An existential clause is a clause that refers to the existence or presence of something. Examples in English include the sentences "There is a God" and "There are boys in the yard". The use of such clauses can be considered analogous to existential quantification in predicate logic (often expressed with the phrase "There exist(s)...").
Different languages have different ways of forming and using existential clauses. For details about English, see English grammar: There as pronoun.
Many languages form existential clauses without any particular marker, simply using forms of the normal copula verb (the equivalent of English be), the subject being the noun (phrase) referring to the thing whose existence is asserted. For example, in Finnish, the sentence Pihalla on poikia, meaning "There are boys in the yard", is literally "On the yard is boys". Some languages have a different verb for this purpose, e.g. Swedish finnas, as in Det finns pojkar på gården, which is literally "It is found boys on the yard". On the other hand, some languages do not require a copula at all, and sentences analogous to "In the yard boys" are used. Some languages use the verb have, e.g. Serbo-Croatian, as in U dvori?tu ima dje?aka, which is literally "In the yard has boys".
Some languages form the negative of existential clauses in an irregular way; for example, in Russian, ? yest ("there is/are") is used in affirmative existential clauses (in the present tense), whereas the negative equivalent is nyet ("there is/are not"), used with the logical subject in the genitive case.
In English, existential clauses usually use the dummy subject construction (also known as expletive) with there, as in "There are boys in the yard", although there is sometimes omitted when the sentence begins with another adverbial (usually designating a place), as in "In my room (there) is a large box." Other languages with constructions similar to the English dummy subject include French (see il y a) and German (which uses es ist, es sind or es gibt, literally "it is", "it are", "it gives").
The principal meaning of existential clauses is to refer to the existence of something, or the presence of something in a particular place or time. For example, "There is a God" asserts the existence of a God, while "There is a pen on the desk" asserts the presence or existence of a pen in a particular place.
Existential clauses can be modified like other clauses in terms of tense, negation, question formation, modality (grammar), finiteness, etc. For example, one can say "There was a God", "There is not a God" ("There is no God"), "Is there a God?", "There might be a God", "He was anxious for there to be a God", etc.
Existential sentence structure is one of four structures associated within the Pingelapese language of Micronesia. This form heavily uses a post-verbal subject order. These sentences explain that something either does or does not exist. Only a few verbs are attached to existential sentence structure in Pingelapese. These verbs are minae- to exist, soh- to not exist, dir- to exist in large numbers, and daeri- to be finished. These four verbs all have a post verbal subject in common. Most of the time these verbs are used when introducing new characters to a story. If a character is already known the verb would be used in the preverbal position.
In some languages, linguistic possession (in a broad sense) is indicated by existential clauses, rather than by a verb such as have. For example, in Russian, "I have a friend" can be expressed by the sentence ? ? ? ? u menya yest' drug, literally "at me there is a friend". Russian has a verb imet' meaning "have", but it is less commonly used than the preceding method for expressing possession.
Other examples include Irish Tá ocras orm "There is hunger on me" (for "I have hunger", i.e. "I am hungry"), Hungarian Van egy halam "(There) is a fish-my" (for "I have a fish") and Turkish ?ki defterim var "two notebook-my (there) is" (for "I have two notebooks").
As an example, consider the following sentence in Hebrew:
According to linguist Ghil'ad Zuckermann, the Hebrew existential construction employed to mark possession was reinterpreted in "Israeli" (his term for "Modern Hebrew") to fit in with the "habere" (to have) construction, requiring the direct object, which is predominant in Yiddish and other European languages such as English (in "I have this book", "this book" is the direct object of "have"). Consider the following Israeli sentence:
Zuckermann argues that Israeli is a "habere language" (cf. Latin habere "to have", taking the direct object), in stark contrast to Hebrew. As demonstrated by the accusative marker et, the noun phrase ha-séfer ha-zè is the direct object in this sentence.
Yiddish has two options to indicate possession. The most common form is ikh hob, literally "I have", which requires a direct object (accusative). However, there is also a form which is more similar to old Hebrew: bay mir iz do, literally "By me is there", followed by the subject (nominative). According to Zuckermann, the latter form, available in the feature pool together with the erstwhile non-habere Hebrew structure yésh l-i + Subject (there is for me, followed by the nominative), did not prevail because ikh hob is more productive in Yiddish and other European habere languages that contributed to the emergence of "Israeli".
A similar process occurred in Maltese: "in the possessive construction, subject properties have been transferred diachronically from the possessed noun phrase to the possessor, while the possessor has all the subject properties except the form of the verb agreement that it triggers."