Hugo Grotius is the originator of the system of philosophy of law which goes by the name of “natural law” and which for more than a century was the only one applied and cultivated; indeed, it was the only one held to be possible, because that which customarily was distinguished into various systems during this period (sociabilistic system, system of fear, external peace, etc.), was merely a particular implementation of one and the same system.
Principle of law
His work in which this is laid down, On the Law of War and Peace, had the law of nations [das Völkerrecht] as its intended and actual task. For this, the old foundations – feudal law, knightly battle customs, ecclesiastical orders and temperaments – had given way, and new ones needed to be laid; indeed the evidence had to be provided that in relationships among sovereign states and especially in war, not merely advantage and violence applied, but justice. But standards to legislate and enforce among sovereign states over which no supreme authority exists, presuppose the idea of a law which is valid not by positive sanctions, but by its own internal regard. It was therefore a necessary preparation for Grotius’ task to show the law to be given by nature (jus naturale) and valid apart from any positive legislation, and indeed such a one that is invented and introduced by man not for the sake of utility and selfishness, and which therefore can be bypassed for the sake of utility, but which rests on an ethical reason, which binds man par excellence. To refute that doctrine of utility and prudence such as represented in particular by Carneades in antiquity, and to establish an ethical principle of law, is the endeavor of the Prolegomena of Grotius’ work, with which the new era of legal philosophy mainly begins.
He constructs this law, in itself ethically binding, upon the convivial nature or the social instinct of man (socialis natura, appetitus socialis). Man has an instinct for community with others, indeed for a “peaceful and rationally ordered community.” Grotius did not conceive this urge to community as mere reciprocity of physical needs, but much more broadly, as good will towards others, especially in opposition to mere utility. It is to him the love of a condition in which common satisfaction is achieved for self and others. The gregarious nature in this sense now becomes the principle of law. What follows from it is the law of nature (jus naturae), is justice, while the opposite is unjust, illegal, and immutable (mutari non potest); it is for all times and for all peoples the supreme law. Thus did Grotius establish a principle for a system of natural law, a purely ethical one disregarding utility (jus non solius utilitas causa comparatum), and a purely rational one disregarding positive regulation. (It is not rationalistic because of its independence from positive law, but because of the source from which it is drawn, namely, human reason abstracted from God and the God-given world order, in which it, as shown above, goes so far as to claim a validity for the same even on the assumption that there is no God.)
Delimitation of the legal sphere
The sphere that stands under this principle and is to be regulated by it is, according to Grotius’ specific declaration, simply law in the actual or strict sense (ejus juris quod proprie tali nomine appellatur). He therefore firstly rules out law in the “broader” sense, which we call morality, namely the control of desires (fear and lust), as those that are regulated not by the drive to sociability, but by a different drive of human nature, namely, the judgment regarding the true lasting value or valuelessness of things, and secondly, as part of this broader law, the wise arrangement (prudens dispensatio) of the particular conditions of every man or every state, thus politics. Therefore there remains to the sphere of law (the sphere that stands under the principle of the drive to sociability) nothing but respect for mine and thine, namely property recognition, fulfillment of contracts, damages, and upon transgression, the punishment that pertains to this (alieni abstinentia – promissorum implendorum obligatio – damni culpa dati reparatio et poenae inter homines meritum). The deduction of these legal propositions is simple and obvious, they are undeniable conditions of peaceful coexistence, and it is exhausting in terms of that principle; because for the mere purpose of peaceful coexistence, nothing more is required.
Contract as the embodiment of natural law
In itself, only the sphere of private law is thereby derived from the principle of natural law. From this Grotius arrives at the state only indirectly, namely, through the medium of contract. It is a command of natural law that contracts must be kept, because (for the peaceful community) there must be some sort of mutual obligation among men and none other is conceivable (fingi potest) than contract. But then it must be assumed on the part of those who form a state (who have joined with a “Coetus”), that they have promised by express or implied contract, to obey either the majority or those to whom authority has been transferred. For this reason, even according to Grotius’ expression, obligation from agreement (obligatio ex consensu) is the “mother of all civil law.” It is based namely on the authority emanating from civil law. Indeed, even in the sphere of mine and thine he also derives the validity of several property from contractual introduction. So it is only contract that directly binds according to the law of nature, everything else is derived from it, and one might say that the entire essence of Grotius’ doctrine of natural law, without him being aware of it, is nothing else than merely the binding nature of contracts.
