CHAPTER IX 

       On the Duties of Contracting Parties in General



1. From the absolute duties we pass to the conditional, by way of agreements 

as a transition; since all the duties not already enumerated seem to 

presuppose an express or tacit agreement. We have then to treat here of the 

nature of agreements, and what is to be observed by those who enter into 

them.



2. Now it is sufficiently clear that it was necessary for men to enter into 

agreements. For, although the duties of humanity are widely diffused 

throughout human life, it is still impossible to deduce from that one source 

all that men were entitled to receive to advantage from one another. For not 

all have such natural goodness, that they are willing, out of mere humanity, 

to do all the things by means of which they may benefit others, without an 

assured hope of receiving the like in return. Often, too, favors which can 

come to us from others, are of a sort to make us unable to demand without a 

blush that they be done for us for nothing. And frequently it is unbecoming 

to our station or person to owe such a favor to another. And in fact, as the 

other is unable to give much, so we are often unwilling to accept, unless he 

receives an equivalent from us. Finally, not uncommonly others are in the 

dark as to how they may serve our interests. Therefore, in order that the 

mutual duties of men (the fruit, that is, of sociability) may be discharged 

more frequently and according to certain rules, it was necessary for men to 

agree among themselves, as to the mutual performance of all that they could 

not certainly promise themselves from others, on the basis of the law of 

humanity alone. And indeed it was necessary to determine in advance, what 

one was bound to perform for another, and what the latter should in turn 

expect and exact as his right from the former. And this is done by promises 

and agreements.



3. In regard to these, the general duty which we owe under natural law is, 

that a man keep his plighted word, that is, fulfill his promises and 

agreements. For, but for this, we should lose the greatest part of the 

advantage which is apt to arise for the race from the interchange of 

services and property. And were there not the necessity of keeping promises, 

one could not build one's calculations firmly upon the support of others. 

And also from a breach of faith there are apt to arise entirely just causes 

for quarrels and war. For when I have performed something in accordance with 

an agreement, if the other defaults his promise, I have lost my property, or 

my services, for nothing. But if, on the other hand, I have not yet 

performed anything, it is still an annoyance to have my calculations and 

plans disturbed, since I could have made other provision for my affairs, if 

he had not presented himself. And it is a shame to be mocked because I 

believed the other a prudent and honest man.



4. We must observe also, that what we owe under the mere duty of humanity 

differs from what is owed by virtue of a compact or perfect promise 

especially in this respect, viz., that things of the former class are 

properly asked, and honorably performed; but when the other has failed of 

his own motion to perform, I can complain merely of his inhumanity, 

barbarity, or harshness; but I cannot compel him to perform, by my own force 

or that of my superior. This is my privilege, however, when he does not of 

himself perform what is due in accordance with a perfect promise or a 

compact. Hence we are said in the former case to have an imperfect right, in 

the latter, a perfect right, as also to be obligated imperfectly in the one 

case, and perfectly in the other.



5. We give our word either by a solitary, or one-sided, act, or by a 

reciprocal, or two-sided, act. For sometimes one man merely binds himself to 

some performance, sometimes two or more bind themselves mutually to some 

performance. The former act is called a gratuitous promise, the latter a 

compact.



6. Promises can be divided into the imperfect and the perfect. We have the 

former when we who promise[10] are indeed willing to be bound, in such a 

way, however, that we do not give the other the right to exact, or are 

unwilling to be compelled by force to fulfill our promise. For example, if I 

thus frame my promise: "I have determined in all seriousness to perform this 

or that for you; and I ask you to believe me." For thus I seem obligated 

rather under the law of veracity, than that of justice; and I prefer to be 

thought impelled to discharge the duty by my own constancy and solidity of 

character, rather than in view of another's right. Here belong the promises 

of men of power or influence, when in seriousness, and not in compliment 

they pledge to a man their recommendation, intercession, advancement, or 

support. They do not, however, desire by any means that these things be 

exacted of them as by some right, but wish to have them set down wholly to 

their humanity and their veracity, so that gratitude for performing their 

duty may be the greater, the further it was removed from compulsion.



