Hugo Grotius (1583—1645)

GrotiusHugo Grotius was a Dutch humanist and jurist whose philosophy of natural law had a major impact on the development of seventeenth century political thought and on the moral theories of the Enlightenment. Valorized by contemporary international theorists as the father of international law, his work on sovereignty, international rights of commerce and the norms of just war continue to inform theories of the international legal order. His major work, De Jure Belli ac Pacis (The Rights of War and Peace), is particularly notable in this respect, as well as Mare Liberum, a doctrine in favor of the freedom of the seas, which is considered an antecedent, inspiration and the backbone of the modern law of the sea.

Grotius was heavily influenced by classical philosophy, most prominently Aristotle and the Stoics, as well as by the contemporary humanist tradition and the late-medieval Scholastics. Caught up in the religious strife of the Reformation, Grotius promoted an irenic vision that would unite and reconcile the Christian Church on the principles of civil religion and toleration. He was well known in his time as much for his poetry and philosophy of religion as for his work on law and politics but is best remembered for his influence on theories of the social contract, natural rights and the laws of war.

Table of Contents

  1. Life and Works
  2. Irenicism and Tolerance
    1. Religion and Civil Authority
    2. Relations with Non-Christians
    3. Christian Unity and Peace
  3. Sovereignty and Imperialism
    1. Divisible Sovereignty
    2. Resistance, War and Empire
  4. Natural Right and the Law of Nations
    1. Obligations from Nature and Custom
    2. Just War: Jus ad Bellum
    3. Just War: Jus in Bello
  5. Scholarly Interest in Grotius
  6. References and Further Reading
    1. Primary Sources
    2. Secondary Sources

1. Life and Works

Huig de Groot, best known by the Latinized name Hugo Grotius, began his life in the commercial town of Delft while, in 1583, the Dutch Republic persevered through a second decade of war for independence from Hapsburg rule and was already positioning itself for ascendancy as an overseas trading power. Born into a family with standing among the city elite and connections to the recently founded University of Leiden, young Hugo would find many opportunities to develop his considerable talents for scholarly pursuits even as a child. His family tutored him in Greek and Latin at an early age, introduced him to classical letters, and brought him up in the disciplines of Reformed faith. So outstanding were his gifts for intellectual work that he was welcomed to enroll at Leiden University at the mere age of eleven. At the university, the boy de Groot became a favored student of some of the most celebrated scholars of the time, discovering his talents in a whole range of subjects in the liberal arts and new sciences. His reputation as a promising young man of letters would open a number of doors for him in the political life of the time, where humanist expertise was a valued asset. The most auspicious of these opportunities came as he was preparing for life beyond the university. In 1598, no less a figure than Jan van Oldenbarnevelt, the Grand Pensionary and most influential personality in Dutch politics, invited Grotius to accompany his delegation to the French court. The embassy, which ultimately failed in its aim to renew the king’s military support against Spain, nonetheless brought Grotius into the fold of high politics and even staked him a reputation with the French court when Henry IV lauded the learned youth as “the miracle of Holland.” The connections he made in France enabled Grotius to extend his stay and earn a Doctor of Laws degree from the University of Orléans before returning to Holland the following year.

Entering into practice as a lawyer in The Hague, Grotius took advantage of chances to hone his rhetorical skills and found time to devote to his diverse scholarly interests. His earliest writings to go into print included several imitations of classical verse and translations of significant works in compass navigation and astronomy, the latter being of keen interest to his friends invested in the burgeoning overseas trade. In 1601, he published a tragedy, Adamus Exul (Adam in Exile), that earned him instant acclaim as a poet; it was a work that John Milton would later study in preparing his Paradise Lost. While Grotius prized these pursuits more highly than the mundane work of a lawyer, he always strove to please his patrons and clients. Indeed, his most lasting contributions to political thought took shape in the course of his professional duties during this period.

In 1604, Grotius was drawn into the sensational controversy over privateering in the Southeast Asian trade. The United Dutch East India Company had been rising quickly as a major player in European overseas commerce, and Grotius shared the view of many of his associates involved in the trade that the Company not only buoyed up the young republic with wealth but also weakened its adversaries by cutting into Iberian dominance of the East Indian routes. Still, acts of piracy by a private concern did not sit well in the public opinion of many citizens and allies. When asked by a friend with Company connections to write a brief justifying a recent and very lucrative seizure of Spanish cargo, Grotius went on to produce not only an ardent defense of the capture but an investigation into the deep principles of law that connected those separated by nation and culture. The resulting manuscript, provisionally titled De Indis (On the Indies), was never published in full until long after Grotius’ death (appearing in 1868 as Commentary on the Laws of Prize and Booty). It was the young jurist’s first systematic work on the problems of international affairs and was in many ways his most philosophically developed. Many of the arguments worked out in the manuscript—that there is a basic law of nature determined by the need to reconcile self-preservation with social life, that the authority to govern and even to punish derive from the rights of natural persons prior to the founding of civil societies, and that claims to jurisdiction over the open seas are invalid—would give direction to his later works.

In fact, the last of these arguments would appear in print in 1609 as the anonymous pamphlet, Mare Liberum (The Free Seas). The pamphlet, which Grotius pulled directly from the text of De Indis, once again served the interests of those in the Dutch political and commercial establishment that were insisting upon the right of access to overseas routes in the ongoing negotiations for a truce with the Spanish. The work argued not only that the Spanish claims to a trading monopoly in the Southeast Asia and elsewhere failed to square with the facts—that these were rights conferred by papal authority or acquired by just conquest—but that there was, in principle, no basis for any monopoly on access to the seas. The freedom of the seas was entailed by the very nature of private property. To privately own a thing requires that one can occupy it, taking it out of the common store, and that one can make full use of it. The sea cannot be contained and is too plentiful for its usefulness to be exhausted by a few; hence, no one can take exclusive ownership of the sea. The seas remain open to all. This question was of great importance in European relations during this period of intense competition between aspiring overseas empires, and Grotius’ work would frame the intense debate to follow. During this time in his early legal career, he penned a number of other manuscripts touching on matters of international relations that, while mostly unpublished, shaped his later work on the subject. The Parellelon Rerumpublicarum (composed 1601-2) explored the concept of ‘good faith’ in dealings with other nations through some flattering comparisons among the customs of the Greek, Roman and Dutch peoples. In his Commentary on Eleven Theses (circa 1602-08), Grotius worked out an understanding of the ruling power of a state—its sovereignty—and its relation to the principles of just war.

Having proved the usefulness of his talents to the ruling elite, Grotius’ star continued to rise. He gained recognition from Prince Maurits of Orange, the executive and military leader of the United Provinces, when in 1607, the prince appointed him as attorney general of the provinces of Holland, Zeeland and West Friesland. It was during this time that he became engaged to be married to a young woman from a distinguished family in Zeeland, Maria van Reigersberch. Her partnership and personal courage would carry the family through a tumultuous life that the young couple could not have expected at the time of their wedding in 1608. Soon thereafter, Maria gave birth to the first of seven children. As his focus shifted from legal practice to public service, Grotius began to put a number of his writings into press. His second celebrated tragedy, The Passion of Christ, came out in 1608, followed by the anonymous Mare Liberum in 1609 and a political history of the old Dutch republic, De Antiquitate Reipublicae Batavicae, in 1610. The historical account provided ideological leverage for the position that Holland had persisted in its republican form of government despite the princely claims of the Hapsburgs. The governing States of Holland commissioned Grotius to write a detailed history of the conflict with Spain, which he submitted in 1612. The States declined, likely due to the delicate truce, to publicize the work, leaving the Annales et Historiae de Rebus Belgicus to rest until his sons brought it out posthumously in 1657. Opportunity for higher office came again when, in 1612, the town council of Rotterdam offered Grotius the mayoral position of Pensionary. The title brought with it a seat in the States of Holland where he would collaborate more closely with his mentor, Oldenbarnevelt, and key players in provincial and national politics.

