§ 3. If now we turn again to the political question, from which we diverged, we see that we have obtained from the preceding discussion one of the criteria of the justice of laws which we were seeking--viz. that they must avoid running counter to natural and normal expectations--: but we see at the same time that the criterion cannot be made definite in its application to private conduct, and it is easy to show that there is the same indefiniteness and consequent difficulty in applying it to legislation. For Law itself is a main source of natural expectations; and, since in ordinary times the alterations in law are very small in proportion to the amount unaltered, there is always a natural expectation that the existing laws will be maintained: and although this is, of course, an indefinite and uncertain expectation in a society like ours, where laws are continually being altered by lawful authority, it is sufficient for people in general to rely upon in arranging their concerns, investing their money, choosing their place of abode, their trade and profession, etc. Hence when such expectations are disappointed by a change in the law, the disappointed persons complain of injustice, and it is to some extent admitted that justice requires that they should be compensated for the loss thus incurred. But such expectations are of all degrees of definiteness and importance, and generally extend more widely as they decrease in value, like the ripples made by throwing a stone into a pond, so that it is practically impossible to compensate them all: at the same time, I know no intuitive principle by which we could separate valid claims from invalid, and distinguish injustice from simple hardship.[210] But even if this difficulty were overcome further reflection must, I think, show that the criterion above given is incomplete or imperfectly stated: otherwise it would appear that no old law could be unjust, since laws that have existed for a long time must create corresponding expectations. But this is contrary to Common Sense: as we are continually becoming convinced that old laws are unjust (_e.g._ laws establishing slavery): indeed, this continually recurring conviction seems to be one of the great sources of change in the laws of a progressive society. Perhaps we may say that there are natural expectations which grow up from other elements of the social order, independent of and so possibly conflicting with laws: and that we call rules unjust which go counter to these. Thus _e.g._ primogeniture appears to many unjust, because all the landowner’s children are brought up in equally luxurious habits, and share equally the paternal care and expenditure, and so the inequality of inheritance seems paradoxical and harsh. Still, we cannot explain every case in this way: for example, the conviction that slavery is unjust can hardly be traced to anything in the established order of the slave-holding society, but seems to arise in a different way.