PRO (linguistics)
Encyclopedia
PRO is an empty category
whose existence is postulated in classical Government and Binding Theory
. There are two independent pieces of evidence for its existence: the Extended Projection Principle
(which states that all clauses must have a subject) and theta criterion
(which states that every argument a verb can assign must be realized):
In the example above, PRO serves as the subject of the non-finite clause
[to read Al Gore's latest book], thereby satisfying the EPP-feature of T (occupied by the infinitival 'to'). Since it is an object control sentence, 'John' is the antecedent of PRO, they are co-indexed.
The interpretation of PRO may be either dependent on another noun phrase
(like anaphors) or arbitrary (like pronominal
s). That is why in terms of features PRO may be described as [+anaphor, +pronominal]. However, this set of features would pose a problem for Binding
Theory: an anaphor must be bound in its governing category, whereas a pronominal must be free (in its governing category). The solution that Chomsky proposed was the so called PRO Theorem: PRO must be ungoverned. In other words, PRO cannot be governed and that is why it cannot have a governing category.
In recent literature (Chomsky 1999, Radford 2004) the existence of PRO has been argued for without the help of the PRO Theorem and government theory. It is posited that PRO is in complementary distribution
with overt subjects because it is the only item that is able to check "null case" from a nonfinite T, namely the 'to' in control infinitives. By positing this, the problems arising from the PRO Theorem are avoided. The problem was that PRO serves as the subject of the control clause and must, as such, be case-marked. However, following the traditional G&B-framework, case-marking only applies under government. Thus, PRO could not be case-marked since it must be ungoverned. If PRO receives null-case, it is licensed to appear in subject position.
On the other hand, Norbert Hornstein
(1999) has proposed that control verbs can be explained without resort to PRO, and that PRO can be done away with entirely.
Empty category
In linguistics, in the study of syntax, an empty category is a nominal element which does not have any phonological content and is therefore unpronounced; they may also be referred to as covert nouns, in contrast to overt nouns which are pronounced. There are four types of empty category:...
whose existence is postulated in classical Government and Binding Theory
Government and binding theory
Government and binding is a theory of syntax and a phrase structure grammar in the tradition of transformational grammar developed principally by Noam Chomsky in the 1980s...
. There are two independent pieces of evidence for its existence: the Extended Projection Principle
Extended projection principle
The Extended Projection Principle is a linguistic hypothesis about the obligatoriness of subjects. It was proposed by Noam Chomsky as an addendum to the Projection principle . The basic idea of the EPP is that clauses must contain an NP in the subject position The Extended Projection Principle...
(which states that all clauses must have a subject) and theta criterion
Theta Criterion
In syntax, the theta criterion states that in a grammatical sentence, every theta role that a verb can assign must be realized by some argument, and each argument may bear only a single theta role...
(which states that every argument a verb can assign must be realized):
- I persuaded John [PRO to read Al Gore's latest book]
In the example above, PRO serves as the subject of the non-finite clause
Non-finite clause
In linguistics, a non-finite clause is a dependent clause whose verb is non-finite; for example, many languages can form non-finite clauses from infinitives...
[to read Al Gore's latest book], thereby satisfying the EPP-feature of T (occupied by the infinitival 'to'). Since it is an object control sentence, 'John' is the antecedent of PRO, they are co-indexed.
The interpretation of PRO may be either dependent on another noun phrase
Noun phrase
In grammar, a noun phrase, nominal phrase, or nominal group is a phrase based on a noun, pronoun, or other noun-like word optionally accompanied by modifiers such as adjectives....
(like anaphors) or arbitrary (like pronominal
Pronominal
Pronominal can be used either to describe something related to a pronoun or to mean a phrase that acts as a pronoun in the context of nominal. An example of the second case is, "I want that kind". The phrase "that kind" stands in for a noun phrase, or nominal, that can be deduced from context, and...
s). That is why in terms of features PRO may be described as [+anaphor, +pronominal]. However, this set of features would pose a problem for Binding
Binding (linguistics)
In linguistics, binding theory is any of a broad class of theories dealing with the distribution of pronominal and anaphoric elements. The idea that there should be a specialised, coherent theory dealing with this particular set of phenomena originated in work in transformational grammar in the 1970s...
Theory: an anaphor must be bound in its governing category, whereas a pronominal must be free (in its governing category). The solution that Chomsky proposed was the so called PRO Theorem: PRO must be ungoverned. In other words, PRO cannot be governed and that is why it cannot have a governing category.
In recent literature (Chomsky 1999, Radford 2004) the existence of PRO has been argued for without the help of the PRO Theorem and government theory. It is posited that PRO is in complementary distribution
Complementary distribution
Complementary distribution in linguistics is the relationship between two different elements, where one element is found in a particular environment and the other element is found in the opposite environment...
with overt subjects because it is the only item that is able to check "null case" from a nonfinite T, namely the 'to' in control infinitives. By positing this, the problems arising from the PRO Theorem are avoided. The problem was that PRO serves as the subject of the control clause and must, as such, be case-marked. However, following the traditional G&B-framework, case-marking only applies under government. Thus, PRO could not be case-marked since it must be ungoverned. If PRO receives null-case, it is licensed to appear in subject position.
On the other hand, Norbert Hornstein
Norbert Hornstein
Norbert Hornstein is Professor of Linguistics at the University of Maryland. Working within a generative framework, he has worked on the nature of logical form, and has recently proposed that control should, like raising, be analyzed in terms of movement....
(1999) has proposed that control verbs can be explained without resort to PRO, and that PRO can be done away with entirely.