Medieval Political Theory

John Kilcullen. Handbook of Political Theory. Editor: Gerald F Gaus & Chandran Kukathas. 2004. Sage Publication.

Every intellectual discipline constructs and reconstructs its own history, as writings not previously regarded as important get into reading lists and others fall out. Until recently students of political theory were urged to read Plato and Aristotle, and then Hobbes and Locke, but nothing, or very little, between the Greeks and the early moderns. Those who have ventured into this gap have found that, at least from the thirteenth century, there was a good deal of political theory and clear links with the theories of the seventeenth century. The seventeenth-century writers are better understood if we are also familiar with the work of their predecessors, who are in any case as much worth reading as they are. An interesting task for historians of political theory, and for political theorists, is to integrate the study of medieval thought into the discipline.

As with many of the seventeenth-century classics, the medieval contributions to political theory were works ‘of occasion.’ They were produced by academics for academically trained readers, but their authors did not produce them as part of their teaching duties. They were written in an attempt to intervene in the public affairs of the time, especially in controversies within the Church and between churchmen and lay rulers. Given the relatively slow reproduction of manuscripts before the introduction of printing, these writings probably had little impact on the public events that prompted them (except perhaps so far as their arguments circulated orally), but they were collected and studied by university-educated professionals in law and government, ecclesiastical and secular, and over time they occupied the libraries and the minds of institutions and individuals likely to be involved in similar events in the future. (On the dissemination of political writings and the social position of people interested in them, see Miethke, 1980; Oui, 1979; Miethke, 2000b.) Some of these medieval writings were produced in the early days of printing, and in the seventeenth century there were several major printed collections (notably Goldast, 1611-114; Dupuy, 1655). Protestants as well as Catholics read these works (Goldast was a Protestant), and they exercised an influence throughout Europe (see Oakley, 1962; 1969; 1996). The parallels between, for example, Hobbes and Marsilius, and Locke and Ockham, are striking.

One of the main tasks set itself by the reformed papacy of the eleventh century was to free Church offices from the control of the aristocratic families who also held military and political power, and beyond that to make Christianity the effective conscience of rulers. This was indeed a ‘papal revolution,’ and it led to a ‘crisis of Church and state’ that lasted into modern times (see Berman, 1983; Tierney, 1980). Its early stage is called the ‘Investiture Contest,’ which included Pope Gregory VII’s deposition of the Emperor Henry IV. During the thirteenth century there were conflicts between popes and emperors, including Pope Innocent IV’s deposition of the Emperor Frederick II. There were disagreements over the constitution of the Empire whether election by the electoral princes gave the emperor-elect his power, or whether this required approval by the pope—and over the relationship between the Empire and the Kingdoms of France, England and Spain. The increasing wealth of the Church attracted careerists, and also provoked critics who advocated a return to the poverty of the Apostles. The rise of the mendicant orders, especially the Franciscans, prompted controversy about poverty as a religious ideal, which led to works about property which are among the sources of seventeenth-century theories of property (see Lambertini, 2000; Kilcullen, 2001b). The support which the popes gave to the mendicant orders provoked opposition from bishops and parish clergy, which led to controversy about the powers of the pope within the Church (see Congar, 1961). There were disputes between Church authorities and secular rulers about whether the clergy should be exempt from taxation and from the ordinary criminal courts, and whether money collected by the local churches should be used by the papacy to finance not only crusades against the Saracens but also military campaigns in Europe. A number of these disputes moved toward a climax in the late thirteenth century, when studies in philosophy, law, and theology were at a high level of activity in the universities. From near the end of the thirteenth century until the middle of the fourteenth there was a complicated and connected series of debates involving Pope Boniface VIII, King Philip the Fair of France, Pope John XXII, the ‘Roman Emperor’ Ludwig of Bavaria, the Franciscan order and the University of Paris, in the course of which theologians produced many treatises concerning the relationship between religion and secular government, the constitution of the Church, and the constitution of secular government, drawing on the resources not only of theology but also of the law and Aristotelian philosophy. The writings produced during this period became relevant again at the end of the century with the ‘Great Schism’ (1378-1417), which prompted the ‘conciliar’ movement. The Council of Constance resolved the schism by removing three rival popes and appointing another.