The political controversy that would end up defining Grotius’ tenure in office began with small rumblings when, in 1608, the professor of theology at the University of Leiden, Jacob Arminius, put forth a doctrine that challenged key features of the reigning Calvinist orthodoxy concerning predestination (see below: Irenicism and Tolerance). Calvinist church officials and divines came out strongly against the preaching of such a view. Though Arminius died the following year, the conflict escalated in a way that pitted the church establishment against the civil authorities over the question of who could rule on such doctrinal disputes. Grotius shared with many in the government of Holland some sympathies with the Arminian view but a desire above all to prevent such matters from disturbing the peace. He had been composing, during this time, a manuscript on the idea that all faiths shared a set of core doctrines, a viewpoint capable of promoting a certain equanimity towards squabbles over the finer points of theology. This was in any case the political attitude Grotius favored, and while he never published the Meletius manuscript, he developed several writings on the role of the state in managing conflicts over religion. The pamphlet, Ordinum Hollandiae et Westfrisiae pietas (1613), defended the ‘piety’ of the governments of Holland and Westfriesland in imposing a policy of toleration that allowed Arminians to preach their dissenting doctrine. Grotius himself had drafted the policy, which failed in its aim of mollifying the factions and, in fact, heightened the conflict between the civil and ecclesiastical authorities. Convinced that the practice of religion was a concern proper to civil magistrates, Grotius set about justifying his views in a longer treatise. De Imperio Summarum Potestatum circa Sacra argued that, to avoid a conflict of rights, there must be only one final authority within a state on how religion is to be practiced, that because of its mandate to keep civil peace and form responsible citizens this authority ought to come under the civil power, and that civil magistrates would do well to limit their judgments to the core doctrines Grotius had worked out in Meletius. He developed, though never published, the manuscript of De Imperio as the political conflict continued to escalate during 1614-17. His sympathies with the Arminian theology also grew during this period, and in 1617 he took it upon himself to brush back the charges of heresy with the publication of a theological work, Defensio Fidei Catholicae de Satisfactione Christi adversus Faustum Socinum.

As Grotius was being drawn further into the controversy, it came to consume national politics. The orthodox Calvinists, who were a majority at the national level and now had the backing of Prince Maurits, were demanding a national synod to settle the matter. This set up a standoff between Maurits, the national executive and commander of the armed forces, and Oldenbarnevelt, the most influential figure in the States assembly. Oldenbarnevelt led the elites of Holland, including Grotius, in blocking the synod and managing the dispute at the provincial level. That policy culminated in a decision, when riots broke out in 1617, to authorize local militias to suppress the disorder. Maurits denounced the act as an offense against his military authority, and he seized the opportunity to turn the tide against his political adversaries. At the end of an extended political and military campaign to push the Arminian supporters out of the establishment, he ordered the arrest of Oldenbarnevelt and his key supporters in August 1618. Grotius, with his mentor, was locked up and set for trial. A national synod, the famous Synod of Dort, was scheduled. Though incensed at the military coup d’etat against the sovereign institutions of Holland, Grotius calmly petitioned Maurits and the national States-General to no effect. The trials commenced the following year, and Grotius saw his mentor condemned to death for high treason. On May 18, 1619, his own sentence came down: confiscation of property and life imprisonment.

Although he would strive for the rest of his life to vindicate himself and lift the disgrace of the charges from himself and his family, Grotius entered at the age of thirty-six into his term of imprisonment in the castle Loevestein. The only solace of his confinement was that his family was allowed to reside with him and that on her regular leaves his wife Maria was able to bring back books and papers. The scholar was able to turn his isolation to some greater purpose. In Loevestein, Grotius renewed a number of neglected projects. He wrote, fully in didactic verse, a more systematic treatment of his view that there are essential elements common to all religions and that the doctrines of Christianity were recognizable through reason as the most consistent and highest expression of the common faith. The work, initially composed in Dutch, would serve as the basis for his renowned De Veritate Religionis Christiane (The Truth of the Christian Religion). Through his work in law and legal history, he had conceived the plan of writing a rigorous guidebook on jurisprudence of Holland in the vernacular of the Dutch language. The later publication, in 1631, of Inleidinge to the Hollandsche Rechts-geleerdheid (Introduction the Jurisprudence of Holland) would eventually give his book a status in Dutch law analogous to Blackstone’s Commentaries in the English system. Grotius was convinced that he could achieve the same kind of ordered treatment of the concepts, principles and precedents governing relations at the international level. Closed within the walls of his cell, he reached out for a global view of human affairs and prepared parts of what would become the massive treatise, De Jure Belli ac Pacis (The Rights of War and Peace). At the same time, Grotius was looking beyond the walls of Loevestein with a mind for a more immediate scheme: escape. He knew that he had support in the court of Louis XIII in France, and his hopes for reestablishing himself pointed towards Paris. Maria and the family’s young maid-servant, Elsje van Houwening, hatched the plan for escape. On March 22, 1621, Maria made arrangements for a chest of books to be shipped to the nearby town of Gorcum, then helped her husband into the cramped chest and watched Elsje accompany the guards as they unwittingly delivered their prisoner into the hands of friends. A month later, Grotius was in Paris, separated from his family, exiled from his beloved country, yet free.

The long period Grotius spent in exile saw the publication of his most remembered works. Having secured the support of Louis XIII and being reunited with his family, he prepared several manuscripts that he hoped would restore him to prominence. The Apologeticus, appearing in 1622, was straight to the purpose: it contained a full defense of his conduct as a public official of Holland. Despite his earnest pleas of loyalty and the best efforts of his friends, the States-General spurned his arguments and authorized a bounty on him. He turned his attention to the scholarly projects begun in Loevestein. The treatise on the universal law of nature and nations, divided into three hefty books, grew out of the reflections on the subject he had begun twenty years prior. Its first book developed an account of natural justice, so central to his earlier arguments about the Southeast Asian trade, and laid out a broad framework for judging “controversies of any and every kind, as are likely to arise” (JBP I.I.i)—those among politically sovereign entities, private parties, or rival camps within a state. The lengthy second book provided a grounding for the rights in one’s person, property, and sovereignty (subjects he was revisiting from Mare Liberum and his unpublished commentaries) and a detailed consideration of the ways such rights could be acquired, transferred, lost, and protected by recourse to war. The third book, dramatizing the gap between the prevailing customs of warfare and the demands placed on us by a more humane conscience, considers what responsibilities parties have to all those they impact in wartime and in upholding good faith in efforts to build the peace. Many of the arguments of the work were forged in Grotius’ career as an advocate and public official, though he insists in the Prolegomena to the treatise that his perspective in the work is that of a mathematician, abstracting away from particular facts and controversies of the day. When the first edition of De Jure Belli ac Pacis made its appearance in 1625, its readers would have no shortage of conflicts to which to apply its ideas about war and peace, from the campaigns of conquest and appropriation overseas to the long-raging religious conflicts on the continent that were escalating into what would be the Thirty Years War.

Grotius continued, while in France, to write and visit scholars. His Latin edition of The Truth of Christian Religion came out in 1627. It would become his most widely read and translated work. Despite the unreliability of his pension from King Louis, he turned down some tempting offers to serve as a diplomat for other nations and instead renewed his efforts to rehabilitate his standing in the Netherlands. Upon the death of Prince Maurits, Grotius returned to Holland in 1631 in hopes of finding favor with the new Prince of Orange, Frederick Henry, but an arrest warrant from the States-General forced him to flee and take up refuge in Hamburg. Grotius and his wife remained for more than two years in the city without any great prospects. He set himself to composing a third major tragedy, Sophompaneas (Joseph), which would appear in 1635. By that time, his work on the laws of war had brought opportunity to his doorstep. In 1634, he was called to meet with the Swedish High Chancellor, Oxenstierna, who informed him that the recently slain King Gustavus Adolphus had been a great admirer of De Jure Belli and expressed a desire to bring Grotius into the service of Sweden. A major power, Sweden had risen up as a champion of the Protestant cause in the bloody war that gripped Europe, and Grotius was asked to provide counsel to the young queen and serve as her ambassador to another key power, France. The position required that he renounce his Dutch citizenship in order to declare his loyalty to the Swedish crown. Though he never let go of the hope of returning to his home, he accepted. The de Groot family would once again take up residence in Paris.

