There is one case and one only in which a contract is not binding, either on the state or on the private individual, and that is when the signatory was forced to enter upon it with a knife at his throat. Obligations which a victor imposes on his defeated and disarmed opponent are by their very nature invalid. The old cry of Brennus: "Vae victis!" is might and cannot constitute a right. Civil law calls this kind of thing compulsion and decrees that it invalidates any contract. Only a pedantic mind, stupid and depraved, immersed in hair-splitting trickery and incapable of a straight thought, could complacently maintain in the face of all common sense that might and compulsion, far from doing away with right, are the source of all right. The silly formula coined for this is: "Might is right." Might may be a fact, but it is not right. The source of right is not might but Morality, which might disavows and destroys. The necessary condition of any obligation which is to be valid is freedom. Kant proved this, but his proof was unnecessary, for it is self-evident. A forced treaty is no treaty, for it is the victor's fist which has guided the hand of the vanquished, and it is he who wrote the latter's signature under the document. The will, the consciousness of the seeming signatory were absent at the time.
But the worst and most immoral action of the state, beside which a breach of treaty for selfish reasons pales to insignificance, is the war of aggression for purposes of profit, that is, for the conquest of territory, extortion of money, increase of power, or fame. War is the quintessence of all crimes against life and property, against the body and mind of a person, the prevention of which is the aim and object of all Morality and all laws derived from it. Any means are permissible whereby this wickedness may be prevented; the war of defence, waged by the party attacked, is not only justified but sacred, as are the functions of the institutions that society has developed to hunt down and punish those who do not respect Morality and Law. And just as it is the duty of every society to maintain courts of justice, police and prisons, so it is the duty of every state to be well armed, well versed in the use of weapons and strong, so long as it must count on the fact that there are practical politicians who do not recognize Morality as binding the state, and nations that are ready on the first hint of their leaders to perpetrate every crime that conscience, the Ten Commandments and penal law forbid.
It is idle, in my opinion, to discuss the question whether war will ever disappear from the world. It serves no purpose to contradict those who declare it to be eternal. It is possible that it will continue to exist as long as there is vice, sin and crime; and I do not believe that these will ever be completely exterminated. Among mankind there will probably never be a lack of sick and depraved people whose selfishness is monstrously exaggerated, whose instincts urge them with stormy violence, whose powers of inhibition are scantily developed or altogether wanting, who suffer from anæsthesia of the feelings and are therefore incapable of any sympathy with their fellow men and who are mentally too weak to foresee the results of their actions. Individuals of this kind are born criminals whose existence society will probably never be able to prevent and against whom it is obliged to protect itself. Now war arises from the same psychic conditions as the antisocial actions of these born criminals, and therefore the pessimists may be right in maintaining that it can never be abolished. But it is one thing to assert the existence of a deplorable fact and quite another to glorify it. To say that war is a part of the universe constituted by God is blasphemy, even though the saying emanates from Moltke. To extol war ecstatically and to sing hymns of praise to it, to declare that it evokes the highest virtues of man is a panegyric of crime, a thing anticipated and punishable in the penal code.
I am not here attempting to solve the problem of what practical measures can be taken whereby right may be set in the place of might in inter-state relations, and instead of ruthless selfishness, Morality, that is, self-control, consideration and respect for the just claims of one's fellow men and love of one's neighbour. That is as far beyond the scope of this work as is the investigation of the methods of education, criminal justice, police organization or prison conditions intended to deal with the tide of crime and to stem it as far as possible. I am concerned with moral philosophy, and from that point of view I show that all Morality is rooted in the desire of men to live together peaceably in a society, to have greater security of life and property, greater possibilities of happiness, and that the same needs must impose the rules of Morality upon states in their relations to one another. According to Hobbes the primitive condition of mankind is that of a war of every man against all other men, and only the creation of society makes an end of it. But if the state unleashes the dogs of aggressive warfare it hurls mankind back into its primitive condition and destroys the work it was created to do. The Stoic Seneca says: "Homo sacra res homini," "Man is sacred to man." The practical politicians who praise war repeat with Hobbes: "Homo homini lupus," "Man is a wolf to man." The moral man demands a return from Hobbes to Seneca. If it has been possible in the state to tame the wolfish instincts of the individual and to make him bow down before Custom and Law, it must be equally possible to do so in the relations of states to one another. He who denies this in principle disavows Morality altogether, not only for the state but also for the individual; he who admits it in principle but in practice scornfully disregards it is a bandit, and it is desirable to treat him like any other robber and murderer who, to satisfy his wolfish appetites, tramples on Morality and Right and acts like a wild beast.
To this, however, the Moralist will object sadly, and the practical politician with scornful superiority, that the state has created institutions for suppressing the bandit, but that there are none such to control bandit states, and that self-defence alone, the only means of self-protection for man in Hobbes's primitive condition, can gain a footing between them. Clearly only the party attacked is in a state of self-defence, but the bandit who has a sufficient sense of humour to play the pettifogging lawyer can always maintain that attack is also self-defence, the preventive form of self-defence. The answer to this is: if society has managed to provide judges and police in order to secure peace, then mankind will for the same purpose learn how to provide courts of justice and a police force to deal with the bandits of practical politics who endanger peace among nations. But that is a practical question, not a theoretical one, not a principle of moral philosophy. The latter shows irrefutably that there is only one Morality, not a private one and a public one which is its negation, not one kind for the individual and another for politics, for the state.
He who defends the thesis of a twofold Morality merely shows that he does not possess simple Morality.