Since the nineteenth-century revival of interest in medieval intellectual history, all these matters have been closely studied. Libraries have been searched for manuscripts and new editions have been made, many important writings have been translated from Latin, interpretive studies have been produced in many languages. There is not enough room to survey in this chapter more than part of the field. I will concentrate on what I see as a central theme, the relationship between religion and secular government, restricting myself to the crucial period between Thomas Aquinas and William of Ockham.

The Spiritual and Temporal Powers


In the classical world there was no separation between religion and politics. Aristotle included religion among the functions of a state (Aristotle, Politics, VII.8, 1328 b4-15); the Roman Emperor was called by the religious title ‘Pontifex’ (a title later assumed by the pope), and the Roman law attributed religious powers to the state (see Ullmann, 1974: 7). But during the early middle ages in Western Europe a separation developed between Church and state, or—in the language of the time—between priesthood and kingship. The classic expression of this separation was in a letter sent in 494 by Pope Gelasius I to the Emperor Anastasius:

Two there are, august emperor, by which this world is chiefly ruled, the sacred authority of the priesthood and the royal power. Of these the responsibility of the priests is more weighty, in so far as they will answer for the kings of men themselves at the divine judgment… [I]n the order of religion… you ought to submit yourselves [to priests] rather than rule… [T]he bishops themselves… obey your law so far as the sphere of public order is concerned. (translated Tierney, 1980: 13-14)

This document was later incorporated (in part and in association with material from Pope Gregory VII) into Gratian’s Decretum as the canon Duo sunt (dist. 96, c. 10, Friedberg, 1879: I, 340; translated Tierney, 1980: 13-14). The separation of powers may have developed in fact simply because the earliest exponents of the Christian religion did not possess political power. However, another canon, Cum ad verum (also based on a letter of Gelasius, as quoted by Pope Nicholas I), suggested deeper reasons for it, namely that mutual limitation of their powers would restrain the pride of priest and emperor, and that those on God’s service (the clergy) should be kept free of worldly entanglements (dist. 96, c. 6, Friedberg, 1879: I, 339; translated Tierney, 1980: 14-15; on the materials from Gelasius in the Decretum see Watt, 1965: 12-33).

From these and other passages handed down by Gratian, medieval lawyers and theologians arrived at a view of their world as containing two orders of power, the priesthood culminating in the pope, and the lay government culminating in king or emperor. These two kinds of power were unequal in dignity, the spiritual being superior. Although they were separate, there was no ‘wall of separation.’ (The phrase seems to have been used first by Hooker, 1989: 131, who rejected the idea.) They were expected to co-operate with one another. In particular, the temporal power was required by the spiritual, on pain of spiritual sanctions (excommunication, interdict, etc.), to support its spiritual authority, for example, by eradicating heresy. From time to time kings or emperors acted to reform and purify the Church. At the time it was not assumed that in one territory there would be just one agency with a monopoly of the legitimate use of force (an idea first proposed by Marsilius). It was tacitly assumed that the Church had an inherent right to coerce—in fact, some theologians, perhaps under the influence of the Aristotelian idea of a ‘perfect’ (i.e. self-sufficient) society, explicitly held that the Church, being self-sufficient, could coerce its members; thus a cleric might be imprisoned as a punishment by his bishop, without needing the permission of the secular ruler. It was thought that the clergy should not engage in any cruel coercion, ‘judgements of blood,’ but it was not thought that the influence of severe punishment could always be dispensed with. Hence the requirement of aid from the secular ruler, who would use methods of coercion which the clergy could not use. Gratian quotes Isidore of Seville, according to whom princely power exists within the Church ‘so that what priests are not strong enough to effect by word of teaching, this power might command by terror of discipline’ (C. 23, q. 5, c. 20, Principes, Friedberg, 1879: I, 936). When John of Paris points out that with reference to heretics Paul said ‘avoid,’ not ‘burn,’ and suggests that beyond such spiritual penalties as avoidance the spiritual power cannot go (1971: 161), he is supposing that the spiritual power may well require the temporal power to go further (1971: 143). (In practice the wielders of the material sword seem to have kept control: see Watt, 1988: 387-99, on practice in England and France.)


