§6. We have still to examine (whether as a branch of Justice or under a separate head) the duty of fulfilling express promises and distinct understandings. The peculiar confidence which moralists have generally felt in this principle is strikingly illustrated by those endeavours to extend its scope which we have just had occasion to notice: and it certainly seems to surpass in simplicity, certainty, and definiteness the moral rules that we have hitherto discussed. Here, then, if anywhere, we seem likely to find one of those ethical axioms of which we are in search. Now we saw that the notion of a Promise requires several qualifications not commonly noticed to make it precise: but this alone is no reason why it may not be fitly used in framing a maxim, which when enunciated and understood will properly claim universal acceptance as self-evident. For similarly the uninstructed majority of mankind could not define a circle as a figure bounded by a line of which every point is equidistant from the centre: but nevertheless, when the definition is explained to them, they will accept it as expressing the perfect type of that notion of roundness which they have long had in their minds. And the same potential universality of acceptance may, I think, be fairly claimed for the propositions that the promise which the Common Sense of mankind recognises as binding must be understood by promiser and promisee in the same sense at the time of promising, and that it is relative to the promisee and capable of being annulled by him, and that it cannot override determinate prior obligations.
But the case is different with the other qualifications which we had to discuss. When once the question of introducing these has been raised, we see that Common Sense is clearly divided as to the answer. If we ask (e.g.) how far our promise is binding if it was made in consequence of false statements, on which, however, it was not understood to be conditional; or if important circumstances were concealed, or we were in any way led to believe that the consequences of keeping the promise would be different from what they turn out to be; or if the promise was given under compulsion; or if circumstances have materially altered since it was given, and we find that the results of fulfilling it will be different from what we foresaw when we promised; or even if it be only our knowledge of consequences which has altered, and we now see that fulfilment will entail on us a sacrifice out of proportion to the benefit received by the promisee; or perhaps see that it will even be injurious to him though he may not think so different conscientious persons would answer these and other questions (both generally and in particular cases) in different ways: and though we could perhaps obtain a decided majority for some of these qualifications and against others, there would not in any case be a clear consensus either way. And, moreover, the mere discussion of these points seems to make it plain that the confidence with which the ``unsophisticated conscience'' asserts unreservedly ``that promises ought to be kept'', is due to inadvertence; and that when the qualifications to which we referred are fairly considered, this confidence inevitably changes into hesitation and perplexity. It should be added, that some of these qualifications themselves suggest a reference to the more comprehensive principle of Utilitarianism, as one to which this particular rule is naturally subordinate.
Again, reflection upon the place of this duty in a classified system of moral obligations tends to confirm our distrust of the ordinary enunciations of Common Sense in respect of it. For, as was seen, Fidelity to promises is very commonly ranked with Veracity; as though the mere fact of my having said that I would do a thing were the ground of my duty to do it. But on reflection we perceive that the obligation must be regarded as contingent on the reliance that another has placed on my assertion: that, in fact, the breach of duty is constituted by the disappointment of expectations voluntarily raised. And when we see this we become less disposed to maintain the absoluteness of the duty: it seems now to depend upon the amount of harm done by disappointing expectations; and we, shrink from saying that the promise ought to be kept, if the keeping it would involve an amount of harm that seems decidedly to outweigh this.
The case of Veracity we may dismiss somewhat more briefly, as here it was still more easy to show that the common enunciation of the unqualified duty of Truth-speaking is made without full consideration, and cannot approve itself to the reflective mind as an absolute first principle. For, in the first place, we found no clear agreement as to the fundamental nature of the obligation; or as to its exact scope, i.e. whether it is our actual affirmation as understood by the recipient which we are bound to make correspondent to fact (as far as we can), or whatever inferences we foresee that he is likely to draw from this, or both. To realise perfect Candour and Sincerity, we must aim at both: and we no doubt admire the exhibition of these virtues: but few will maintain that they ought to be exhibited under all circumstances. And, secondly, it seems to be admitted by Common Sense, though vaguely and reluctantly, that the principle, however defined, is not of universal application; at any rate it is not thought to be clearly wrong that untruths should be told to children, or madmen, or invalids, or by advocates, or to enemies or robbers, or even to persons who ask questions which they have no right to ask (if a mere refusal to answer would practically reveal an important secret). And when we consider the limitations generally admitted, it seems still more plain than in the last case, that they are very commonly determined by utilitarian reasonings, implicit or explicit.