General ethical significance of the state, from which derives the public subject of authority and the public purpose
As Grotius proceeds from a general ethical basis for law, in the same way and in accordance with this basis he also attributes general ethical significance to the state. The state is the perfect union of free men, through which that law [Gesetz] of nature, a peaceful and orderly community, is to be realized. In accordance with this general ethical significance, the state, as differentiated from the person of the prince, as a human community, is the subject of public legal relations and public authority. There remains, therefore, the state itself, and its rights and obligations continue through all change of rulers, dynasties, and even forms of government – the immortality of the states (civitas immortalis), and the actions of the regent are binding on any successor, even those who are not his heirs, so that they are acts of state [Regentenhandlungen] (actus regii as opposed to privati). Similarly, the purpose of the state according to that general ethical significance is the common enjoyment (mutual recognition) of rights and the common utility. The public good is thus the supreme standard for decision (salus publica suprema lex esto), all individual rights must yield to it. From this in particular was derived the right of eminent domain (dominium supereminens).
Identification of nation and state
With this entire conception, the state is for Grotius entirely the same as the nation [Volk], the united people [Menschen], and therefore the public signifies to him only what is of common utility to all, not what is a higher necessity over all. Certainly he considers the people to be the state only insofar as it is imbued with a spirit, namely, just that entire civil life community (vitae civilis consociatio plena) the first product of which is the supreme authority. But the state never manifests itself to him as a unity or institute [Anstalt] to be distinguished from the people, which is also expressed in the fact that he everywhere uses the concepts civitas, communitas, coetus, populus as synonymous terms. In consequence, he grounds that identity of the state and perpetuity of its rights and obligations not on the unitary institute but rather on the fact that the rights and liabilities are the people’s, and mediates the binding nature of the acts of state on the successor not through the state but through the people, because of its being obligated by the actions of earlier rulers acting as its representatives, and tacitly transferring this obligation to the later rulers, which derive their power from it. In consequence of this, and this is the main point, for him the people is the subject of supreme authority (summa potestas). In free countries, it remains so completely, while in monarchical states it is not the exercise but the right (imperium in se retinet, quanquam non exercendum a corpore sed a capite). Therefore, here it is still the general subject of authority, while the prince, to whom it transfers that authority, becomes the special one (subjectum commune and proprium), similar to the whole body being the subject of sight even though first and foremost, only the eye is. Therefore the authority also reverts back (redit) to the people when the dynasty dies out, as having proceeded from it. –
From this implemented theoretical popular sovereignty, Grotius nevertheless does not arrive at any practical inferences against monarchy; on the contrary, he emphatically combats the then revolutionary doctrine of a supremacy and especially penal authority of peoples over their kings. This is because according to his doctrine, the king, although only gaining authority by transfer from the people, nevertheless thereby receives it truly and irrevocably; the people forever remain subjected to his own will and act. Grotius teaches a sovereignty of the people and a sovereignty of the king, but the former is only potential, and therefore can never do harm to the latter. But this conception, by which Grotius disposes of the natural consequences of his basic assumption, again is only possible through an inconsistency, a lack of awareness regarding his position, with which he is afflicted generally.
Private-legal character of the state contract
To wit: in contradiction to the general ethical and thus necessary significance that Grotius ascribes to the state, he conceives the contract founding the state in strictly private manner, as of arbitrary content, and since, as the state in general derives from contract, so necessarily do the specific form of government; all forms of government are declared legitimate by the backing of such a contract or similar title, such as, in particular, conquest, which according to Grotius’ position can be considered a (mandatory) contract. In this sense, he recognizes in particular the legality of a class of states which he already distinguished using private-legal characterizations such as patrimonial states or usufruct states, in which, namely, the ruler has full ownership of state authority, either because he has subjugated the people through war or contractually it has passed so completely into his hand that nothing is excluded. Certainly this term patrimonial state initially signifies only the irrevocable and unconditional competence of authority (including the power of disposal [Veräußerungsbefugniß]) and not absolutism. But according to other places, Grotius also allows the content, purpose, and scope of state power to depend on any contract whatsoever. Similarly to a man who of his own free will can give himself over to slavery, so also can the people give the sovereign power over itself in whatever way it wishes, because it is not utility but only will that is decisive according to the legal point of view, and therefore states are also justified in which the state power is intended solely for the benefit of the prince and not the people, thus entirely equal to the power over slaves, in accordance with the then prevailing Aristotelian characterization. There is obviously an inconsistency with regard to the concept of the general necessary essence of the state. If the legal basis for all relations only lies in the satisfaction of human desire for a peaceful and rationally ordered community, then a contract cannot be legally valid that allows the public authority to be used not for this purpose, but for the benefit of the ruler. This inconsistency had to be removed, which was done beginning with Grotius’ other suppositions up to the doctrine of Rousseau.
