Chapter 11b

Promises in Error

July 12, 2022

Part 6:

The consideration of promises, made under an error, is a subject of some intricacy.

It makes a difference whether:

  • the promiser knew the full extent of his promise, and the value of the thing promised, or not, or
  • whether the contract, which was made, originated in fraudulent intention, or not, or whether one of the parties was privy to the fraud;
  • whether the fulfilment of it was an act of strict justice, or only of good faith. For according to the variety of these circumstances, writers pronounce some acts void and others valid, leaving the injured party a discretionary power to rescind or amend them.

Most of these distinctions originate in the ancient civil, and praetorian Roman law.

Though some of them are not strictly founded in reason and truth. But the most obvious and natural way of discovering the truth is by referring to laws, which derive their force and efficacy from the general consent of mankind; so that if a law rests upon the presumption of any fact, which in reality has no existence, such a law is not binding. For when no evidence of the fact can be produced, the entire foundation, on which that law rests must fail. But we must have recourse to the subject, to the words and circumstances of a law, to determine when it is founded on such a presumption.27

The same rule applies to the interpretation of promises. For where they are made upon the supposition of a fact, which in the end proves not to be true, they lose the force of obligations. Because the promiser made them upon certain conditions only, the fulfilment of which becomes impossible. Cicero, in his first book on the talents and character of an orator, puts the case of a father, who, under the supposition or intelligence that his son was dead, promised to devise his property to his nephew. But the supposition proving erroneous, and the intelligence false, the father was released from the obligation of the promise made to his relative. But if the promiser has neglected to examine the matter, or has been careless in expressing his meaning, he will be bound to repair the damage which another has sustained on that account. This obligation is not built on the strength of the promise, but on the injury, which it has occasioned. An erroneous promise will be binding, if the error was not the OCCASION of the promise. For here there is no want of consent in the party, who made it. But if the promise was obtained by fraud, the person so obtaining it shall indemnify the promiser for the injury sustained, if there has been any partial error in the promise, yet in other respects it shall be deemed valid.

VII. Promises extorted by fear are a subject of no less intricate decision. For here too a distinction is usually made between a well founded and a chimerical fear, between a just fear and a bare suspicion, and between the persons who occasion it, whether it be the person to whom the promise is given, or some other. A distinction is also made between acts purely gratuitous, and those in which both parties have an interest. For according to all this variety of circumstances some engagements are considered as void, others as revocable at the pleasure or discretion of the maker, and others as warranting a claim to indemnity for the inconvenience occasioned. But on each of these points there is great diversity of opinion.

There is some shew of reason in the opinion of those who, without taking into consideration the power of the civil law to annul or diminish an obligation, maintain that a person is bound to fulfil a promise which he has given under impressions of fear. For even in this case there was CONSENT, though it was extorted; neither was it conditional, as in erroneous promises, but absolute.138 It is called CONSENT. For as Aristotle has observed, those who consent to throw their goods overboard in a storm, would have saved them, had it not been for the fear of shipwreck. But they freely part with them considering all the circumstances of time and place.

VIII. To render a promise valid, it must be such as it is in the power of the promiser to perform. For which reason no promises to do illegal acts are valid; because no one either has, or ever can have a right to do them. But a promise, as was said before, derives all its force from the right of the promiser to make it, nor can it extend beyond that.

If a thing is not now in the power of the promiser, but may be so at some future time; the obligation will remain in suspense. For the promise was only made under the expectation of some future ability to fulfil it. But if a person has a controul over the condition upon which the promise is made, to realise it or not, he lies under a moral obligation to use every endeavour to fulfil it. But in obligations of this kind also, the civil law, from obvious motives of general utility, occasionally interposes its authority to make them void: obligations, which the law of nature would have confirmed.

IX. The next general inquiry, for the most part, refers to the validity of promises made upon any immoral or unlawful consideration; as if, for instance, any thing is promised to another on condition of his committing a murder. Here the very promise itself is wicked and unlawful, because it encourages the commission of a crime. But it does not follow every FOOLISH or IMPROVIDENT promise loses the force of an obligation, as in the confirmation of imprudent or prodigal grants, for no further evil can result from a confirmation of what has been already given: and the invalidity of promises would be a greater evil than any that could result from a confirmation of the most improvident. But in promises made upon IMMORAL and UNLAWFUL considerations, there is always a criminality remaining, even while they continue unfulfilled. For during the whole of that time, the expectation of fulfilment carries with it the indelible mark of encouragement to the commission of a crime.