As ambassador, Grotius was charged with negotiating the terms of French support for the Protestant alliance. The relations were especially fraught due to the delicate position that the French crown, under the guidance of Cardinal Richelieu, had carved out between its opposition to Hapsburg power and its defense of Catholicism. As France increasingly entered the battle fray, much of Grotius’ duty was directed to the war effort. His scholarly projects from the late 1630s-40s, however, took as their object a long-cherished goal: the reconciliation and peace of the Christian community. He began in 1638 on a scriptural commentary that would deflate Protestant rhetoric charging that the Pope was the Antichrist. That same year he slipped an anonymous treatise through an Amsterdam press defending the lay administration of the Eucharist. He then released two lengthy collections of annotations, one on the New Testament and one on the Old, which emphasized the ethical role of the scriptures over the more divisive questions of theology. Building on the idea of shared core doctrines he had explored in his earlier manuscripts, he frankly promoted his vision for a reconciled faith in an appeal printed in Paris in 1642, Via ad Pacem Ecclesiasticam (The Way to Church Peace). Grotius had great hopes that the time was ripe for this vision, but he was disappointed when his arguments were swallowed up in the same old sectarian vitriol.

Having passed the age of sixty, Grotius met with some relief his recall to Swedish court in 1645. The Queen offered to settle his family in Sweden, but he instead requested a passport so that he could rejoin Maria and pursue opportunities elsewhere. He embarked in August in the midst of a terrible storm that damaged the ship and washed it upon the German coast. The ordeal left him ill and weather-beaten. With the aid of servants, he made it to the town of Rostock where he found a hospice. His condition worsened, and death came on August 28, 1645. Arrangements were made to convey his remains to Delft, where the town of his birth bestowed him with the honor that he could not regain in life by interring his body in the Nieuwe Kerk alongside the most celebrated figures of the republic. Maria resettled in Holland, and their sons set about preparing, from Grotius’ papers, updated editions and previously unpublished manuscripts for the press. De Jure Belli ac Pacis, especially, would come to have enduring influence as the Enlightenment philosophers of the next generations embraced its framework of natural jurisprudence as a model for a modern science of law and morals. His work would become a point of departure for those natural lawyers focusing on the law among nations, from Pufendorf and Barbeyrac to Thomasius and Vattel. It would inspire radical ideas about natural rights and the social contract in the Anglo-American political discourses of Hobbes, Locke, Jefferson and Madison. For the Scottish Enlightenment, it would be required reading, informing the moral theories of Carmichael, Hutcheson, Hume and Smith. As natural jurisprudence gave way to positivism and idealism in 19th-century European thought, the place of Grotius receded in moral and political theory, but his work would be recovered in the context of emerging ideas about the international legal order as the next century approached. His work is most widely known today among those working on international relations and law, though there has been rapidly expanding scholarship on his contributions to political thought, ethics, and the philosophy of religion.

2. Irenicism and Tolerance

In the politics of the Dutch Republic and with regard to the broader religious strife in Europe, Grotius fashioned himself as an irenicist, one who seeks to bring the different denominations of Christianity together. The inflammatory conflicts among the Christian churches, which remained a persistent cause of war and upheaval in the political life of European societies, was in Grotius’ view largely attributable to excesses of dogmatism (see Heering 2004). If dogmatic claims could be reduced to an agreeable set of core tenets, he reasoned, then the various sects would have grounds for cooperating towards a reunified Christian church while allowing more esoteric matters to be contested without posing a threat to peace. This hope for Christian peace and unity characterizes Grotius’ theologically-oriented works from his early Meletius (1611) to Via ad Pacem Ecclesiasticam (1642), among his latest writings at the height of the Thirty Years War.

a. Religion and Civil Authority

In the early decades of the 17th century when Grotius’ was cutting his teeth in Dutch politics, the temperature was rising on a theological dispute concerning salvation and freedom of the will. The reformed churches, which had the backing of the civil authorities, were founded on orthodox Calvinist doctrine. The standard Calvinist view of salvation held that God’s choice of who would be saved preceded the act of creation; this grace was, consequently, not a status that could be earned through good works but rather was predestined. This view was consistent with the dominant Protestant interpretations of scripture and represented a social and ethical worldview that was compelling to the reformed faithful. Yet this view also carried the ethically troubling implication that individual choice makes no difference to how one stands with God and, as the Leiden professor of theology, Jacob Arminius, would argue, did not account for elements of scripture that seemed to acknowledge a role for human will. Arminius maintained that God’s saving grace was on offer to anyone while still accepting the basic Calvinist premise that, prior to any human act, God had already determined who He would actually elect to everlasting happiness. The paradox could be resolved by recognizing that God’s grace might be resisted. This elegant solution enabled Arminius to account for freedom of the human will while retaining the key Protestant tenet that grace alone, not works, qualifies the elect. The Arminian view of salvation, to draw on Richard Tuck’s illuminating analogy, understands God’s offer of grace to the elect to be much like a parent’s offer to buy something for a child: “the child can refuse the offer, but he cannot purchase the present himself” (Tuck 1993 p. 182). While representing a significant revision to orthodox Calvinism, this view remained consistent with the larger doctrine.

The political question, however, was whether adherents of the Arminian position should be allowed to teach it within the publically established churches. Grotius’ writings from this period confront both the theological and political aspects of the debate. On the question of theology his sympathies laid with Arminius, and his defenses of the view led up to the publication of the substantial De Satisfactione (published in 1617), which distinguished many of the Arminian tenets from the ‘Socianian’ heresies charged by the view’s opponents. Politically, the Arminian preachers were seeking a policy of toleration within the public churches. Grotius and others aligned with Oldenbarnevelt recognized the advantages of such a policy for preserving quiet in the republic. Characteristically, Grotius saw the policy as rooted in philosophical concerns. As early as the (unpublished) manuscript Meletius (1611), he was developing a philosophy of religion according to which all faiths shared core beliefs about the nature of divinity and its role in human life. While this view stressed commonality, it did not entail pluralism. A religious tradition may possess a stronger claim to truth than others in virtue of its consistency with the central doctrines and the credibility of its supporting testimony; for Grotius, Christianity held this title. (This defense of Christianity is most fully developed in Grotius’ most widely published and popular work, On the Truth of the Christian Religion.) Yet Christian tradition, too, had a further set of core doctrines which were necessary for proper worship and for the promotion of responsible citizenship. The church could accommodate friendly debate over finer matters of theology as long as it was firmly rooted in the necessary articles of faith. This philosophical framework, while not made fully public at the time, undergirded Grotius’ advocacy of the toleration policy, which the States of Holland would eventually adopt.

