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. 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 they 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 the revocation of it which might prevent acceptance: and this effect results, not from NATURAL but from purely LEGAL rules.