CONSENT. — In its broadest meaning, it is the adherence of the will to the idea presented by the intellect: it is a necessary element for a human act to be called free and voluntary and thus to enter the ethical order (v. ATTO UMANO). Human action is voluntary insofar as it proceeds from the deliberating will, that is, illuminated by the intellect, which perceives the relation of the act to its end: all actions performed without the deliberation and c. of the will (in madness, in grave fear that disturbs reason, in violence that constrains a reluctant will, in first-first movements, in sleep, etc.) are neither voluntary nor free and are therefore not susceptible to moral evaluation. Likewise, actions in which deliberation and c. are not full and perfect are not perfectly free and voluntary and are less culpable (v. PECCATO, mortale e veniale).
In law, c. is spoken of in two different senses: as the meeting of two wills that agree in regulating one or more juridical relationships, and as the approval, by a person possessing authority (public or private), of another person’s decision and act.
In the first sense, the notion of c. is relevant to the matter of contracts (v. CONTRATTO). Indeed, in contrast with the Roman principle according to which the principal mode of transferring ownership was the traditio rei, the delivery of the thing, the radical and important innovation of the modern codes, which derive from the Napoleonic Code (Albertine, Italian), consists in having established the moment and effect of the transfer of ownership or of a right in the legitimate manifestation of c. This innovation is an achievement both logically and juridically: the contract is essentially and juridically bilateral in nature and already exists in the meeting of two wills which, being internal spiritual faculties, cannot be seen, assessed, or have social effects except insofar as they are manifested: in manifested c. The classical Roman definition of contract is now clear: Duorum vel plurium in idem placitum consensu.
The external manifestation of the will, or internal c., may take place in different ways and by different means: expressly or tacitly (silence too may manifest a will, when circumstances are such that remaining silent is equivalent to an explicit response; this equivalence exists, however, only when the person who remains silent would in any event have had to give express consent or dissent).
It may happen that a will different from that actually existing in the subject’s consciousness is manifested: mental reservation (v.) error (v.), simulation (v.).
It has been said that in modern law c. by itself transfers rights; but if the contract is made between absent parties, when is c. deemed perfected? The principles of the Italian Civil Code may be summarized as follows: agreement is considered to have been reached, and therefore the contract concluded, at the moment when the person who made the offer becomes aware of the other party’s acceptance (art. 1326). Such knowledge is presumed at the moment when the acceptance reaches the offeror’s address, unless the latter proves that, through no fault of his own, he was unable to learn of what had reached him (art. 1335). Until the contract is concluded, the offer and acceptance may as a rule be revoked, subject to compensation for anyone who in good faith has begun performance (art. 1328); when, however, contracts involve unilateral obligations of the offeror (suretyship, offer by the surety), the offer is irrevocable once it comes to the addressee’s knowledge (art. 1333).
The defects of c., as listed by jurisprudence, are causes that affect the formation of the act of will, so that without them c. would not have existed or would have been different. In this case, therefore, there is one will that has actually been formed and manifested, and another that has neither been formed nor manifested, but that would have been formed and manifested if the cause had not exerted its influence. Such causes are: error, fraud (v.), violence (v.).
With particular regard to c. in custom and in marriage, V. the respective entries.