The policy, Grotius well understood, required not only justification but also legitimacy: in defining acceptable doctrines, the civil authority was asserting itself in sacred matters. Grotius addressed this issue in his 1613 pamphlet defending the toleration policy, Ordinum Hollandiae et Westfrisiae pietas, and went on to develop the argument for the central principles into a major essay on the authority of civil government over the public practice of religion. De Imperio Summarum Potestatum circa sacra (1614-17, unpublished) argued that the supreme civil power holds legitimate authority over all matters concerning the public interest, whether sacred or profane. In addition to finding support from scripture and tradition, Grotius grounds his case on the simple Aristotelian argument that, because the commands of multiple authorities would allow for conflicting obligations, there can be only one supreme authority in a jurisdiction (ch. 1). Holding this authority enables the supreme power, then, to preserve civil peace as well as to promote, through the effects of religion, the formation of obedient and upright citizens. The bulk of the work is thus occupied with defending the plausibility of this conclusion by clearing away misconceptions and by reconciling it both with the variety of forms of political and legal organization and with the special calling of the church. To accept the authority of the civil power in religious matters, Grotius argues, does not imply that magistrates are competent to determine the truth of all fine points of theology: a wise ruler will make use of counsel from the most reliable pastors. With even greater wisdom, a ruler would do well to abstain from pronouncing on all but the most essential articles of faith, those that are necessary for salvation (ch. 6, 9). As an instance of an inessential matter in which a “prudent silence” recommends itself, he offers those “questions about the order of predestination and the reconciliation of human free will with grace” (ibid). The policy of the States of Holland, in this framework, was a form of containment: the policy defined the boundaries of permissible doctrine at the point that would endanger the salvation of those who accept it, while allowing the disagreements inside these bounds to play themselves out. Such was Grotius’ recommendation, in both theory and practice. At bottom, however, the policy had its validity not in view of its laudable tolerance but on Erastian grounds. (The citations in the work acknowledge the influence of Thomas Erastus, who a generation earlier had argued for the supreme authority of the state in church governance.) The central position of De imperio was that any policy issued by the civil power would be valid so long as it did not contradict God’s will. That this Erastian position made room for toleration and contributed to civil peace only added to its appeal.

b. Relations with Non-Christians

The principle of toleration guided Grotius’ handling of the Arminian conflict and also served as an ideal in his view of dealings with non-Christians. Among the groups that had found haven in the Netherlands from the Inquisition were Portuguese Jews, and Grotius was asked during his time as a public official to reconsider what ought to be the policy the States towards the presence and worship practices of Jewish communities. His Remonstrantie on the question was of a piece with his developing philosophy of public religion: Jewish worship could be consistent with the state interest in religion, as Judaism accepted the fundamental doctrines regarding God’s existence and concern for human conduct. The policy recommendation was to afford civil liberties and freedom of worship to Jews, under certain restrictions that would serve to “safeguard” the salvation of Christians. This meant, for instance, that Jewish synagogues would not enjoy the same freedom to preach to Christian audiences that could be granted to Arminian and Calvinist disputants, but Grotius maintained that this encumbered status was preferable to the other options in the field. He opposed forcing Jews to practice Christianity on the grounds that such a policy was incoherent, since faith cannot be forced, as well as sinful, since it would induce people to false professions. An alternative was to forbid Jewish worship altogether, but this would promote godlessness, which would be intolerable. Finally, to those who were calling for expulsion, Grotius gave a sustained response partly grounded in principles of natural law: the social bond that nature establishes among humans should not be severed except as punishment for crime. Jewish practice did not transgress natural law, and its faith supported civic life. It was proper, therefore, that Christians and Jews share social arrangements on the basis of common principles of public order and justice.

The same balance between Christian privilege and the potential for peaceful cooperation underwrote Grotius’ approach towards the expanding relationships between Europeans and non-Christian societies around the world. The principles of natural justice in De Jure Belli ac pacis—which grounded claims to sovereignty, property, and the fulfillment of pacts—were valid and binding in any human encounter, requiring no special relation to God. The principles would oblige us, in Grotius’ famous phrase, “even if we should concede (etiamsi daremus) that which cannot be conceded without the utmost wickedness, that there is no God, or that the affairs of men are of no concern to Him” (JBP Prol. 11). Mutual recognition of natural law provided the basis for any two parties to arrive at just and peaceful terms of association, most notably those concerning trade and alliances. This did not imply that all practices regarding religion were consistent with natural law. Because a sense of justice is not sufficient to motivate humans routinely to do right, the broader human society, even more than civil societies, depends upon religion to maintain order and instill reverence for its norms (see JBP Prol. 20 and II.XX.XLIV.6). To reject God involves not only the “utmost wickedness” but a criminal disregard for human society. Indeed, the two tenets that Grotius identifies—that there is a God and that human affairs are of concern to Him—constitute what he takes to be the core of religious belief, found in all societies. Those who oppose these core beliefs may be punished, by war if necessary, but differences among the religious are not, in themselves, grounds for war (JBP II.XX.XLVI-XLVIII). Pagans, polytheists, Jews and Muslims might fail to accept the “truths” of Christianity, but their participation in the common faith supports the basic ethical structure of society. Christianity, even under non-Christian sovereigns, yet has this privilege: that in virtue of its claim to truth, its adherents must not be punished for teaching the Gospel (JBP II.XX.XLIX). The right to suppress religious doctrine, which De imperio claimed for the civil power, extends only to teachings not essential to Christian salvation.

c. Christian Unity and Peace

The privileged status of Christianity among the world’s religions is the subject of The Truth of the Christian Religion. As in De Jure Belli, composed around the same time, Grotius argues that a basic understanding of divinity and its role in the world is accessible through the use of the natural capacity of reason alone. Such truths include not only the existence and providence of God, but also God’s oneness, perfection, causal responsibility for all that happens, and judgment in the afterlife. The proofs Grotius offers are not original but are borrowed from sources both ancient and recent, owning that people of varying sophistication have long been able to reason back to a necessary and singular ‘first cause’ and to grasp that the perfect nature of such a cause would not neglect the good of all creation (ch. 1).  While some of these points require more subtle thought than others, all people can in principle arrive at the conclusions through rational reflection. Christ, however, is known through history. To learn of redemption and of what is required for salvation, one needs access to particular facts about Christ’s coming and His call to the faithful. The relevant facts, still, are supported by reasonable inferences based on reliable testimony (the evangelists), the consensus of historians, and the evidence of miracles performed. This project of deriving religious knowledge through rational investigation is what later philosophers would call “natural religion.” Significantly, Grotius argues that these facts gain further confirmation when one recognizes that the doctrines of Christianity have the greatest intrinsic appeal. The Gospel has this appeal in virtue of the reward it promises (the eternal beatitude of the soul), the quality of its ethical teachings (obeying out of love rather than fear, showing love to neighbors and enemies, and so forth), and the impeccable character of its teacher, Christ (ch. 2). Experience and rational consideration, while sufficient to establish the truth of Christianity, may not convince as readily as inferences from mere reason. Indeed, immediate acceptance is not possible without God’s help. On these grounds, Grotius would argue in De Jure Belli that one may neither punish those who fail to embrace Christianity nor impose belief by force (II.XX.XLVIII). Christians would do better to impress non-believers with their ethical example and offer persuasive arguments for conversion.

To this end, De Veritate provides a detailed debunking of other faiths. While its arguments reveal that Grotius undertook a serious study of non-Christian religions—with the aid of friends such as the Hebrew and Arabic scholar, Thomas Erpenius—some of his characterizations are far from generous, repeating old slurs about Jewish animosity towards Christians and the violent character of Islam. The arguments of the book were, after all, calculated to more than one purpose. Grotius intended the book to be of special use to seamen, whom while off to many corners of the earth to establish Dutch trading interests, would encounter a dazzling diversity of religious belief that might not only elude their attempts at persuasion but also challenge their own faith. It was the Christian reader, most of all, who may need to be assured of the Gospel’s special claim to truth.

The further effect Grotius hoped De Veritate would have on its Christian readers was to impress upon them that, in the range of religious diversity, the similarities among Christians are much more significant than the differences. The irenicist program that Grotius pursued in his later years had two main prongs. The first provided a map for Christian reunification based upon minimal agreement regarding core doctrines, beyond which some difference of belief and practice could be accommodated. The second urged Christians to recognize that the most important lessons to be taken from scripture are its ethical teachings, not its dogmas. This was the simple, practical faith that he saw reflected in the earliest Christian community and in the Christian humanists, like Erasmus, whom he so much admired. It was also a faith of which civil authorities, responsible for civic peace and virtue, could be worthy custodians.

