In other words, certain social needs and certain social utilities--which we can all recognise as indispensables--furnish a ground of agreement for the common action without which no society can be established. And the need for such a criterion becomes more manifest as we learn more of the wonderful fashion in which we sublimate our motives. A country refuses to submit its dispute to arbitration, because its 'honour' is involved. Many books have been written to try and find out precisely what honour of this kind is. One of the best of them has decided that it is anything which a country cares to make it. It is never the presence of coal, or iron, or oil, which makes it imperative to retain a given territory: it is honour (as Italy's Foreign Minister explained when Italy went to war for the conquest of Tripoli). Unfortunately, rival States have also impulses of honour which compel them to claim the same undeveloped territory. Nothing can prove--or disprove--that honour, in such circumstances, is invoked by each or either of the parties concerned to make a piece of acquisitiveness or megalomania appear as fine to himself as possible: that, just because he has a lurking suspicion that all is not well with the operation, he seeks to justify it to himself with fine words that have a very vague content. But on this basis there can be no agreement. If, however, one shifts the discussion to the question of what is best for the social welfare of both, one can get a _modus vivendi_. For each to admit that he has no right so to use his power as to deprive the other of means of life, would be the beginning of a code which could be tested. Each might conceivably have that right to deprive the other of means of livelihood, if it were a choice between the lives of his own people or others. The economic fact is the test of the ethical claim: if it really be true that we must withhold sources of food from others because otherwise our own would starve, there is some ethical justification for such use of our power. If such is not the fact, the whole moral issue is changed, and with it, to the degree to which it is mutually realised, the social outlook and attitude. The knowledge of interdependence is part, at least, of an attitude which makes the 'social sense'--the sense that one kind of arrangement is fair and workable, and another is not. To bring home the fact of this interdependence is not simply an appeal to selfishness: it is to reveal a method by which an apparently irreconcilable conflict of vital needs can be reconciled. The sense of interdependence, of the need of one for another, is part of the foundation of the very difficult art of living together.