7. A perfect promise, on the other hand, is when I am not only willing to be 

bound in any case, but also confer upon the other at the same time a right, 

so that he can demand of me in full, as owed to him, the thing I promised.



8. Moreover, that promises and compacts may bind us to give or do something 

not formerly required of us, or to omit what we previously had a right to 

do, our voluntary consent is most essential. For, since the fulfillment of 

any promise and agreement is associated with some burden, there is no better 

reason to prevent our justly complaining about it, than the fact that we 

voluntarily consented to what it was evidently in our own power to avoid.



9. Consent is, to be sure, regularly and usually expressed by signs, for 

example, words, letters, and nods; but it sometimes happens that without 

these signs, from the very nature of the business and other circumstances, 

consent is clearly inferred. Thus at times silence, considered together with 

certain circumstances, is effective, instead of a sign of consent. Hence 

there are also tacit agreements, namely when our consent is expressed not by 

such signs as are regularly accepted in men's intercourse; but when it is 

clearly inferred from the nature of the business and other circumstances. So 

too, a principal agreement has often attached to it a tacit agreement, which 

flows from the very nature of the business. And so also it is very common in 

compacts for certain tacit exceptions and necessary conditions to be 

understood.



10. But to be able to give clear consent, the use of reason is required to 

this extent, that one understand the business in hand, whether it is proper 

for one, and can be performed by one; and then, when this has been weighed, 

that one be able to indicate his consent by sufficient signs. Hence it 

follows that the promises and agreements of infants, as also of idiots and 

the insane except where their madness is marked off by lucid intervals), are 

null. And this must also be declared of the promises of the intoxicated, if 

intoxication has already gone so far that reason is plainly overpowered and 

stupefied. For it cannot be called a true and deliberate consent, if a man 

incline ever so much to an act by a momentary and unconsidered impulse, or 

give signs under other circumstances indicative of consent, at a time when 

the mind has been, as it were, displaced by some drug. Moreover it would be 

shameless to exact the fulfillment of such a promise, especially if 

involving a great burden. Again, if a man lay in wait for such intoxication, 

and observing the other's complaisance, cunningly extracted a promise, he 

will not be immune even from the charge of trickery and fraud. But whoever, 

after shaking off his intoxication, has confirmed his acts during that 

state, will certainly be obligated, not on the score of what he did when 

drunk, but of what he did when sober.



11. As for children, how long weakness of reason, hindering them from 

contracting an obligation, lasts in their case, cannot, in general, be very 

accurately defined, since in some judgment matures more quickly, in others 

more slowly. But that must be judged by the daily actions of each child. And 

yet in most states civil laws have established here a certain limit of time. 

So also in some places it is a salutary custom, that in contracting 

obligations infants must employ the authorization of more prudent persons, 

until the rash impulsiveness of youth is thought to have cooled off. For 

that age, even when it understands the business in hand, is generally 

carried away by a strong and short-sighted impulse, and is easy in making 

promises, hopeful, seeking a reputation for liberality, prone to interested 

friendships, and unacquainted with distrust. Hence he is scarcely to be 

acquitted of trickery, who takes advantage of that easy-going age, and 

wishes to enrich himself by the losses of others, which they, on account of 

feeble judgment, know not how to foresee or to estimate.



12. Consent is further hindered by an error. With regard to this, these 

rules must be observed: (1) When in a promise I have supposed anything as a 

condition, without reference to which I should not have promised, naturally 

the promise will have no force. For the promisor agreed not absolutely, but 

on a condition; and this not being realized, the promise too is null. (2) If 

I was led to agree or contract in consequence of an error, and I shall 

discover it while the matter is still intact and nothing has as yet been 

performed, it will certainly be equitable to allow me the opportunity to 

repent; especially if, in entering the agreement, I have openly declared the 

reason impelling me thereto, and if the other suffers no loss from my change 

of mind, or I am ready to make it good. But when the matter is no longer 

untouched, and the error becomes known only after the agreement has been 

fulfilled in whole or in part, the man who was mistaken cannot withdraw from 

his agreement, except in so far as the other is willing out of humanity to 

indulge him. (3) When an error has arisen in regard to the very thing which 

was the object of the agreement, the latter is vitiated, not so much on 

account of the error, as because the terms of the agreement were not 

satisfied. For in agreements the object in regard to which they agree, and 

its qualities, ought to be known, without which knowledge clear consent is 

unintelligible. Hence, on the discovery of a defect, the man who would have 

been injured can either withdraw from the contract, or compel the other to 

make good the defect, or even to pay the difference, when trickery or a 

fault on his part was involved.



