Different Kinds of Law and Explanation When It Is Lawful to Wage War

Grotius justifies the right to wage a just war in several ways. His general con­cept of war is, meanwhile, rather broad. He defines it as �the condition of those contending by force' (status per vim certantium qua tales sunt) (ibp, 1.1.2.1).

According to Grotius, to wage war is compatible with natural law (ibp, 1.2.1). In making this claim, Grotius appeals to Cicero and the Stoics and their dis­tinction between the first and second principles of nature. War is not incom­patible with the first principles of nature, because

[t]he end and aim of war being the preservation of life and limb, and the keeping or acquiring of things useful to life, war is in perfect accord with those first principles of nature. If in order to achieve these ends it is necessary to use force, no inconsistency with the first principles of nature is involved, since nature has given to each animal strength sufficient for self-defense and self-assistance.

ibp, 1.2.1.4

All animals share the principle of self-preservation. When preservation of this principle is threatened, the animal, both human and non-human, has the right to use force to defy the aggressor and to protect its body.^[685]

Nor does war violate the second principle of nature, which is �right reason':

Right reason... and the nature of society... do not prohibit all use of force, but only that use of force which is in conflict with society, that is which attempts to take away the rights of another. For society has in view this object, that through community of resource and effort each individ­ual be safeguarded in the possession, of what belongs to him.

ibp, 1.2.1.5

War is caused by violation of law and its purpose is to renew the rule of law. In other words, war is an abnormal state of affairs and its goal is to restore peace. A just war can be waged on the basis of either of the following three causes: as defense against unexpected attack, in order to recover property, or as a puni­tive war (ibp, 11.1.2.1-2).

To wage war is not in contradiction with the law of nations, either. According to Grotius, this is apparent from the â€?histories, and the laws and customs of all peoples'. This holds for wars in general, but â€?a definite formality in the conduct of war was introduced by the law of nations, and... particular effects follow [for] wars waged in accordance with such formality under the law of nations' (iBP, 1.2.4.2). Grotius deals with these â€?formalities' at length in Book ιιι of his treatise, listing as examples of acts that contradict the law of nations killing by poison, (ibp, 111.4.15), employment of assassins (iBP, 111.4.18), rape (iBP, 111.4.19), etc.

In some instances, the rules of natural law and the law of nations are mutu­ally incompatible. That does not mean, however, that the law of nations is unjust. For instance, no one is a slave by nature (ibp, 11.23.11) but according to the law of nations, all persons captured in war become slaves (ibp, 111.1). That, according to Grotius, applies especially to antiquity and less civilized nations. Among Christians, however, �those who are captured in a war which has arisen among themselves do not become slaves so as to be liable to be sold, constrained to labour, und suffer the fate of slaves in other respects', and a similar law holds among �Mohammedans among themselves' (ibp, 111.7.9).

Grotius goes on to demonstrate in some detail that waging a war does not violate the divine volitional law either. First, he responds to a possible objec­tion that natural law is immutable, which could be taken to imply that God cannot posit anything that would be incompatible with it.

First, Grotius cites the law which Noah and his descendants received from God. It forbids the spilling of blood among people (Genesis 9:5-6). The sphere of application of this Noahic law is the same as that of the injunction �Thou shalt not kill!' from the Ten Commandments, as demonstrated by the fact that it does not prevent capital punishment or wars. Grotius explains it as follows: The latter rule of law then, as well as the former, had in view not so much the ordaining of something new as the declaration and repeti­tion of a rule of the law of nature which had been effaced by degener­ate usage. Hence these words are to be taken in a sense which conveys the idea of a moral fault, just as by the word homicide we understand not the slaying of a man in general, but a premeditated murder of an innocent man. What follows in regard to the shedding of blood in turn seems to me to contain not a statement of a bare fact, but a provision of law.

IBP, I.2.5.2

Similarly, according to Grotius, the New Testament permits war. Grotius sup­ports this claim by quotations, the most important of which is from Paul's Epistle to the Romans (Romans 13:4): �For he is a minister of God to thee for good. But if thou do that which is evil, be afraid, for He beareth not the sword in vain. For he is a minister of God, an avenger for wrath to him that doeth evil'. Grotius interprets this claim to mean that

By the right of the sword through a figure of speech every form of com­pulsion is understood, as also sometimes in the writings of the jurists; but in such a way, nevertheless, that the right to impose the extreme penalty, that is the actual use of the sword, is not excluded.

IBP, I.2.7.2

This may be taken to indicate that Grotius's considerations upon divine volitional law and its relation to just war bring nothing new in comparison to a parallel justification with respect to the law of nature and the law of nations. Biblical passages can be interpreted as implicit demands of natural law and Grotius seems aware of it. One could thus conclude that Grotius's layout of the system of laws would function equally well without volitional divine law, although he, a God-fearing Calvinist, was not ready to take such step. Grotius's system of laws is also remarkably tolerant of other religions. Unlike Suarez, for instance, Grotius hardly ever mentions heretics.^[687]

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