Now the same thing that holds for the state and the people within the state must also apply to the nations mutually. For these as well there exist standards by agreement (among which, undoubtedly, not only express but also tacit agreement is to be understood) which have as goal not the benefit of an individual state but the benefit of that great unity of states (magnae illius universitatis). Accordingly, war in particular is also based on fixed laws. There are only certain cases in which it can lawfully be conducted, mere advantage is no authorization, there are rules and restrictions according to which it must be conducted, and there are even temperaments of humanity by which not everything allowed by principles of law should actually be implemented.––
With this complex of ideas [Ideenkonception], Grotius opened a new path for various scientific fields. Even for ethics generally, he laid the foundation for scientific treatment by laying claim to an independent field separate from religion, and an independent knowledge separate from revelation; because if he also fell into error in this, by entirely separating God Himself from this purpose, yet he secured the problem of recognizing the moral commandments not as arbitrary divine commission, but in terms of their inner reason and essence. Still more decisively, he is the founder of “natural law” as an entirely new science which did not exist before him. Not only did he establish a new principle for the philosophy of law, the socializing nature in his sense, but he provided a new boundary for its subject matter. He first separated the actual sphere of law, which until then was mixed with others. He erected a natural law (jus naturae) as distinguished from morality and politics, while also distinguished from positive law. Legal principles shall exist which are not based on positive law and yet are not merely desirable principles worthy of pursuing, but which already are actually valid, legally binding principles that have nothing to do with the question of the appropriateness of the state constitution and state institutions, but are valid across all state constitutions and state institutions plain and simple, as unconditional legal standards. Such a science of general law, which is not morality, not politics, not the epitome of mere law-ideas, and not positive law, is precisely the specific nature of the discipline of “natural law” that Grotius founded and the entire construction of which, at least in its outlines, he already prefigured with a steady hand; and here again the mighty progress he achieved needs to be recognized, regardless of the untenability of his notions regarding such a law, which lay in distinguishing the law idea from the political idea. For the doctrine of state and state law, Grotius preeminently asserted the viewpoint of the public commonwealth as opposed to mere private entitlement to rule, as has already been pointed out in other places of this work. Above all others, however, Grotius accomplished a service for the law of nations, which was his intended task. Since it was no longer the church that maintained a joint order among the mighty of the earth, and no longer the emperor who was recognized as the supreme arbiter of their disputes, in international relations it was only the absolute will of the individual sovereigns which was valid, and there already had appeared the theory of mere utility which fomented the European condition of the thirst for unlimited aggrandizement on the part of courts. It was therefore a great thing to bring about, that not only utility but law is valid in the relations of nations, that even in war laws are not silenced, and that even what the law allows, humanity does not attempt. Grotius stands above all the subsequent practitioners of natural law until Kant, not only by being the first inventor, but also in the execution by richness of thought, and the perception and living conception of conditions, in consequence of which, which is also notable, falsehood does not emerge as determinately with him as it is veiled with others, even partially himself (as in particular the abscission from Christianity).
But as undeniable as these lasting merits of the Grotian doctrine are, he also, with this same doctrine, was also the first and already complete founder of that one-sided and therefore false orientation which in its consistency ends with the destruction of morality and justice. He sketched out the enterprise of implementing a legal construction by abstracting not only from the Author of the moral order but also from the content of the actually given (objective) moral order, simply from the nature of man. He gave the initial expression to the manner of presentation in which the state has no authority over men in itself, but only gets it through their contracting, and has no purpose in itself, but only for the purposes of (individual) men. This point of view is the decisive factor. The fact that Grotius personally and incidentally ascribes to the Christian revelation could not prevent the consequences thereof.
