Further, we include under the idea of binding engagements not merely verbal promises, but also what are called ‘implied contracts’ or ‘tacit understandings.’ But this latter term is a difficult one to keep precise: and, in fact, is often used to include not only the case where _A_ has in some way positively implied a pledge to _B_, but also the case where _B_ has certain expectations of which _A_ is aware. Here, however, the obligation is not so clear: for it would hardly be said that a man is bound to dispel all erroneous expectations that he may know to be formed respecting his conduct, at the risk of being required to fulfil them. Still, if the expectation was such as most persons would form under the circumstances, there seems to be some sort of moral obligation to fulfil it, if it does not conflict with other duties, though the obligation seems less definite and stringent than that arising out of contract. Indeed I think we may say that Justice is generally, though somewhat vaguely, held to prescribe the fulfilment of all such expectations (of services, etc.) as arise naturally and normally out of the relations, voluntary or involuntary, in which we stand towards other human beings. But the discussions in the preceding chapter have shown the difficulty of defining even those duties of this kind which, in an indefinite form, seemed certain and indisputable: while others are only defined by customs which to reflection appear arbitrary. And though while these customs persist, the expectations springing from them are in a certain sense natural, so that a just man seems to be under a kind of obligation to fulfil them, this obligation cannot be regarded as clear or complete, for two reasons that were given in the last chapter; first, because customs are continually varying, and as long as any one is in a state of variation, growing or decaying, the validity of the customary claim is obviously doubtful; and secondly, because it does not seem right that an irrational and inexpedient custom should last for ever, and yet it can only be abolished by being “more honoured in the breach than in the observance.”
This line of reflection therefore has landed us in a real perplexity respecting the department of duty which we are at present examining. Justice is something that we conceive to be intrinsically capable of perfectly definite determination: a scrupulously just man, we think, must be very exact and precise in his conduct. But when we consider that part of Justice which consists in satisfying such natural and customary claims as arise independently of contract, it seems impossible to estimate these claims with any exactness. The attempt to map out the region of Justice reveals to us a sort of margin or dim borderland, tenanted by expectations which are not quite claims and with regard to which we do not feel sure whether Justice does or does not require us to satisfy them. For the ordinary actions of men proceed on the expectation that the future will resemble the past: hence it seems natural to expect that any particular man will do as others do in similar circumstances, and, still more, that he will continue to do whatever he has hitherto been in the habit of doing; accordingly his fellow-men are inclined to think themselves wronged by his suddenly omitting any customary or habitual act, if the omission causes them loss or inconvenience.[209] On the other hand, if a man has given no pledge to maintain a custom or habit, it seems hard that he should be bound by the unwarranted expectations of others. In this perplexity, common sense often appears to decide differently cases similar in all respects, except in the quantity of disappointment caused by the change. For instance, if a poor man were to leave one tradesman and deal with another because the first had turned Quaker, we should hardly call it an act of injustice, however unreasonable we might think it: but if a rich country gentleman were to act similarly towards a poor neighbour, many persons would say that it was unjust persecution.