Accusative and infinitive

In grammar, accusative and infinitive is the name for a syntactic construction of Latin and Greek, also found in various forms in other languages such as English and Spanish. In this construction, the subject of a subordinate clause is put in the accusative case and the verb appears in the infinitive form. Among other uses, information may be given in this form to indicate indirect speech, also called indirect discourse.

The construction is often referred to by the Latin term Accusativus cum infinitivo, frequently abbreviated ACI.

In Latin

The accusative and infinitive is the usual grammatical construction by means of which Classical Latin expressed indirect statements, that is, statements which report what someone has said, thought, felt, etc. Whereas a direct statement would say

"I am a good student," says Julia.

the indirect statement might say

Julia says that she is a good student.

Latin tends not to use the word "that" to introduce indirect statements. Rather, an accusative subject is used with an infinitive to develop the appropriate meaning. For example, translating the aforementioned example into Latin:

Iūlia dīcit sē bonam discipulam esse.

literally: 'Julia says herself to be a good student.'

Sē here is an accusative reflexive pronoun referring back to the subject of the main verb i.e. Iūlia ; esse is the infinitive "to be."

Note that the tense of the infinitive, translated into English, is relative to the tense of the main verb. Present infinitives, also called contemporaneous infinitives, occur at the time of the main verb. Perfect infinitives (prior infinitives) occur at a time before the main verb. Future infinitives (subsequent infinitives) occur at a time after the main verb. For example, the contemporaneous infinitive in this sentence,

Dīxērunt eum iuvāre eam.

would still be translated "They said he was helping her," even though iuvāre is classified in Latin as a present active infinitive of the first conjugation.

Passive periphrastic infinitives, i.e. the gerundive + esse, indicate obligatory action in indirect statements, e.g. Gāius dīcit litterās tibi scrībendās esse, "Gaius says that the letter ought to be written by you."

In late classical and Medieval Latin, the ACI gradually gave way to a construction with quod.

Iūlia dīcit quod bona discipula est.

This was probably the more common usage in spoken Latin and is the form used consistently in Jerome's Vulgate, which reflects a colloquial style. It is also the equivalent of the Greek indirect statement introduced by ὅτι. This is the origin of the construction in the modern Romance languages such as French:

Julia dit qu'elle est une bonne élève.

In English and Spanish

In English, this construction occurs with verbs of wishing, saying and perception (e.g. I would like the President to be successful; I saw her go) as well as in causative clauses (e.g. She made me eat the vegetables; The teacher let him stand outside the classroom). In Spanish, it is used in causatives as well (Me obligó a mirarlo "He forced me to look at him") and in perception verbs (Los vi caminar por aquí "I saw them walk around here"), but it is not permitted in other cases. For example, in English one may say I told him to do it, but in Spanish one must say Le dije que lo hiciera "I said to him that he do it" (using the subjunctive mood), not *Le dije hacerlo; however, a colloquial usage with the preposition "de" is acceptable, which renders Le dije de hacerlo.

In the framework of transformational grammar, this construction is known as exceptional case-marking.