Hugo Grotius (b. 10 April 1583 – d. 28 August 1645) is often credited with laying the foundations for international law based on a theory of natural law. However, while he is frequently regarded as the founder of international law, this "both ignores the contributions of his predecessors and reads back into his work ideas that belong to a later period" (Brown et al., p.325). Grotius first achieved fame as a poet and later for writing The Law of War and Peace (1625) in which he presents, in embryo, a powerful theory of international justice.
Hugo Grotius
Hugo Grotius

Summary of reading

Online text: The Laws of War and Peace, Lonang Library edition.


Grotius' intention is to discuss the body of law concerned with the mutual relations among states or rulers of states.

Grotius argues against those who say that there is no natural law. Carneades, who Grotius uses as a pleader against justice, argues that "for reasons of expediency, men imposed upon themselves laws, which vary according to customs, and among the same peoples often undergo changes as times change; moreover that there is no law of nature, because all creatures, men as well as animals, are impelled by nature toward ends advantageous to themselves; that consequently, there is no justice, or, if such there be, it is supreme folly, since one does violence to his own interests if he consults the advantages of others" (The Law of War and Peace, in Brown et al., p. 326).

Grotius argues against this, saying that human beings are a different kind of animal from other animals, that humans desire a peaceful and organised social life, and that, therefore, it can't be a universal truth that human beings are impelled by nature to only pursue their self-interests.

Just as some animals put the good of their offspring before themselves, and children have a natural disposition to help others, so too do mature men act this way, in the knowledge that they have a special gift of speech and knowledge. (This is not exactly what Grotius says in The law of War and Peace (see Brown et al., p. 326.)

Maintenance of social order is the source of (natural) law.

Because man has a strong bent towards social life and the power to decide what is good, this means that the nature of man follows to a well-tempered judgment, i.e. human beings act rationally, not wanting to be lead astray by rash impulses etc. Anything that is at variance with human rationality is also contrary to the law of nature (i.e., to the nature of man).

This leads to our exercise of judgment; i.e the propensity to give preference to helping kinsmen over strangers, the poor over the rich. Long ago this kind of judgment was thought to be part of the law, now law is understood to be more based on leaving to another that which belongs to him or fulfilling obligations to him. (NB: Grotius's focus here in regard to the social inclination of human beings is not on benevolence and working together, but on autonomous individuals not harming each other)

Grotius argues that these facts would be true without God, but that God is the all powerful creator and we owe all to Him.

Another source of law is freewill of God. Law of nature, relating to the social life of man also stems from God.

God has made our fundamentally good traits more clear.

Rule of nature to abide by pacts, from this municipal law and its bodies stems.

Nature of man (leading us into mutual relations in society.)

Law of nature

Obligation which arises from mutual consent

Municipal law

Law not founded on expediency alone. No state so powerful that it won't at some point need alliances with other states.

If no association of men can be maintained without law (Aristotle) then surely association which binds together the human race, i.e. states, needs laws.

War ought not to be undertaken except for the enforcement of rights, and once undertaken
it should be carried only within the bounds of law and good faith.

Judgments are effective against those who feel they are too weak to resist, and wars are undertaken for those who are equally strong or think they are.

For wars to be justified, they must be carried out with no less scrupulousness than judicial proceedings are to be.

The law which is valid amongst nations is valid for war and in war. In the Christian world, many men have acted in a frenzied and barbarous way in war, but a middle ground must be struck between nothing justifying war, and everything justifying war.

Part of Grotius proof for the law of nature comes from the testimonies of philosophers, historians, poets and orators. But his basis (word choice? - xmarquez xmarquez Sep 10, 2007) is not just on testimonies, but on 'characters of the matter' i.e. anything which can't be deduced by a sure process of reasoning, but is clearly everywhere, must have originated from the free will of man (this part unclear - xmarquez xmarquez Sep 10, 2007)

Grotius argues that the Old Testament does not set forth the law of nature, but it can be a source of the law of nature as long as a distinction is made between the law of men (in relation to one another) and the law of God.

Book 1 Chapter 2 Whether is is lawful to wage war

That war is not in conflict with the law of nature is proved by several considerations.

Grotius sets out two principles of nature to test the legality of war:

  1. The principle of individual self-preservation i.e. idea that everyone desires their body to be in good order.
  2. The conformity of things with reason, which is superior to the body. Conformity with moral goodness becomes the principal object. 'Right reason ought to be more dear to us that these things through which instruments we have been brought to it.'