XII.28 We are obliged to confirm the engagements made by others, acting in our name, if it is evident that they139 had special, or general instructions from us to do so. And in granting a commission with full powers to any one, it may so happen that we are bound by the conduct of that agent, even if he exceed the secret instructions which he has received. For he acts upon that ostensible authority, by which we are bound to ratify whatever he does, although we may have bound him to do nothing but according to his private instructions. This rule, we must observe, applies to the promises made by ambassadors in the name of their sovereigns, when, by virtue of their public credentials, they have exceeded their private orders.

XIII. From the preceding arguments, it is easy to understand how far owners of ships are answerable for the acts of the masters employed by them in those vessels, or merchants for the conduct of their factors. For natural equity will qualify the actions brought against them, according to the instructions and powers which they give. So that we may justly condemn the rigour of the Roman law, in making the owners of ships absolutely bound by all the acts of the masters employed. For this is neither consonant to natural equity, which holds it sufficient for each party to be answerable in proportion to his share, nor is it conducive to the public good. For men would be deterred from employing ships, if they lay under the perpetual fear of being answerable for the acts of their masters to an unlimited extent. And therefore in Holland, a country where trade has flourished with the greatest vigour, the Roman law has never been observed either now or at any former period. On the contrary, it is an established rule that no action can be maintained against the owner for any greater sum than the value of the ship and cargo.

For a promise to convey a right, acceptance is no less necessary than in a transfer of property. And in this case there is supposed to have been a precedent request, which is the same as acceptance. Nor is this contradicted by the promises which the civil law implies every one to have made to the state, WITHOUT ANY REQUEST OR FORMAL ACCEPTANCE.

XIV. A reason which has induced some to believe that the sole act of a promiser, by the law of nature, is sufficient. Our first position is not contradicted by the Roman law. For it no where says, that a promise has its full effect before acceptance, but only forbids the140 revocation of it which might prevent acceptance: and this effect results, not from NATURAL but from purely LEGAL rules.

XV. Another question is, whether the acceptance alone of a promise is sufficient, or whether it ought to be communicated to the promiser before it can be made binding.

It is certain that a promise may be made two ways, either upon condition of its being fulfilled, if accepted, or upon condition of its being ratified, if the promiser is apprised of its being accepted. And in cases of mutual obligation, it is presumed to be taken in the latter sense; but it is better to take promises that are purely gratuitous in the former sense, unless there be evidence to the contrary.

XVI. From hence it follows, that a promise may be revoked, without the imputation of injustice or levity, BEFORE ACCEPTANCE, as no right has yet been conveyed; especially if ACCEPTANCE were made the condition of its being fulfilled. It may be revoked too if the party to whom it was made, should die before acceptance. Because it is evident that the power to accept it or not, was conferred upon HIM, and not upon his HEIRS. For to give a man a right, which may POSSIBLY descend to his heirs, is one thing, and to express an intention of giving it to his heirs is another. For it makes an essential difference upon what person the favour is conferred. This is understood in the answer made by Neratius, who said, that he did not believe the prince would have granted to one who was dead, what he granted, supposing him still alive.

XVII. A promise may be revoked, by the death of the person appointed to communicate to a third the intention of the promiser. Because the obligation to the third person rested upon such communication. The case is different, where a public messenger is employed, who is not himself the obligatory instrument, but only the means through which it is conveyed. Therefore letters indicating a promise, or consent may be conveyed by any one. Yet there is a distinction to be made between a minister appointed to communicate a promise, and one appointed to make the promise in his own name.

