(d) it must be free, that is, it must have the advertence and voluntariness necessary for a human act. If the contract is of grave import, there should be the same kind of deliberation as is necessary for commission of a mortal sin (see 173 sqq.); if it is of lesser import, the deliberation should correspond with the seriousness of the case. But some authors think there should be perfect deliberation in every contract, since the contractants are assuming obligations of justice.
1884. Defects that Invalidate Consent.—The defects that vitiate consent by taking away knowledge or choice render contracts either void or voidable (see 40-55). These impediments are the following:
(a) error, which is a judgment of fact or of law in reference to the contract, not in harmony with the truth, but not maliciously caused by other persons. If error is substantial (that is, about the nature of the contract or the nature of the subject-matter of the contract), the agreement is naturally void; if error is only accidental (that is, about features of the contract, subject-matter or co-contractant, that are only incidentally intended), an onerous agreement is naturally valid, but positive law in the interest of freedom will often grant the privilege of rescindment (see Canon 1684, n. 2). But if error cannot be proved, courts will stand for the validity of a contract;
(b) fraud, which is error or mistake about a contract caused in one of the parties by the dishonest representations of the other party or of a third person (e.g., when an insurance agent deceives about the benefits, or a policy-taker deceives about his age or health). Fraud exists, then, when there is intention, at least indirect, to mislead, and statements, acts or omissions calculated to mislead; but the usual boasts of vendors and advertisers about the wonderful excellence of their wares are not fraudulent, since the public understands that such talk must be taken _cum grano salis_. The effects of fraud on the value of contracts are the same as those produced by error; but it should be noted that the person guilty of the fraud is bound to make good the losses of the injured party, even though the contract be valid and not rescindable, or though the guilty person be not a party to the contract;
(c) fear, which is a disturbance of mind caused by the belief that some danger is impending on oneself or others (see 41 sqq.). It makes a contract invalid in natural law, when it takes away all consent (e.g., when it overpowers the reason, or makes one dissent internally from what is agreed to externally), and probably also when it takes away perfect freedom in a gratuitous contract, or makes one enter into a contract for immunity from an unjust vexation; it renders an act or engagement invalid according to positive law in many special cases (e.g., the Canons declare null elections, resignations, marriages, vows, etc., which are made under the influence of fear). Contracts are considered naturally voidable if one of the parties unjustly extorts the consent of the other by grave fear, or if a third party intimidates a person into bestowing something through gratuitous contract; and the positive law generally treats agreements entered into under grave fear as rescindible (see Canon 103, n. 2). Fear unjustly caused, even though it does not make a contract void or voidable, is at times a reason for the duty of restitution, as when a third party by his unjust threats forces an innocent person to make expensive contracts as a measure of protection, and probably also when a third party directly constrains one to make an onerous contract with a person who knows nothing about the coercion. Fear, no matter how great, does not in any way weaken a contract, if there is consent and the fear is induced by a natural cause (e.g., a storm), or by a human cause acting justly (e.g., an injured man threatening a lawsuit);
(d) violence or coercion, which is like to fear, the latter being moral force and the former physical force (see 52). According to natural law, violence invalidates a contract, unless we suppose that it is only concomitant, as when Sempronius uses coercion to make Balbus sign a contract which Balbus is really willing to sign. Positive law does not recognize, or will set aside, agreements made under overpowering constraint (see Canon 103, n. 1).
1885. Form of Contract.—The form of a contract is the external manner in which, according to the positive law, the internal consent of the parties must be expressed and manifested.
(a) Thus, Canon Law in certain contracts (e.g., engagement of marriage, marriage, alienation of church property) requires specified solemnities under pain of nullity of act.
(b) Civil law in the United States designates various formalities to be used in transfers of property (e.g., that a deed for real estate be written, signed, sealed and attested; that a gift be made by delivery or equivalent act; that certain contracts be in writing; that no contract be of worth unless it be for a consideration, or else be on paper with seal attached). The law has the right to annul informal contracts _ipso facto_, but whether this is the intention in modern codes is a matter of dispute. The practical rule to be followed, then, is that the possessor is to be favored, unless there has been a court decision against his claim. It should be noted, too, that some legal conditions, such as valuable consideration in simple contracts, are required for enforceability, not for validity, and hence a good contract wanting some such condition, though indefensible before the courts, is obligatory in conscience.
1886. The Accidentals of a Contract.—(a) Bond is the agreement by the obligor of a contract to pay a certain forfeit to the obligee, if the former does not perform his contract or does not perform it before a certain date. This agreement obliges in conscience, if the promise was seriously made, if the penalty is not excessive, and if the breach of agreement is culpable.