Article — Prümmer, Manuale Theologiae Moralis
Article III. On the Effect or Obligation of Contracts
260. The obligation of a contract is the bond by which someone, by force of a contract, is bound to give, do, or omit something. A threefold obligation is distinguished: natural, which binds from the very nature of the contract, but only in conscience; civil, which arises from civil law and gives rise to an action in a civil court, but does not oblige in conscience; mixed, which has force both in the forum of conscience and in the civil forum.
Every valid contract gives rise to a true obligation in the forum of conscience. The reason is that the intention of truly obliging oneself is of the essence of a contract, which on this account is held as a private law with respect to the contracting parties. The gravity of this obligation is of itself to be measured from the gravity of the matter; therefore the obligation is grave in grave matter, light in light matter.
In a qualified contract, the obligation is to be determined from the nature of the clause added. The principal clauses which are wont to be added are the following: under a condition, under a mode, under a day, under a demonstration. - A few things are to be said concerning each.
261. A contract under a condition. A condition added to a contract can be either of the present, or of the past, or of the future. If it is of the past or of the present, then, when the condition is verified, the obligation of the contract begins at once; otherwise, it does not. But a condition of the future is twofold: the one suspensive, when the obligation is suspended until the condition is fulfilled; e.g., I shall give you ten francs if you procure that book for me; the other resolutory, when the obligation of the contract already existing is afterwards revoked upon the fulfillment or non-fulfillment of the condition; e.g., I sell you this book unless it displeases you within a week, or in other words: within a week you can dissolve this contract entered.53
The effects of a suspensive condition are the following: before the event, the obligation of the contract is suspended, but it obliges one to await the event and not impede it; after the event of the condition, the obligation of the contract arises at once without new consent, and the obligation is then ordinarily considered to have existed from the day the contract was entered; but if the condition fails, no obligation arises, nor is it ever considered to have been present.54
The effects of a resolutory condition are the following: before the event and if the condition fails, the contract is valid; but when the condition is fulfilled, the contract is immediately dissolved without any sentence of a judge.
If a condition concerning a base thing is added to a contract, i.e., concerning doing something evil or omitting something good, then such a contract, as concerning a morally impossible thing, is null by natural law; nevertheless, in the external forum these conditions are sometimes held as not added, or rather are presumed as modes and not as true conditions. Ecclesiastical law establishes this for the matrimonial contract and for espousals,55 and Roman law establishes the same for testaments.56 Hence, e.g., when an uncle in a testament bequeaths 1,000 francs to his nephew under the condition that he become a Calvinist, or that he not become a religious notwithstanding a divine vocation, this condition, as being base, is held as not added, and consequently the nephew can retain the 1,000 francs although he does not fulfill the condition. But several modern civil laws do not recognize this statute of Roman law. In practice it is necessary first of all to investigate the true intention of the contracting party or testator. If it is not altogether certain that he primarily intended the base condition, the contract or testament can be ratified even if the base condition will not be verified. For then it is not a contract under a condition, but under a mode, concerning which something will be said immediately.
53 Cf. Noldin, De praeceptis n. 541.
54 Cf. Billuart, De contract. diss. 1, a. 7, § 1; German Civil Code § 158ff.; Swiss Code of Obligations, art. 151ff.
55 Cf. below, III, n. 664.
262. A contract under a mode,57 or a modal contract, is that in which the end or use of the matter concerning which the contract is made is stipulated, or in which a special burden is imposed upon one contracting party. This mode is wont to be expressed by the particles: that, for, under this law, for the purpose of, etc. E.g., I give you 100 francs that you may enter a monastery; I give you 100 francs for buying books; I lend you this garment under this law, that you may use it on such a day, etc. - A contract under a condition differs from a contract under a mode in this, that the condition suspends the obligation of the contract until the condition is fulfilled, but the mode does not suspend the effect of the contract and imposes only the obligation of observing the mode. For a mode is nothing other than a burden added to an absolute and substantially complete contract, to which it stands as the accessory to the principal.58 Therefore, a mode is never the primary motive of the contracting party. Consequently, a properly modal contract is not revoked if the mode is not observed. In practice, however, a modal contract is often distinguished from a conditional contract only with difficulty. If the mode imposed was held by either contracting party as the principal motive or at least as a condition without which not, the contract is to be considered conditional and not modal; but if the mode imposed was a secondary motive, the contract is held as modal.
57 In German: contracts with an imposed charge (Verträge mit Auflage).
58 Billuart, l.c., § 2.
263. A contract under a day or to a day59 is that whose execution is delayed to a determinate day; e.g., I give 100 francs to a monastery when my father dies. A contract under a day immediately gives rise to an obligation, but not for immediate execution. Therefore, if the one promising dies before the day for executing the contract, the heirs must execute the promise made. But if the promise was made for an uncertain day, i.e., one not certainly future - e.g., I shall give you 100 francs on the day on which my daughter enters a monastery - such a contract is not under a day but under a condition, and consequently does not oblige immediately. Hence if I die before my daughter's entrance into a monastery, my heirs are not bound to pay the 100 francs promised. For the rest, in practice the intention of the one promising must first of all be attended to.