So in investigating the law of nature, it is necessary to see what is consistent with the fundamental principles of nature.

Theres is nothing in the first principle, of self-preservation, which opposes war since preservation and gain which are the ultimate motivators of war are in accordance with this first principle. The use of force is not inconsistent, since nature gives to each animal the strength sufficient for self-defence and self-assistance.

The second principle, concerning right reason and the nature of society, doesn't prohibit the use of force, only that which is in conflict with society and that which attempts to take away the rights of another.

Therefore it is not contrary to the nature of society to look out for one's own interests, provided the rights of others are not infringed on, and therefore the use of force which does not violate these rights of others is not unjust.

Study Questions

  • What is the source of natural law for Grotius?
Grotius defines the source of natural law as that of an inherent humanitarian morality as distinct from the lawlessness of 'nature' in its more conventional sense. He juxtaposes the condition of animalistic selfishness with the superior intellectual characteristics of man- in particular, man's desire for community and society. It is this 'sociableness' which is natural to human kind. Thus, natural law finds its source in the morality of humankind which is intrinsic to their aim of a social life. Human beings do not live as singular beings but in communities and it is the intelligence and the power of speech of the species which has led them to realise that their progress depends on social living and organization of a society. Grotius refers to the conscience of children to illustrate that natural law, i.e.: morality, is indeed an inherent characteristic of human beings which can be translated into general principles for governing society and inter-state relations.
  • Is law possible in the absence of sanctions?
Grotius believed that though a law without a corresponding sanction would have a lesser degree of effectiveness, but it would still have some weight.
  • What is the basis of the law of nature? How do we know the law of nature?
Natural law is a universal, rational, objective standard of right and wrong. The basis of the law of nature is the natural inclination towards self preservation inherent in every human. Grotius comes to this foundation for his philosophy through looking for a principle common to ALL belief systems (a consensus based rather than dogmatic or relativistic approach). As a result of this approach he rejects existing civil law and scripture as possible basis' for finding his natural law. Only natural law "derived from universally valid premises" possesses the required generality.

Grotius says that Stoics and other philosophical schools of antiquity agree on the primacy of self-preservation. Even Skeptics acknowledge the need to preserve oneself, so this is the "indisputable foundation for morality".

Why is this moral? Because if the desire for survival is inherent in human nature, no one can be judged for acting on it. From this stem two principles of natural law; it is permissible to defend one's own life, and it is permissible to acquire things useful for this life.

However Grotius' individualistic premises are not extreme. He believes in a natural kinship between humans, making it reasonable to demand that we refrain from hurting each other. This means that we may not; physically harm each other unnecessarily, nor seize each others' possessions. These implications are still minimal - humans have no obligations to assist one another, no duties of beneficence, they merely must practice a mutual non-interference.

Two legacies on modern political thought from Grotius' thinking on natural law are:
  1. that civil society is an artificial construction, which is made by individuals who have natural rights which are non civil.
  2. People have rights, and civil law exists to protect these rights. Governments who contravene these natural rights are illegitimate.
  • How does Grotius differ from Hobbes on the status of natural law?
Grotius argues that natural law is a series of rules which enable human beings to live together in harmony. This follows from his idea that man is a social as well as a reasonable being. This differs from Hobbes' theory that man is in a natural state of war and as always looking out for number one. Hobbes argues that man is simply rational and will do whatever is necessary to survive, rather than the emphasis on 'sociableness' that Grotius refers to. (Could be expanded/explained better - xmarquez xmarquez Sep 10, 2007)
  • How does Grotius differ from the Stoics on law?
Brown et al. (pp. 311-312) state that “international law is one of the outcomes of an intellectual effort to reconstruct the Stoic/Christian universal human community as a community of territorial states.”

As Brown et al. (p. 28) write, "Stoics were convinced that the universe was an ordered whole, amenable to rational explanation and proceeded so to explain it. The central human faculty, which allowed us to reason, think, and speak – the logos – is embodied in the universe. Humans and nature are thus one in the logos. If humans recognize this, they will act in ways wholly congruent with human rationality at its best. Of course, in order to do this humans must know how the universe is constructed and how you can reason. Hence the importance of natural philosophy and logic for Stoicism."