3. Sovereignty and Imperialism

Connecting the political and international thought of Grotius is his conception of sovereignty, the supreme right of governing (summum imperium). The mark of the sovereign power is that it “cannot be made void by any other human will” (JBP, I.III.viii). Within a state, it is the highest authority; internationally it encounters other sovereign powers, among whom none holds a superior right.

a. Divisible Sovereignty

The guiding idea in Grotius’ treatment of sovereignty, as with his treatment of rights generally, is that systems of rights are radically alterable through the ways people choose to dispose of those rights. As a result, societies will vary widely in how they organize the powers of sovereignty. Philosophers might argue for the advantages of one scheme or another, “but as there are several ways of living, some better than others, and every one may choose which he pleases of all those sorts; so a people may choose what form of government they please: neither is the right which the sovereign has over his subjects to be measured by this or that form, of which divers men have divers opinions, but by the extent of the will of those who conferred it upon him” (JBP I.III.viii). What justifies a scheme of rights is that it has arisen from the historical choices of their legitimate holders, not any features of its form. This principle gave Grotius a great deal of flexibility in defending different political arrangements, provided the facts of history for the given society would play along.

On one side, Grotius was able to argue against royalists who sought to define sovereignty as an indivisible package of prerogatives that could be vested in only a singular will. Grotius takes this claim, which Jean Bodin had advanced a generation earlier, at face value but treats indivisibility as a purely conceptual point: to institute civil power in a society consists in gathering up a certain package of governmental rights and in designating who will hold that power supremely. The rights of governing come as a package, but a society may, if it chooses, designate different holders for the various rights.

Grotius developed this position early in his career in an unpublished manuscript that he called Commentary in Eleven Theses. The practical divisibility of sovereignty is an indispensable premise for the political argument of the work, which defends the ongoing Dutch war against the rule of the king of Spain. Unlike earlier apologists, Grotius does not conceive of the war as a revolt based on right of a people to resist a tyrannical ruler but rather as a war between sovereign powers (see Borschberg 1994 pp. 169ff. and Keene 2002 pp. 45ff.). If one studies the history of rights in the Dutch case, Grotius argues, one finds that the Dutch people did not transfer all governing rights to a prince bur reserved some, in particular the right to levy taxes, to the States of Holland. While holding supreme power on many matters, the Spanish king had sought to usurp a further supreme power from the States, an act which provided them a just cause to wage war in defense of its right. Put in the language of sovereignty, the king possessed no right to render void the will of the States when it came to taxation, just as this particular right of the States could not render void the king’s rights in other matters: each was supreme within the scope of its own authority (cf. JBP I.IV.xiii). Grotius retained and systematized this conception of divisible sovereignty in De Jure Belli, where he also considered the criticism that such arrangements based on divided powers were recipes for civil strife. His answer insists on the principle with which he began: while one can point to inconveniences in any arrangements, the only relevant question in matters of right is whether those arrangements were the ones chosen (I.III.xvii).

On the other side of the political spectrum, Grotius argued against theories of popular sovereignty. The position of constitutionalist thinkers, such as those among the reforming Huguenots who would come to be called ‘monarchomachs,’ was that the right of kings to rule derives from the rights of the people; since some of these rights are inalienable, the representatives of the people retain a right to resist a regime that tyrannically usurps these rights. Grotius’ response was to grant that rights originate from the people but to argue that the people can choose to alienate whatever rights they wish, even up to the extreme of enslaving themselves to another (JBP, I.III.viii). Utter subjection to an absolute monarch is, therefore, entirely possible and consistent with the history of political arrangements in many societies. Grotius’ flexible approach enabled him to defend the republican principles alive in the Dutch provinces from one side of his mouth while shoring up the absolutist claims of his later patrons from the other. In his defense of the latter claims, we find Grotius even paying homage to the time-worn doctrine of Aristotle that some people are naturally suited to be slaves. Importantly, Grotius does not admit the doctrine as grounds for imposing slavery but rather repurposes it: the doctrine can explain why a people might choose of their own accord to hand over their full rights to the more prudent government of another. Ineptitude at self-rule, it turns out, is just one of many considerations that might factor into the selection of a form of government.

b. Resistance, War and Empire

Grotius’ understanding of sovereignty carries several implications for his theory of just war. The first concerns his position on the “right of resistance,” the hotly contested question of whether a subject people may ever justly depose a ruler for misgovernment. While Grotius rejects constitutionalist arguments that reserve inalienable rights to the people, he finds a way to preserve this rationale for resistance in a more limited form. It is unlikely that most civil societies would have been founded on utter subjection. In the absence of clear evidence that subjects have completely alienated their rights, one has to presume that rational people would have preserved their most basic rights against arbitrary treatment. This presumption attaches only in cases of “extreme necessity,” as when a government turns its sword on innocent subjects, and then only when resistance could be carried out without creating an even bloodier civil conflict (I.VI.vii). When Grotius invokes this argument from extreme necessity, he relies on what Richard Tuck has called a kind of interpretive charity (1979 pp. 79-80): since civil authority is a human institution, the bounds of which are derived from the wills of those who established it, one must credit the founders with intentions that would rationally advance, not undermine, the aims of civil association. (Compare the parallel reasoning in limiting the rights of property, Second, Grotius assigns a role in this context to third-party humanitarian intervention. Even if it should turn out that subjects must bear the most arbitrary assaults from their proper sovereign, a third-party would remain free from the special obligations that constrain subjects from resisting and could intervene on their behalf. Such interventions should only be attempted when it is evident that a government is committing gross injustices against its people—“such Tyrannies over subjects, as no good Man living can approve” (JBP II.XXV.viii). The third implication concerns Grotius’ complicated relation to imperialism. In defending the legitimacy of diverse forms of political authority, he is rejecting the principle behind those forms of imperialism that seek to impose a more enlightened form of rule for the good of the governed. Elsewhere in De Jure Belli he explicitly refutes the argument that slavery can be imposed on those who might be naturally suited to it (II.XXII.xii) and castigates those who claim rights of ‘discovery’ over lands already occupied by supposedly less enlightened folk (II.XXII.ix). On these points, he is in agreement with earlier critics of the Spanish conquests such as Francisco de Vitoria and Bartolome de las Casas.

The strategies of commercial imperialism, which characterized Dutch practice, found much more support in Grotius’ theory of just war (see generally, Tuck 1999 ch. 3, van Ittersum 2006, Wilson 2008, Thomson 2009). The whole concern of De Jure Belli is how to justly settle controversies in the dealings of those who do not live under a shared system of civil laws. In the context of global trade, such dealings will involve the claims of private parties as well as the contentions of kings and states. It ultimately falls to each party, when operating outside the jurisdiction of a common court, to judge the controversy based on the applicable standards of natural, customary, state and divine law. Significantly, Grotius maintains that such relations can be peaceful so long as those involved have a clear understanding of the law and hold themselves to norms of justice, equity, temperance, and humanity. Yet, just as magistrates duly back their rulings with force, those involved in a dispute have the right to redress injuries by means of war. Used rightly, De Jure Belli would provide all parties with a clear understanding of how the law applied to various disputes and educate them in how to render fair and responsible verdicts. However, used rightly, it would also give trading powers the flexibility to leverage their arrangements with non-Europeans and the justifications to uphold these arrangements with force. One stratagem it enabled was encroachment on local sovereignty (see Keene 2002 pp. 48ff and 79ff). Grotius’ position was firmly that non-Christian rulers could hold full title to sovereignty, but his view of sovereignty was that its marks could be divided up among various holders. A foreign trading power might enter into an alliance with a ruler that required him, for instance, to provide land for a trading ‘factory’ or deliver up his people’s labor. These arrangements do not, in themselves, transfer any mark of sovereignty, but Grotius argues that, if the foreign power (unjustly) usurps this right over time without being challenged, its “long possession” provides it with a claim to sovereignty that is now just (JBP I.III.XXI.10-11). Because marks of sovereignty can be divided off in this way, the foreign power can take over limited rights of its own without being guilty of usurping the broader authority of the king. Once the limited right was established, however, it could also be protected with force should the king try to reconsolidate his power (by the same right that the Dutch defended their limited sovereignty against the ambitions of their Spanish overlord). Had the rulers of Southeast Asia read Grotius’ work, they might have found a useful warning about the risks of getting entangled with a powerful ally; the readers among the European mercantile class would also see its usefulness.