59 In German: with a determination of time or a time limit (mit Zeitbestimmung oder Befristung).
264. A contract under a demonstration is called that in which the matter of the contract is designated not accurately but rather in a broad manner. For the quantity of the thing can be designated either demonstratively, if the thing itself is first expressed and then the quantity of the thing only secondarily; or taxatively, if first the quantity and then the thing is expressed. E.g.: I give you such a chest, which contains 100 francs. This is a demonstrative designation. I give you 100 francs, which are contained in that chest. This is a taxative designation. Now if an error occurs in designating the quantity, a contract entered under a demonstration is valid, but not one effected under a taxation. Thus the common opinion. E.g., if an uncle says to his niece: I give you this chest, which contains 100 francs, the niece can retain the chest with the money even if perhaps 200 francs are enclosed. On the contrary, if the uncle had said: I give you 100 francs, which are enclosed in this chest, the niece could not retain the 200 francs which were in fact found in the chest. For the rest, in practice all things depend upon the intention of the contracting party, and the principles set forth above concerning error occurring in a contract are to be applied.
265. On an oath which is joined to a contract.
Sometimes a promissory oath is added to a contract, by which the contracting party, under invocation of the divine name, obliges himself to fulfill the contract; e.g., a young man promises marriage to a girl and swears that he will keep the promise made. Very rarely is an assertory oath added to a contract.60 Concerning the efficacy of this promissory oath added to a contract, the following holds:
Principle: All contracts are not changed in their character as contracts by an added oath.
I say, however: in their character as contracts, for in a valid sworn contract there is a twofold obligation: the one of justice by force of the contract, the violation of which induces an obligation of repairing the damage inflicted; the other of religion by force of the oath, the violation of which is indeed a grave sin but by no means of itself imposes restitution. The reason for the stated principle is that a promissory oath is added to a contract as an accident. But the common adage says: "The accessory follows the principal." Hence the Code of Canon Law, c. 1318, § 1, also establishes generally: "A promissory oath follows the nature and conditions of the act to which it is added."
60 Cf. Billuart, De contract. diss. 1, a. 6.
266. Corollaries. 1. Neither the contract nor the oath is valid if there is question of a thing or action which cannot be furnished without sin. The reason is that no one can oblige himself to a sinful act. Hence all base sworn contracts are invalid, so that they ought not to be executed.
An oath appended to a contract which is invalidated and prohibited: a) by natural law; or b) by positive law on account of the common good, is null. - Hence an oath of a cleric by which he renounces the privilege of canon is null, because such a privilege was given for the common good rather than private good; likewise, an oath by which someone under grave fear obliges himself to enter marriage is null, because the Church placed the impediment of fear in matrimony on account of the common good, namely, for avoiding hatreds, scandals, etc.
An oath appended to a contract which indeed induces a natural obligation, but is rescinded by positive law principally in favor of the contracting party, is valid. The reason is that the obligation of an oath is to be sustained as long as it is licitly observed. But in this case the oath can licitly be observed. Therefore Alexander III already said: "It is not safe for anyone to act against his oath unless it is of such a kind that, if observed, it would tend toward the destruction of eternal salvation."61 Hence a minor who promised by oath that he would not rescind the contract must observe it unless a legitimate dispensation has been obtained. When and how dispensation can be obtained in a promissory oath will be said below, n. 454, in the tract on religion.62
An oath and a contract extorted by fear are valid (unless declared invalid by positive law), but they can be rescinded by legitimate authority. It has already been said above, n. 258, that a contract entered through fear is commonly valid, because fear does not remove freedom. Likewise, an oath extorted by fear is valid, and therefore the Code of Canon Law, c. 1317, § 2, establishes: "An oath extorted by force or grave fear is valid, but it can be relaxed by an ecclesiastical superior." Hence, if someone from fear of death swears that he will give a sum of money to a robber, he is bound to give it both by force of the promise and by force of the oath; nevertheless, he can petition legitimate authority either for rescission of the contract and dispensation from the oath, or for punishment of the robber. Thus St. Thomas,63 and St. Alphonsus64 calls this opinion far more probable. For the general rule is that every oath which can be fulfilled without sin is to be observed in the forum of conscience. - Cf. Billuart,65 who rightly insists greatly upon the difference between the obligation arising from a contract and that arising from an oath. The first obligation is real and passes to the heirs. Its violation induces a debt of restitution. The second obligation is personal and does not pass to the heirs, nor does its violation bring with it a debt of restitution. Hence, e.g., if someone swore that he would never revoke a testament and nevertheless afterwards revoked it, he is indeed perjured, but the revocation of the testament is valid, and neither the perjurer nor his heirs are bound to restitution.
61 c. 8, X 2, 24.
62 Cf. Göpfert, Der Eid, n. 276ff.
63 S. theol. 2, 2, q. 89, a. 7 ad 3.
64 Theol. mor. l. 3, n. 174.
65 L.c.