13. But if a man was induced by the other's trickery and malicious fraud to 

promise or contract, we must hold these principles: (1) If a third person 

has employed guile, without collusion of the contracting party, the matter 

will stand; but from him who employed guile we shall be able to demand what 

we should have gained, if we had not been deceived. (2) If a man by guile 

has given me occasion to promise him something, or make some agreement with 

him I am not bound to him at all in consequence of that act (3) If a man 

shall enter into an agreement voluntarily and with evident intention, but 

still guile shall appear in the affair itself, for instance, in regard to 

the object, or its qualities and value, the agreement will be defective, so 

much so, that it is within the discretion of the deceived party to dissolve 

it entirely, or to demand compensation for the damage. (4) Matters not 

essential to the affair, and not expressly mentioned, do not vitiate an 

agreement otherwise made in due form, even though one of the parties may 

have made a tacit assumption while contracting, or his belief may have been 

cunningly confirmed, until the contract should be concluded.



14. Fear, as involved in promises and agreements, is understood in two 

senses: either as a plausible suspicion, that we may be deceived by the 

other, either because such a defect is inherent in his mind, or else because 

he has shown quite clearly his malicious intention ; or, in the second 

place, as great terror, arising from the threat of serious harm, if we are 

unwilling to promise, or to enter the agreement. With regard to the former 

kind of fear we must understand: (1) That whoever trusts the promises and 

agreements of a man whose honor is in general worthless, acts imprudently to 

be sure; but that an agreement is not made void by that sole cause. (2) When 

the agreement has been once entered into, and no new indications come to 

light of a deception aimed at us, it will not be open to us to withdraw from 

the agreement, on the pretext of defects which were recognized before it was 

made. For a reason which did not prevent a man from contracting, ought not 

to prevent him from fulfilling his contract. (3) When after the agreement 

has been entered very evident indications come to light, that the other man 

plans to cheat me, after I have first done my part, then I cannot be 

compelled to do so, until security has been given me against that deception.



15. With regard to the other species of fear, these rules are to be 

observed: (1) Contracts entered into on account of fear inspired by a third 

party are valid. For in this certainly no defect is involved, to prevent the 

other man from getting his rights under the contract as against me, and he 

certainly deserves compensation for having removed the fear inspired by the 

third party. (2) Contracts entered into from fear of, or respect for, 

legitimate authority, or through deference to those to whom we are under 

great obligations, are valid. (3) Contracts into which a man is unjustly 

forced by the very person to whom he gives the promise, or with whom he 

contracts, are invalid. For the injury which he inflicts upon me by 

inspiring an unjust fear, renders him incapable of claiming his rights 

against me under the agreement. And since one is otherwise bound to make 

good a loss occasioned by himself, therefore, if what should have been at 

once restored, is not paid, then the obligation is annulled by the 

counter-claim.



16. Furthermore, consent should be mutual, not only in contracts, but also 

in promises, so that both promisor, and promisee, must consent. For when the 

consent of the latter is lacking, or when he has refused to accept the 

offered promise, the thing promised remains in the hands of the promisor. 

For he who offers something of his own to another, neither wishes to obtrude 

it upon him against his will, nor to consider it ownerless. Hence, if the 

other does not accept it, the right of the promisor over the thing offered 

is undiminished. But if there was a previous request, it will be held to 

continue, unless expressly recalled; and in that case acceptance is 

understood to have taken place in advance, provided the offer corresponds to 

the request. For if there is a discrepancy here, an express acceptance is 

required, since often my interests are not served, unless I receive the 

amount for which I asked.