The natural-right framework of De Jure Belli also empowers parties to a contract to arrive at their own judgments about how to interpret indeterminate clauses (JBP II.XVI) and authorizes any party, public or private, to execute punishment for culpable violations of the law (II.XX). The idea that war-making can be understood as an extension of the right to punish had been part of the Christian just-war tradition from Augustine through Vitoria and Suarez, but Grotius reconceives punishment as a natural right that obtains prior to civil authority (see Tuck 1999 pp. 102f. and Straumann 2006). In circumstances beyond civil jurisdiction, law-respecting persons can take it upon themselves to police and punish crimes affecting society. Because this exercise of power over another assumes a position of superiority, Grotius recognizes the need to explain how this difference in standing can arise among those who are equal by nature. His solution is to point out that violators demote themselves beneath the rest of humanity (JBP II.XX.iii). Anyone who remains in this position of moral superiority can properly execute punishment. The natural right to punish was an important innovation in Grotius’ early De Indis, where he argued that Dutch merchants had legitimate authority to punish the Portuguese for monopolizing the seas (fol. 40). It remains a key feature of his theory of punishment in De Jure Belli, where it provides a further source for just causes to resort to war. In contrast to the anti-imperialist arguments of Vitoria and the school of Salamanca, which had maintained that the princes of Europe had no authority to punish those beyond their jurisdiction except in response to ‘an injury received’ (On the Law of War q.1 a.3; see also On the American Indians q. 2 a.5), Grotius opens the door to punitive war against those who commit ‘crimes against nature.’ Elevated as moral superiors above regimes that enjoin or condone manifestly unjust practices—including cannibalism, piracy, the oppression of their own people or the cruel treatment of foreigners—outside powers may seek to punish these regimes in the interests of human society (II.XX.XL). Adopted while Grotius still had ties to the interests of the Dutch trading companies, this interventionist stance would have expanded the range of justifications available for colonizing lands in both Asia and the Americas (see Tuck 1999 pp. 103-4 and van Ittersum 2010).

At the same time, Grotius shows an awareness, and some discomfort, that his position could be used as a pretext for expansionist wars. He cautions that only violations of universal norms, not of the evolving customs of Europe, count as punishable offenses. Quoting Plutarch, he explicitly warns of the lurking temptations of imperialism: “To wish to impose civilization upon uncivilized peoples is a pretext which may serve to conceal greed for what is another’s” (II.XX.XLI). The structure of Grotius’ position, characteristic of the framework of De Jure Belli, both insists on strict adherence to norms of justice, equity and humanity while still affording the powerful the flexibility to interpret, judge and enforce those norms by their own lights.

4. Natural Right and the Law of Nations

The broadest principles of just war in De Jure Belli ac pacis derive from two sources: the norms of natural justice and the customary law of nations (ius gentium). (Other human and divine laws, importantly, also lay down binding principles for those who have received them, but these sources do not have the universal character of the laws of nature and nations.) On any given question regarding the resort to war or its conduct, both systems of law must be consulted, as each system is capable of influencing the rights and obligations of the other.

a. Obligations from Nature and Custom

The account of natural law in De Jure Belli, heavily influenced by the Stoic notions of Cicero, begins from two universal human concerns: self-preservation and social connection (see JBP I.II.I and Prol. 6-8). The rights of obligations of natural law are all justified in terms of the rational balancing of these two primary concerns. This approach is an outgrowth of Grotius’ earliest work on the laws of war, De Indis, where he argued that the imperative of self-preservation justified two permissions of natural law: to defend one’s life and to acquire possessions (fol. 5’-6). The need for human fellowship justifies two basic obligations towards others: to refrain from inflicting injury and from seizing their possessions (fol. 6’-7’). One apparent change that Grotius makes to his earlier theory regards the basis for these obligations. In De Indis, he aligns himself with a voluntarist account of obligation, found in medieval thinkers such as Ockham, which maintains that natural law is binding upon humans in virtue of the divine will that commands it (fol 5’). The design of nature is one way in which we receive God’s commands. By the time of De Jure Belli, Grotius seems to accept the alternative, intellectualist position that natural law binds us by teaching what both humans and God can recognize as necessary for human life: it shows us not what is obligatory because commanded but what is obligatory or permissible “in itself” (JBP I.I.x). In fact, there is much ambiguity in the later work as to which position Grotius accepts, showing itself even in his very definition of natural law as “a dictate of right reason, which points out that an act has in it a quality of moral baseness of moral necessity; and that, in consequence, such an act is either forbidden or enjoined by the author of nature, God” (JBP I.I.x). This definition is perhaps closest to the ‘mediating’ position more recently advanced by Suárez, maintaining that intellect could recognize what is, in itself, good or bad for humans but that only God’s command makes it obligatory to live accordingly (De Legibus II.VI; see Schneewind 1998 pp. 61 and 74).

What is clear is that Grotius draws a basic distinction in law, following Aristotle, between obligations derived from nature and those derived from an authoritative will (JBP I.I.ix and xiii-xvi). Sources of this second, ‘volitional’ type of law can be divine (as revealed in scripture) or human, and the latter includes not only the laws of particular states but also those laws that nations accept in their relations with each other. Kings and peoples give their assent to the law of nations through custom, not typically by positive agreement. Long observance of a norm in the relations between states gives it the force of law. In contrast to natural law, which confers its basic rights and obligations to all persons whether in a private or public capacity, the law of nations applies to relations between sovereign entities (cf. JBP Prol. 40; De Indis fol. 12ff). It deals, accordingly, largely with matters of state, such as embassies, treaties, and the special privileges of sovereigns in waging war. This system of customary law, in turns out, makes the legal position of sovereigns radically different from that of private actors in the ‘universal society’ established by natural law.

b. Just War: Jus ad Bellum

The mutual influence of the laws of nature and nations can be seen in both the resort to war (traditionally called the jus ad bellum) and in its conduct (jus in bello). The only just grounds for resorting to war are those that involve the pursuit of a right. Among such pursuits, Grotius identifies three kinds: self-defense, the recovery of property and punishment. Each of these has its basis in natural law, though the particular rights at issue might arise from other sources, such as the law of nations. The right of self-defense arises from the natural permission every person has to protect against injury (II.I.iii). If our primary concern is self-preservation, we could not take the risk of living among other people without reserving the permission to protect ourselves from them. The right of defense extends not only to one’s life, but also to one’s body and property. Grotius argues that killing in defense of one’s body is justifiable even if the assailant’s objective is not to kill but to maim or rape ( The reason is that one can never trust that a physical assault will not result in death (though it is unclear in Grotius’ treatment of rape whether it is the victim’s life or interests of men in her ‘chastity’ that is the justifying concern). There are two constraints on justified self-defense: that the attack is imminent and certain (II.I.v). Defense is a just cause that applies only to immediate danger. Even property, however, may be defended with lethal force, with the further constraint that such force is necessary for retaining it (II.I.xvi).

Apart from defense, war may be waged in order to recover one’s rights or to punish the offender. Acting under these just causes will often entail being the one to initiate violence. Grotius argues that this breach of peace is not anti-social (and hence in violation of natural justice) because the initiator is only demanding what the other party already owes (I.II.i.5-6) – they are not violating but upholding the system of rights. Recovery of property applies not only to moveable things and territory, but also to rights over persons (such as rightful subjects or slaves), rights to actions (such as the fulfillment of contracts), and compensation for damages. All of these might be claimed by natural right, though the particular claims might be shaped by prevailing domestic systems of property or by the law of nations. This single heading yields an expansive range of cases in which war is a just option for enforcing rights. Punishment multiplies such cases. When someone willfully violates a right, they become obligated not only to make restitution but to endure punishment equivalent to their crime. Any law-respecting person (as explained above) may execute this punishment, in principle, though a number of factors will tend to limit international punishment. Due to the high risk of harming the innocent in pursuit of the guilty, punitive wars are permissible only for serious crimes (II.XX.xxxviii). In most circumstances, only sovereign governments will be permitted to execute the punishment since individual citizens would have transferred this natural right to their state (see II.XX.xxiv and II.XX.xl; cf. De Indis, fol. 40-40’). Public authorities, therefore, can lay claim to special punitive causes such as the punishment of crimes against natural society (see above) and anticipatory defense. Whereas only an actual attack can justify self-defense, a plot to attack, once set in motion, is already a crime (II.I.xvi). Under the cause of punishment, a state may resort to preemptive warfare which defense alone could not justify. Finally, every exercise of punishment must be limited to the achievement of certain goods. While the right to punish has a retributive justification rooted in the offender’s obligation to endure it, the exercise of this right ought to be governed by consequentialist considerations. The good of the offender, of the victim and of the broader society, are all relevant benefits that need to be weighed against the harms to each of these (II.XX.iv-ix). Especially when the consequences of punishment include a broader war, these considerations may urge clemency, restraint or even pardon (II.XX.xxii-iv and xxxiv-xxxvi; see II.XXIV.ii-iii).