Another key idea handed down by Gratian was that the pope enjoyed plenitudo potestatis, ‘fullness of power’ (C. 3, q. 6, c. 8, Friedberg, 1879: I, 739; see Rivière, 1925). This meant, not that the pope had every conceivable power, but that the pope was the source of all ecclesiastical jurisdiction, having authority to intervene directly in any matter anywhere within the Church; thus within a diocese the pope could do directly anything the local bishop could do. (As Giles of Rome explained (see below), a cause that can do directly whatever it can also do through secondary causes has ‘fullness of power.’) By virtue of ‘fullness of power,’ the thirteenth-century popes insisted that the mendicants (Franciscans, Dominicans and others) should be permitted to preach and minister anywhere, with or without the support of the local bishop. The idea that the pope can exercise directly any of the powers that Christ has given to the Church does not infringe the principle of separation of spiritual and temporal power, as long as it is accepted that Christ did not give temporal power to the Church.

However, during the thirteenth century the papal claim to fullness of power came to be extended to temporal matters. Pope Innocent III wrote: ‘Paul… writing to the Corinthians to explain the plenitude of power, said, “Know you not that we shall judge angels? How much more the things of this world?” Accordingly [the papacy] is accustomed to exercise the office of secular power sometimes and in some things by itself sometimes and in some things through others’—the ‘others’ being the kings and emperors. The popes were thinking of the Church as coextensive with the human community in Christian parts of the world, with the pope as its head on earth, the secular rulers being his agents in temporal matters and the clergy his agents in spiritual matters. The two powers, often referred to as the ‘two swords,’ were generally said both to belong to the pope, though it was said that he had the ‘exercise’ of the spiritual sword only. He was said to entrust the exercise or ‘administration’ of the temporal sword to the secular ruler, while he kept its ‘authority,’ meaning that the secular ruler used his sword ‘at the command’ (ad nutum) of the pope (Tierney, 1980: 93-4, 120-4). The withholding from the pope of the exercise of the temporal sword signified some restriction upon papal intervention in secular affairs, namely that he could not act directly; but the claim that the temporal sword ‘belonged to’ the pope and that he had its ‘authority’ implied a power to give binding directions to the temporal ruler, leaving no autonomous sphere of temporal power.

The principle of Duo sunt, the separation of powers, was not simply abandoned. The popes presented their interventions in temporal matters as exceptional. Canon lawyers, including Pope Innocent IV himself in his capacity as lawyer commenting on the decretals, drew up lists of the exceptional circumstances in which the spiritual power might intervene in temporal affairs (Tierney, 1980: 153 4; cf Watt, 1965: 68-9). The most comprehensive rubric for intervention was ratione peccati, ‘by reason of sin’: if a secular ruler’s actions are unjust, then this is a sin against which the spiritual power may act. As the pro-papal writer Giles of Rome remarked, this rubric ‘is so broad and ample that it may embrace all temporal disputes whatsoever’ (1986: 167-8). It began to look as if very little, if any, sphere of autonomy was being left for the temporal power. This especially seemed so from the main line of argument underlying papal claims: the pope is Christ’s vicar (place-holder, substitute) on earth, Christ is God, and God is lord of all; therefore the pope is lord of all (see, for example, the passage from Innocent IV in Watt, 1965: 66-7).