17. As for the subject-matter of promises and agreements, it is required 

that what we promise or agree to, be not beyond our powers, and that we be 

not forbidden by some law to perform it. For otherwise we are making either 

a foolish or a criminal promise. It follows then that no one can bind 

himself to what is for him impossible. If, however, a thing considered 

possible at the time of entering the agreement, has later by some chance 

become impossible, for no fault of the contractor, if nothing has yet been 

done, the contract will be void. If anything has been already done by the 

other, it must be restored, or an equivalent repaid. If even this is 

impossible, the greatest pains must be taken, that the other suffer no loss. 

For in contracts we have regard primarily to that upon which there was 

express agreement. When we cannot obtain this, it suffices if an equivalent 

is furnished. At least we must by all means take care that we experience no 

loss. But a man who, by guile or serious fault, has diminished his own 

powers of performance, is not only bound to make the utmost efforts, but can 

be punished into the bargain, to make good, as it were, any deficiency.



18. It is clear also that we cannot be bound to perform anything unlawful. 

For no one can effectively put himself under an obligation beyond his own 

power. But he who by a law forbids an action, of course takes away the power 

of undertaking it, and of accepting an obligation to perform it. For it 

would be a contradiction, to be bound absolutely under an obligation 

confirmed by the laws to do something forbidden by the same laws. Hence he 

who promises unlawful acts is guilty; twice guilty he who performs such 

promises. From which we further conclude that promises which will be 

injurious to him for whom they are made, ought not to be kept; since it is 

forbidden by the natural law to cause harm to another, even if he foolishly 

desires it. If then an agreement concerning a shameful thing has been 

entered into, neither party will be bound to perform it. In fact, even when 

the shameful deed has been committed by one of them, the other will not be 

bound to pay the wages agreed upon. But whatever has already been given with 

such a motive, cannot be recovered, unless trickery or extraordinary damage 

may be involved.



19. Finally, it is also clear that promises or agreements affecting things 

belonging to others are void, in so far as these are subject not to our 

direction and will, but to those of another. But if I promise to exert 

myself to have the other perform something (presupposing that I cannot 

command him by authority), then, by every means morally possible (i.e., in 

so far as the other can ask it of me honorably, and regard for the civil 

life permits), I am bound to use my efforts to persuade him to do his part. 

Moreover, as regards things or actions of mine, to which another has by this 

time acquired a right, I cannot make a valid promise to a third person, 

except with a view to the possibility that the other's right may expire. For 

one who by previous promises or agreements has already transferred his right 

to another, certainly has no longer any right left, such as he can confer 

upon a third person. And it would be no trouble to void all promises and 

agreements, if it were permitted to enter upon another, which made contrary 

dispositions and could not be fulfilled at the same time with the previous 

agreement. Upon this Tests the old saying, "First in time, first in right."



20. With regard to promises it is further to be particularly observed, that 

they are usually made either simply and absolutely, or under a condition, 

that is, the validity of the promise is attached to some occurrence 

depending upon chance or the will of man. Now conditions arc either possible 

or impossible. The former are subdivided into the casual or fortuitous, the 

existence or non-existence of which is not in our power; discretionary or 

arbitrary, the existence or non-existence of which is in the power of him to 

whom the promise is given; and mixed, the fulfillment of which depends 

partly upon the will of him to whom the promise is given, and partly upon 

chance. The impossible conditions are such either physically or morally, 

that is, some things cannot in the nature of things be done, and some ought 

not to be, as contrary to laws and morality. And impossible conditions, if 

we follow the natural and simple interpretation, negative the language of a 

promise. And yet, legally speaking, it is possible, in case they have been 

added in some serious affair, to regard them as non-existent, that men may 

not be mocked by agreements which can have no outcome.



21. Finally, we promise and contract, not only of ourselves, but also 

through the intervention of other men, whom we have ourselves appointed as 

go-betweens and interpreters of our will. And when they in good faith have 

done what was contained in our instructions, we are under a valid obligation 

to such persons as have dealt with them as our representatives.



22. Such are the absolute duties of man, as also those which serve as a 

transition to the other kind. The rest presuppose either some human 

institution, based upon a universal convention, and introduced among men, or 

else some particular form of government. Of such institutions we observe in 

particular three: language, ownership and value, and human government. We 

must next explain each of these, together with the resulting duties.