There is a general pattern of argument—that people are permitted, in the strictness of justice, to use violence in a great many cases that will nonetheless call for moderation in the name of humanity and peace—that characterizes the whole of De Jure Belli ac Pacis. Justice is a crucial virtue, as the maintenance of society and respect of law require it, but its guidance is limited to these minimal aims. To know what the laws ought to be and to decide when and how far to exercise one’s rights, it becomes necessary to follow the promptings of equity, humanity and prudence. These “virtues which have as their object the good of others” (I.I.viii) not only serve to measure the proper severity of punishments but also to determine whether war for a punitive cause is warranted at all. Humaneness imposes a moral limit, too, in how far one ought to press rights to property, so as not to use market power to squeeze people (II.XII.xvi) or to withhold vital information when making contracts (II.XII.ix). Even in self-defense, the resort to war can have humanitarian consequences that speak strongly against making full use of one’s right (II.I.iv, viii, ix and xi). It would be a grave error, Grotius warns, to think that “where a right has been adequately established, either war should be waged forthwith, or even that war is permissible in all cases” (II.XXIV.i). The resort to war must be squared not only with justice but with humanitarian concerns, especially for its impact on the lives of innocent people. This loving regard for others that aspires to universality is what Grotius held up, in his works on religion, as the great ethical appeal of the Gospel, and De Jure Belli instructs its readers to recognize that not only humanity but also God calls them to love, forbearance and restraint.

c. Just War: Jus in Bello

The meshing of these normative standards of justice and humanity is especially pronounced in Grotius’ treatment of the conduct of war in Book III of De Jure Belli. The natural law provides but one basic rule for the conduct of war: “things which lead to an end receive their intrinsic value from the end itself” (JBP III.I.ii). That is, if one has a right to resort to war, then one has a right to conduct the war by whatever means are necessary to vindicate the just case. Grotius finds natural justice an unsatisfactory basis for the ethics of combat for two main reasons: (i) it permits inhumane and intemperate actions on the part of those who fight under a just cause, and (ii) it provides no guidance whatsoever for those who fight under an unjust cause. The answer to the first deficiency is Grotius’ account of temperamenta, discussed below. The second deficiency finds its solution in the law of nations. Grotius recognizes that while no war can be naturally just on both sides—a right on one side precludes a right on the other—wars may be either unjust on both sides or justifiably believed to be just on both sides. In either case, there are belligerents for whom natural justice provides no guidance other than, ‘your cause is unjust: stop fighting.’ Grotius resigns himself to the realism that, aside from exceptional cases, most states will not admit to the injustice of their cause and simply stop fighting. The longer such states fight, the more injustices they pile up by resisting the just party. Before long there would be no limit to the punitive war that could be prosecuted against the unjust state (see III.IV.iv). Grotius suggests that nations, recognizing the perils of this situation, established a custom of holding both parties in a war to have equal standing on the battlefield. That is, the law of nations permits to both sides (regardless of the justice of their cause) all the actions that the natural law would permit to the just.

The customs of warfare under the law of nations turn out to be extremely permissive. Tracking the prevailing practice of states, the customs permit everything from the slaughter of innocents to the taking of slaves and the looting of civilian property. License to conduct warfare in this way is the special privilege of sovereigns who have ‘solemnized’ their war under the law of nations. Indifferent to the substantive justice of a state’s cause, the law of nations insists instead on certain formalities—a public declaration by the sovereign authority—to give the belligerent its legal status in a solemn war (I.III.iv and III.III). While Grotius defends this status as a way of restoring normal relations between sovereigns at the end of war, he insists that even kings remain accountable to natural justice. The law of nations is derived from human will, and the license it gives in solemn wars cannot contradict the requirements of natural law. The license amounts to an agreement among nations not to punish each other for certain acts (III.IV.ii-iii). So, after many lengthy chapters detailing the range of actions permitted by the law of nations, Grotius takes an abrupt turn, telling the reader that he must now retrace his steps and “deprive those who wage war of nearly all the privileges which I seemed to grant, yet did not grant to them” (III.X.i). Those waging a solemn war may have the privilege of impunity under human law, but a ‘sense of shame’ ought to instill a respect not only for the ‘external’ judgments of the courts but for the ‘internal’ judgments of conscience (III.X and III.XI.i-ii). Those waging an unjust war will be accountable to God, and they have an (unenforceable) obligation to make restitution to those they have wronged. Even those waging war for a just cause should observe the limits of natural justice by sparing the innocent and pursuing only those war aims that are necessary to securing one’s rights. Conducting war merely within the bounds of the law of nations may obtain impunity, but it brings no badge of honor.

What makes kings and peoples worthy of honor is their observance of temperamenta: moderation and restraint in pursuing their just claims. Such restraint comes out of a respect for justice—by restricting the means of war to only what is necessary to achieving the ends—and also out of a sense of humanity. This humane concern for others seeks to limit the impact of war on the innocent and even those fighting on the opposing side (see, for example, III.XI.viii, XII.viii, and XIII.iv). It requires in many cases the remission of punishment, to forgiveness of burdensome war debts, and a preference for restoring local sovereignty rather than imposing imperial rule. At all events, one must uphold good faith in agreements made with the other side in order to build the basis for normal relations after the war (III.XXI-XXV). Humanity holds in view not only the aim of restoring rights but of restoring peace (see III.XXV.ii-iii). Justice might condone war against injuries that threaten the basis for living together in society, but a sense of humanity is fostered by the recognition that we must live together again.

5. Scholarly Interest in Grotius

In the century following his death, Grotius’ works came to be viewed as pivotal in the development of early modern moral and political philosophy. Jean Barbeyrac, in his 1749 essay on the emerging Science of Morality, described Grotius as “breaking the ice” of medieval dogma to make way for a rational approach to ethics. The natural law philosophy of the seventeenth and eighteenth centuries—from Pufendorf to Locke, Vattel and Thomasius—took the framework of De Jure Belli ac pacis as a point of departure. This canonical status made Grotius required reading for Enlightenment intellectuals, such that Rousseau would come to describe him in Emile, however critically, as “the master of all the savants” and Adam Smith would credit him in his lectures on jurisprudence as giving the world the most systematic treatment of the subject to date. The 21st century has seen a renewed debate among scholars over the extent of Grotius ‘originality’ in moral thought and in what it consists: the purported secularism of his approach, its rationalism, its refutation of skepticism, its account of obligation, or a variety of other candidates. Beyond these disputes, recent historians of moral and political philosophy have taken special interest in Grotius’ conception of natural rights, his theory of punishment, and his accounts of property and state sovereignty.

Grotius’ legacy, however, is most strongly connected to his contributions to international legal theory and the laws of war. Interest in Grotius saw a revival in the late nineteenth century amid efforts to articulate and institutionalize norms of international law. The peace societies of the time, closely bound up with the international women’s suffrage movement, traced back to the Grotius the evolving conscience of the ‘civilized’ world towards justice and mercy in international conflicts. Andrew Dickson White, the U.S. delegate to the 1899 Hague Peace Conference, regarded Grotius—whom he classed among the world’s Seven Great Statesmen in the Warfare of Humanity with Unreason—as providing the “real foundation of the modern science of international law.” While the claim to being ‘father’ of this law was as disputed as it was common, and despite many critical views of this work—in his 1925 history of political philosophy, Charles Vaughan had called De Jure Belli a “nest of sophistries and contradictions”—Grotius came to have a canonical status in international legal thought. By the end of the Second World War, the legal scholar Hersch Lauterpacht was able to discern a ‘Grotian tradition in international law’ rooted in commitments to the rule of law, to norms beyond positive law, and to the human capacity for moral progress in the law. Grotius continues to be most widely known within the study of just war theory and international law, most notably for the contribution of Mare Liberum to the modern law of the sea.

