Dummy subject

A dummy pronoun, also called an expletive pronoun or pleonastic pronoun, is a pronoun used for syntax without explicit meaning.

Dummy pronouns are used in many Germanic languages such as English. Pronoun-dropping languages such as Spanish, Portuguese, Chinese, and Turkish do not require dummy pronouns.

A dummy pronoun is used when a particular verb argument (or preposition) is nonexistent (it could also be unknown, irrelevant, already understood, or otherwise "not to be spoken of directly"), but when a reference to the argument (a pronoun) is nevertheless syntactically required. For instance, in the phrase, It is obvious that the violence will continue, it is a dummy pronoun, not referring to any agent. Unlike a regular pronoun of English, it cannot be replaced by any noun phrase (except for, rhetorically permitting, something like 'the state of affairs' or 'the fact of the matter'.)

The term dummy pronoun refers to the function of a word in a particular sentence, not a property of individual words. For example, it in the example from the previous paragraph is a dummy pronoun, but it in the sentence I bought a sandwich and ate it is a referential pronoun (referring to the sandwich).

In the phrase It is raining, the verb to rain is usually considered semantically impersonal, even though it appears as syntactically intransitive; in this view, the required it is to be considered a dummy word.

However, there have been a few objections to this interpretation. Noam Chomsky has argued that the it employed as the subject of English weather verbs ("weather it", so called because of its predominant use in reference to weather) can control an adjunct clause, just like a "normal" subject. For example, compare:

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