Traces can be of two types namely, NP-trace and Wh-trace. NP-trace is a result of DP-movement from one argument position to another. The trace that is left  after that movement is called NP-trace. Wh-traces are results of wh-movement i.e. movement of wh- words to the spec of CP, that is movement of a maximal projection to a non-argument position. Wh- movements leave behind Wh-trace. Empty Category Principle governs two of the empty categories namely, NP-trace and Wh-trace. According to ECP, empty categories especially traces must be properly governed. This sums up empty categories.

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Reference

  • Chomsky, N. 1965. Aspects of the Theory of Syntax. MIT: MIT Press
  • Chomsky, N. 1970. “Remarks on nominalisation”. In R. Jacobs and P. Rosenbaum eds.,Readings in transformational grammar. Waltham, Mass.: Ginn and Co.
  • Chomsky, N. 1977. “On wh-movement”. In P. Culicover, T. Wasow, and A. Akmajian, eds., Formal Syntax. New York: Academic Press
  • Chomsky, N. 1981. Lectures on Government and Binding. Dordrecht: Foris
  • Duranti, A. 2001. Linguistic Anthropology: A Reader. Malden, Mass.: Blackwell
  • Wasow, T. 1972. Anaphoric Relations in English. Ph.D. dissertation, MIT.
  • Whorf, B. 1856. Language, Thought, and Reality: Selected Writings of Benjamin Lee
  • Whorf. In Carroll, John B., eds. MIT: MIT Press