The preeminence of Grotius in the field of international law exerted its influence as well on the development of international relations theory. Theorists of international relations have commonly viewed Grotius as providing a distinctive conception of international society that provides a middle way between Hobbesian anarchy and Kantian cosmopolitanism. In this schema of ‘realist,’ ‘rationalist,’ and ‘revolutionist’ theories, proposed by Martin Wight and pursued in the work of Hedley Bull and others of the ‘English School’ of international relations theory, the Grotian tradition provides a rationalist account of international society. While rejecting the idea that there are common interests among states sufficient to underpin a supranational authority, the Grotian system identifies a ‘solidarity’ of interests around basic principles of order (such as mutual independence, adherence to promises, the limitation of war) that enables sovereign states to constitute their relations as a (limited) community rather than as a contest governed by the dynamics of power alone.  The association of Grotius with this strain of thought has given his work enduring interest in contemporary international theory.

While reaching the greatest prominence in international thought, the early 21st century scholarship on Grotius has a markedly interdisciplinary character. His works have received considerable attention from political theorists and historians of political thought, as well as by those studying his contributions to moral philosophy, theology and literature. Indeed, the eclecticism of Grotius’ thought pushes beyond modern disciplinary boundaries and springs up continuing dialogues across fields and borders.

6. References and Further Reading

Included in the Primary Sources are selected works of Grotius with a preference for most recently in-print English editions. (Note: references to De Jure Belli in the article provide the book, chapter and section numbers, e.g., II.XXIV.i.). The selected secondary sources include references from the article as well as suggested directions for further reading. The interested scholar will also want to consult the regularly published journal of Grotius studies, Grotiana.

a. Primary Sources

  • Grotius, H. (2006). De Jure Praedae Commentarius / Commentary on the law of prize and booty. Indianapolis, Liberty Fund.
  • Grotius, H. (1994). “Commentarius in Theses XI”: an Early Treatise on Sovereignty, the Just war, and the Legitimacy of the Dutch Revolt, P. Lang.
  • Grotius, H. (2004). The Free Sea. Indianapolis, IN, Liberty Fund.
  • Grotius, H. (1988). Meletius. Leiden, Netherlands, Brill.
  • Grotius, H. (1990). Defensio Fidei Catholicae de Satisfactione Christi, adversus Faustum Socinum Senensem. Assen/Maastricht, the Netherlands, Van Gorcum.
  • Grotius, H. (2001). De Imperio Summarum Potestatum circa Sacra. Studies in the history of Christian thought, v. 102. H.-J. v. Dam. Leiden, Brill.
  • Grotius, H. (1926). The Jurisprudence of Holland. R. W. Lee. Oxford, Clarendon Press.
  • Grotius, H. (2005). The rights of war and peace. Indianapolis, Liberty Fund.
  • Grotius, H. (1962). De Jure Belli ac pacis libri tres / The Law of War and Peace. Indianapolis, Bobbs-Merrill.
  • Grotius, H. (2012). The Truth of the Christian Religion. Indianapolis, Liberty Fund.

b. Secondary Sources

  • Borschberg, P. (1994). “Critical Introduction.” “Commentarius in Theses XI”: an Early Treatise on Sovereignty, the Just War, and the Legitimacy of the Dutch Revolt. H. Grotius, P. Lang.
  • Brett, A. (2002). “Natural Right and Civil Community: The Civil Philosophy of Hugo Grotius.” The Historical Journal 45(01): 31-51.
  • Bull, H., B. Kingsbury, et al. (1990). Hugo Grotius and International Relations. New York, Clarendon Press.
  • Dumbauld, E. (1969). The Life and Legal Writings of Hugo Grotius. Norman, University of Oklahoma Press.
  • Forde, S. (1998). “Hugo Grotius on Ethics and War.” American Political Science Review 92(3): 639-648.
  • Haakonssen, K. (1985). “Hugo Grotius and the History of Political Thought.” Political Theory 13(2): 239-265.
  • Heering, J. (2004). “Hugo Grotius’ De Veritate Religionis Christianae.” Hugo Grotius as Apologist for the Christian Religion: a Study of his Work De veritate Religionis Christianae, 1640. J. Heering. Leiden, Brill: 41-52.
  • Keene, E. (2002). Beyond the Anarchical Society: Grotius, Colonialism and Order in World Politics, Cambridge University Press.
  • Kinsella, H. M. (2006). “Gendering Grotius: Sex and Sex Difference in the Laws of War.” Political Theory 34(2): 161.
  • Meijer, J. (1955). “Hugo Grotius’ “Remonstrantie”.” Jewish Social Studies 17(2): 91-104.
  • Nellen, H. a. R. E., Ed. (1994). Hugo Grotius Theologian: Essays in Honor of G.H.M. Posthumus Meyjes. New York, Brill.
  • Onuma, Y., Ed. (1993). A Normative Approach to War: Peace, War, and Justice in Hugo Grotius. Oxford, Clarendon Press.
  • Schneewind, J. B. (1998). The Invention of Autonomy: A History of Modern Moral Philosophy. New York, Cambridge University Press, ch. 4.
  • Straumann, B. (2006). “The Right to Punish as a Just Cause of War in Hugo Grotius’ Natural Law.” Studies in the History of Ethics.
  • Suárez, F. (1944). De Legibus. Selections from Three Works. New York: Clarendon Press.
  • Thomson, E. (2009). “The Dutch Miracle, Modified. Hugo Grotius’s Mare Liberum, Commercial Governance and Imperial War in the Early-Seventeenth Century.” Grotiana 30(1): 107-130.
  • Tuck, R. (1993). Philosophy and Government, 1572-1651. New York, Cambridge University Press, ch. 5.
  • Tuck, R. (1999). The Rights of War and Peace : Political Thought and the International Order from Grotius to Kant. New York, Oxford University Press, ch. 3.
  • van Gelderen, M. (1993). “Vitoria, Grotius and Human Rights: The Early Experience of Colonialism in Spanish and Dutch Political Thought.” Human Rights and Cultural Diversity. W. Schmale. Goldbach, Germany, Keip Publishing: 215-238.
  • van Gelderen, M. (2006). ‘So Meerly Humane’: Theories of Resistance in Early-Modern Europe. Rethinking the Foundations of Modern Political Thought. A. S. Brett, J. Tully and H. Hamilton-Bleakley. New York, Cambridge University Press: 149-170.
  • van Ittersum, M. J. (2006). Profit and Principle : Hugo Grotius, Natural Rights Theories and the Rise of Dutch Power in the East Indies, 1595-1615. Leiden, Brill.
  • van Ittersum, M. J. (2010). “The Long Goodbye: Hugo Grotius’ Lustification of Dutch Expansion Overseas, 1615-1645.” History of European Ideas 36: 386-411.
  • Vitoria, F. d. (1991). On the American Indians. Political writings. A. L. J. Pagden. New York, Cambridge University Press.
  • Vitoria, F. d. (1991). On the Law of War. Political writings. A. L. J. Pagden. New York, Cambridge University Press.
  • Vreeland, H. (1917). Hugo Grotius, the Father of the Modern Science of International Law. New York, Oxford University Press.
  • Wilson, E. M. (2008). The Savage Republic: De Indis of Hugo Grotius, Republicanism, and Dutch Hegemony within the Early Modern World-System (c. 1600-1619), Martinus Nijhoff Publishers.

Author Information

Andrew Blom
Central Michigan University
U. S. A.