Null subject language
In linguistic typology, a null subject language is a language whose grammar permits an independent clause to lack an explicit subject. Such a clause is then said to have a null subject. Typically, null subject languages express person, number, and/or gender agreement with the referent on the verb, rendering a subject noun phrase redundant.
For example, in Italian:
The subject "she" of the second sentence is only implied in Italian. English, on the other hand, requires an explicit subject in this sentence.
Of the thousands of languages in the world, a considerable part are null subject languages, from a wide diversity of unrelated language families. They include Spanish, Portuguese, Slovak, Tamil, Finnish, Persian, Hindi, Arabic, Chinese, and Japanese, as well as most languages related to these, and many others still.
In the framework of government and binding theory of syntax, the term null subject refers to an empty category. The empty category in question is thought to behave like an ordinary pronoun with respect to anaphoric reference and other grammatical behavior. Hence it is most commonly referred to as "pro".
This phenomenon is similar, but not identical, to that of pro-drop languages, which may omit pronouns, including subject pronouns, but also object pronouns. While pro-drop languages are null subject languages, not all null subject languages are pro-drop.
In null subject languages that have verb inflection in which the verb inflects for person, the grammatical person of the subject is reflected by the inflection of the verb, and likewise for number and gender.
The following examples come from Portuguese:
As the examples illustrate, in many null subject languages, personal pronouns exist, and they can be used for emphasis, but are dropped whenever they can be inferred from the context. Some sentences do not allow a subject in any form, while in other cases an explicit subject without particular emphasis would sound awkward or unnatural.
Japanese and several other null subject languages are topic-prominent languages; some of these languages require an expressed topic in order for sentences to make sense. In Japanese, for example, it is possible to start a sentence with a topic marked by the particle wa, and in subsequent sentences leave the topic unstated, as it is understood to remain the same, until another one is either explicitly or implicitly introduced. For example, in the second sentence below, the subject ("we") is not expressed again but left implicit:
In other cases, the topic can be changed without being explicitly stated, as in the following example, where the topic changes implicitly from "today" to "I".
In some cases (impersonal constructions), a proposition has no referent at all. Pro-drop languages deal naturally with these, whereas many non-pro-drop languages such as English and French have to fill in the syntactic gap by inserting a dummy pronoun. "*Rains" is not a correct sentence; a dummy "it" has to be added: "It rains", French "Il pleut". In most Romance languages, however, "Rains" can be a sentence: Spanish "Llueve", Italian "Piove", Catalan "Plou", Portuguese "Chove", Romanian "Plouǎ", etc.
There are some languages that are not pro-drop but do not require this syntactic gap to be filled. For example, in Esperanto, "He made the cake" would translate as Li faris la kukon (never *Faris la kukon), but It rained yesterday would be Pluvis hierau (not *Ĝi pluvis hieraŭ).
Null subjects in non-null subject languages
Other languages (sometimes called non-null subject languages) require each sentence to include a subject - this is the case for most Germanic languages, such as English and German, but also in French, a Romance language, and many others. In some cases, colloquial expressions, particularly in English, less so in German, and extremely rarely in French, allow for the omission of the subject in the same way that languages such as Spanish and Russian allow using "correct" grammar:
The imperative form
Even in such non-null subject languages as English, it is standard for clauses in the imperative mood to lack explicit subjects; for example:
An explicit declaration of the pronoun in English in the imperative mood is possible, usually for emphasis but not necessary:
French and German offer less flexibility with regards to null subjects. In French, it is neither grammatically correct nor possible to include the subject within the imperative form (the vous in the expression taisez-vous would stem from the fact that se taire, to be silent is a reflexive verb and is thus the object).
In German, the informal form du may be added to the imperative in a colloquial manner for emphasis (Mach du das, you do it). The formal imperative requires the addition of the subject Sie (as in Machen Sie das) as the formal imperative form of a verb is identical to the infinitive (which also can be used as a "neutral" imperative).
Many international auxiliary languages, while not officially pro-drop, permit pronoun omission with some regularity. In Interlingua, pronoun omission is most common with the pronoun il, which means "it" when referring to part of a sentence or to nothing in particular. Examples of this word include
Il tends to be omitted whenever the contraction "it's" can be used in English. Thus, il may be omitted from the second sentence above: "Es ver que ille arriva deman". In addition, subject pronouns are sometimes omitted when they can be inferred from a previous sentence:
Similarly, Esperanto sometimes exhibits pronoun deletion in casual use. This deletion is normally limited to subject pronouns, especially where the pronoun has been used just previously:
Published - November 2008
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