For in the former case, a revocation will be valid, even though it has not been made known to the minister employed; but in the latter case, it will be entirely void,141 because the right of promising was committed to the minister, and fully depended upon his will; therefore the obligation of the promise was complete, as he knew of no intended revocation. So also in the former case, where a second person is commissioned to communicate the intentions of a donor to a third; even if the donor should die, the acceptance of the gift will be deemed valid, all that was requisite being performed on one part; though till that period the intention was revocable, as is evident in the case of bequests. But in the other case, where a person has received a full commission to execute a promise during the LIFE of the donor, should the donor die before the execution of it, and the person employed be apprised of his death; the commission, the promise, and the acceptance of it will then, at once, become void.

In doubtful cases, it is reasonable to suppose that it was the intention of the promiser, that the commission which he gave should be executed, unless some great change, as for instance, his own death should occur. Yet reasons in favour of a contrary opinion may easily be found and admitted, especially with respect to pious donations, which, at all events, ought to stand good. And in the same manner may be decided the long disputed question, whether an action on account of such a bequest could be brought against the heir. Upon which the author of the second book to Herennius says, that Marcus Drusus the praetor decided one way, and Sextus Julius another.


The acceptance of a promise for a third person is a matter subject to discussion, in which there is a distinction to be observed between a promise made to a person of a thing, which is to be given to another, and a promise made directly to the person himself, on whom the former is to be conferred.

If a promise is made to any one, where his own personal interest is not concerned, a consideration introduced by the Roman law, by acceptance he seems naturally to acquire a right which may be transferred to another for HIS acceptance, and this right will pass so fully, that in the mean time the promise cannot be revoked by the person who gave, though it may be released by him who received it. For that is a meaning by no means repugnant to the law of nature, and it is entirely conformable to the words of such a promise; nor can it be a matter of indifference to142 the person, through whom another is to receive a benefit.

But if a promise is made directly to one, on whom a thing is to be conferred, a distinction must be made, whether the person receiving such a promise has SPECIAL commission for acceptance, or one so GENERAL as to include acceptance, or has it not. When a commission has been previously given, no farther distinction is necessary, whether the person be free or not, a condition which the Roman laws require. But it is plain that from such an acceptance, let the condition of the person be what it will, the promise is complete: because consent may be given and signified through the medium of another. For a person is supposed to have fully intended, what he has put into the power of another to accept or refuse.

Where there is no such commission, if another, to whom the promise was not directly made, accepts it with the consent of the promiser, the promise will be so far binding, that the promiser will not be at liberty to revoke it, before the person, in whose favour it was made has ratified, and afterwards chosen to release the engagement. Yet, in the mean time, the accepter cannot release it, as having derived no peculiar right from it himself, but only been used as an instrument in promoting the kind intentions and good faith of the promiser. The promiser therefore himself, by revoking it, is not doing violence to the perfect right of another, but only acting in contradiction his own good faith.

Part 19.

A burdensome condition annexed to a promise might be annexed at any time before the promise has been completed by acceptance, or an irrevocable pledge to fulfil it has been given.

But the condition of a burden annexed to a favour intended to be conferred upon a third person, through the medium of any one, may be revoked before the person has confirmed it by his acceptance. On this point there is great difference of opinion. But upon impartial consideration the natural equity of any case may be easily seen without any great length of arguments.

Parts 20-22

What about the validity of an erroneous promise?

A promiser learns of his error but is willing to fulfill it anyway because of fear or any other such motive which are prohibited by the civil law.

To confirm such obligations, some think an internal consent of the mind alone in conjunction with some previous external act is sufficient. Others disapprove of this opinion, because they do not admit that an external act is a real sign of a subsequent intention. Therefore they require an express repetition of the promise and acceptance. Between these two opinions, the truth is most likely to be found. There may be an external act expressive of a promise, though unaccompanied with words; where one party’s accepting and retaining a gift, and the other’s relinquishing his right in it are sufficient to constitute a full consent.

To prevent civil laws from being confounded with natural justice, we must not omit noticing, in this place, that promises though founded in no EXPRESS motive, are not, any more than gifts, void by the law of nature.

Nor is a person who has engaged for another’s performing any thing, bound to pay damages and interest for neglect, provided he has done every thing that was necessary on his part towards obtaining its accomplishment. Unless the express terms of the agreement, or the nature of the business require a stricter obligation, positively declaring that, under all circumstances whatever, the thing shall be performed.