This also makes his relationship with Aristotle evident. The tradition in which the social nature of man contains the grounds of law and the state began with Aristotle and proceeded to Grotius; to that degree the sociabilist system has been regarded as nothing new, not the work of Grotius. But the same expression in Grotius has a completely different meaning in Aristotle. With the same expression, Aristotle means nature as the power in the universe which appoints people to social life, while Grotius means nature as the character or desire of men. According to Aristotle, nature in the state seeks the completion of that which it grounds in smaller circles, to which end man is by nature gregarious. According to Grotius, by contrast, man has a social need, which is why the state is an end of nature. Therefore Aristotle comes to an (objective) doctrine as to how the state by its very nature must be arranged, while Grotius comes to a (subjective) doctrine, how it must be designed to suit the nature of (individual) men.
Hence with Grotius a principle came to life which in its further development of necessity led to the doctrine of Kant and Rousseau, and finally to the French Revolution. The doctrine of Grotius that the duty of subjects has its basis in their tacit contract is in itself quite insignificant and innocuous. But it only needed to be developed in all its content and its consequences, and it became that which a century later overturned the order of Europe. So is a snowflake inconspicuous, which dissolves on the mountain peaks; but it rolls away and then falls as the crushing avalanche into the depths.
 Hugo Grotius, De Jure Belli et Pacis, 1625.
 This is the undoubted sense of §§. 8 and 10 of the Prologue. Many places indicate that Grotius understood law in the broader sense to be morality, preeminently Prolegomena §§. 41 and 44, where it reads: cum injustitia non aliam naturam habeat, quam alieni usurpationem, nec referat, ex avaritia illa, an ex libidine, an ex ira, an ex imprudente misericordia proveniat. Likewise lib. II, cap. 22. §. 16. Illud quoque sciendum est, si quis quid debet non ex justitia propria, sed ex virtute alia, puta liberalitate, gratia, misericordia, dilectione, id sicut in foro exigi non potest, ita nec armis deposci. In this sense, therefore, Grotius also judges the duty of parents to nourish their children, to be such a one that pertains not to law in the strict but in the broad sense (hence, morality): l. II, cap. 7. §. 4. This entire construction of the ethical sphere of Grotius’ can only be explained on the basis of then-extant scholastic teaching [Bildung]. That which there was divided subjectively into various virtues, Grotius established objectively as separation into spheres of life. The sphere of justitia commutative is what he construes as law in the strict sense; as law in the broad sense he allocates control of appetites, which according to Thomas was the object of other virtues but not justice, and the wise distribution of goods and positions according the inner worth and calling of persons, which according to Thomas was the object of justitia distributive. But when he transfers the separation to objective spheres of life, they automatically turn into a purification [Reinstellung] of the legal sphere over against morality and politics.
 Proleg. 15. 16. Cf. also lib. II, cap. 5, §. 17 and 23.
 Lib. II, cap. 2. §. 2. no. 5.
 “Est autem civitas coetus perfectus liberorum hominum, juris fruendi et communis utilitatis causa societas.” Lib. I, cap. 1, §. 14.
 Lib. II, cap. 9. §. 8. nos. 1––3 and §. 3.
 Lib. II, cap. 14. §. 1. nos. 1 and 2. §. 11. no. 2 §. 12. no. 2.
 Lib. II, cap. 14. §. 7.
 Lib. II, cap. 9. §. 3.
 “Non desinit debere pecuniam populus rege sibi imposito, quam liber debebat, est enim idem populus.” Lib. II, cap. 9 cit.
 “Nam imperium, quod in rege est ut in capite, in poulo mane tut in toto, cujus pars est caput: atque adeo regis familia extincta jus imperandi ad populum redit.” Lib. II, cap. 9 §. 8. lib. I, cap. 3. §. 7.
 Lib. I, cap. 3. §. 8.
 Lib. I, cap. 3. §. 11.
 Ibid. and lib. II, cap. 6. §. 3.
 Lib. I, cap. 3 §. 8, nos. 1, 2, 14.
 See Stahl, Philosophical Presuppositions (Vol. II, Book I of this work), §§. 24 and 28.
 See Stahl, Principles of Law (Vol. II, Book II of this work), §. 17.
 See Stahl, The Doctrine of State and Principles of State Law (Vol. II, Book IV of this work), §. 37.