Stoics believe that “there is a divine and natural law governing everything in the universe, including human conduct” (Brown et al., p. 312). “In the Christian version of this view, the law is divine in being promulgated by God and natural in being knowable by reason without the aid of revelation” (ibid). “Because human beings are free, rational beings, they can choose to disobey this law” [i.e., divine and natural law] (ibid.). Natural law is “understood as a morality binding on all human beings … [and] must be distinguished from the laws observed in particular communities” (ibid.). The conception of morality as natural law “goes back through Aquinas to the Stoic view that all human beings are citizens not only of a particular polis with its own local laws but of an ideal universal community: a ‘cosmopolis’ whose law is this rationally knowable natural law. There are, in other words, objective, universal, and eternal standards of right and wrong by which human laws as well as human conduct are to be judged” (ibid.).

Grotius believes that only “natural law – which consists of moral principles correctly derived from universally valid principles – possesses the required generality” (Brown et al., p. 313). That is, for Grotius, civil law and Holy Scripture were not adequate as a source of universal moral principles. Grotius embraces the Stoic notion of a universal law of nature because he considers that what Stoicism and the other ancient philosophical standpoints concur on must be true. And, in this regard, all the ancient philosophical traditions agree (including the Skeptics) that self-preservation is pre-eminent, which, for Grotius, implies “the indisputable foundation for morality” (ibid., pp. 313-314). Moreover, “the very nature of man, which even if we had no lack of anything would lead us into the mutual relations of society, is the mother of the law of nature” (from The Law of War and Peace, in Brown et al., p. 328).
  • How is Grotius similar or different from medieval thinkers on the justification of war?
  • What are the differences between the law of nature, the law of nations, and municipal law?
For Grotius, the law of nature is the idea that humans are not completely self-interested and out to seek only their own good; but that they have a desire for society and the social life. This social life is "peaceful and organized according to the measure of his [each person's] intelligence, with those who are of his own kind". The law of nature also includes the fact that unlike other animals, humans have a power of discrimination which makes us tell what is wrong and right, and "whatever is clearly at variance with such judgement (eg. wrong) is understood to be contrary also to the law of nature, that is, to the nature of man".
Municipal law comes from the law of nature, as because the law of nature makes humans social and gives them the want to abide by pacts, it is natural that municipal law arises. Municipal law is the obligation which comes from mutual consent; "and since this obligation derives itf force from the law of nature, nature may be considered, so to say, the great-grandmother of municipal law". In other words, municipal law is the idea that people are loyal to people they have a connection with.
Just as each state has state laws that are advantageous to the state, it makes sense that such laws have arisen between all states or a large group of states, and this is the law of nations. The law of nations is the idea that just as state laws benefit the state, the law of nations can benefit all or many states. Grotius believes that all states should abide by the law of nations, because "the state which trangresses the laws of nature and of nations cuts away also the bulwarks which safeguard its own future peace", that is to say states which do not abide are doing themselves future harm, as "no state is so powerful that it may not some time need the help of others outside itself".
  • How is the law of nations possible?
  • What is Grotius' critique of Erasmus? What is Grotius trying to accomplish?
He agrees partly with Erasmus' theory that war should never be undertaken to settle disputes but he still believes it is justifiable in order to enforce rights (Not sure this is what Grotius' explanation. A quotation or citation would help - xmarquez xmarquez Sep 10, 2007). He also believes that Erasmus' theory is too extreme because it requires all Christians to lay down their arms, which he believes will end up causing more harm than good (why? - xmarquez xmarquez Sep 10, 2007). Thus he is attempting to take a sort of middle ground without pushing too hard in a particular direction as he puts it. (unclear - xmarquez xmarquez Sep 10, 2007)
  • Does Grotius' description of justified causes of war and justified conduct in war impose any meaningful restraints on states?

External Resources

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Select bibliography

  • Steven Forde. 1998. "Hugo Grotius on Ethics and War." The American Political Science Review, Vol. 92, No. 3, pp. 639-648. Link.
Abstract: Interest in the thought of Hugo Grotius on international law and ethics is justified inasmuch as he attempted to define a theoretical position between an idealism he thought counterproductive and an amoral realism he found unacceptable. Grotius constructed a system in which the moral authority of natural law was combined with the flexibility of human law. This required him to develop a special understanding of the nature and relation of these two types of law. In giving the law of nations, as a product of human will, the authority to suspend provisions of natural law, he provided for a code of international conduct that could permit injustice where necessary, without abandoning moral ideals altogether.
  • Knud Haakonssen. 1985. "Hugo Grotius and the History of Political Thought." Political Theory, Vol. 13, No. 2., pp. 239-265.