The claim to ultimate papal supremacy will no doubt seem objectionable to the modern reader, but there are elements in it with which we should sympathize. We can agree, I assume, that everything governments do is subject to moral assessment there is no ‘autonomous sphere’ of government action exempt from moral assessment; and we can perhaps agree that citizens and others make their moral assessment of government and other social institutions by applying moral values or principles that are independent of government and popular opinion (‘natural law’). We can also agree that there may be people whose opinion on moral matters is especially worth considering, either because they are factually well informed or because they have thought much about ethical issues (and among these we may include the clergy, unless we think that Christianity is actually misleading); that such people should speak out when they believe government is doing wrong; that in extreme cases they might be justified in calling on people to reject a government, either by electing another, or by disobeying, or by rebellion. The popes went beyond all this, however, in claiming that their moral assessments of government should be accepted without dispute and acted on obediently.6 It was not supposed that in such matters papal judgements were infallible. Indeed, it was envisaged that a pope might fall into heresy or into serious and persistent sin, and in such cases the pope could be judged and deposed (Gratian, Decretum, dist. 40, c. 6; Tierney, 1980: 124-6). But a pope still in the papal office must be obeyed, apparently without any possibility of objection or resistance: the pope ‘judges all and is judged by none’ (cf Hugh of St Victor, Tierney, 1980: 94-5). There was in fact a good deal of resistance but at the risk of excommunication or worse; perhaps the safest form of resistance was to accuse the pope of heresy, as Philip IV did Pope Boniface.

The Debate on the Power of the Pope

Toward the end of his life William of Ockham expressed the opinion that zeal for Christianity required that ‘in these dangerous times’ all the learned should investigate the basis and extent of papal power, because of the infinite evils that ignorance of it has brought about among Christians from ancient times (1998: 136). Ockham had been active in this investigation for some 20 years, and debate on the extent of papal power had already been in progress since the time of Boniface and earlier. In this chapter it is not possible to do more than sketch the contributions of a few writers. Five must suffice: two of them, namely Thomas Aquinas and Giles of Rome, extended papal power to temporal matters; three, namely John of Paris, Marsilius of Padua and William of Ockham, opposed this extension.

Thomas Aquinas

Thomas Aquinas gives two significantly different accounts of the relationship between the two powers, though in both accounts the secular power is subjected to the spiritual. In an early writing, Scriptum super libros sententiarum, he asks, ‘When two authorities conflict, how should we decide which to obey?’ He answers that if one authority originates totally from the other (as, he says, the authority of a bishop derives from the pope), greater obedience in all matters is due to the originating authority. If, however, both of the authorities in conflict originate from a higher authority, the higher authority will determine which of them takes precedence on which occasion. Spiritual and secular power, he says, both come from God, so we should obey the spiritual over the secular only in matters which God has specified, namely matters concerning the salvation of the soul; in civic matters we should obey the secular power—‘unless,’ Thomas immediately adds, ‘spiritual and secular power are joined in one person, as they are in the Pope, who by God’s arrangement holds the apex of both spiritual and secular powers’ (the relevant passage of the Scriptum is translated in Phelan and Eschmann, 1978: 106-7). This seriously restricts the application of the doctrine of Duo sunt: at the lower levels the spiritual and temporal powers are held by different individuals, but at the highest level they are both held by the same man.

In another writing of uncertain date, De regno,7 Thomas applies Aristotle’s teleological thinking to politics. A polity has an end, purpose or goal, which may be sought in a variety of ways, effectively or not, and it is a composite entity consisting of many individuals with their own individual purposes. For both reasons there is needed some directing or steering agency or government (gubernatio in Latin means literally ‘steering,’ as of a ship) to guide the potentially conflicting individuals effectively to their common goal. The goal is in some way single otherwise the polity will disintegrate. Every being is in some way one; a composite entity has a unity of order, i.e. of direction to a single end. In preserving its being, therefore, the steering agency has to preserve the polity in peace and unity by ordering it to a common goal. There is a hierarchy of goals, that is, there are intermediate ends which are also means to higher ends. A polity exists to secure its citizens’s lives, but above living there is living well, i.e. virtuously, and above that there is living so as to attain the ‘beatific vision’ of God (the Christian heaven). If all these ordered ends were attainable simply by human effort, the one supreme directing agency would be concerned with them all; however, to attain the beatific vision requires ‘grace,’ i.e. God’s special help, which natural human activity cannot earn. God’s Church is a human agency that God has established as a means to grace, especially through the sacraments. Hence there is a distinction between secular government using naturally available means to guide citizens to their final goal, and ecclesiastical government using supernatural means, the sacraments. This provides a theological rationale for the separation called for by Duo sunt: the distinction between the two powers is based upon a distinction between natural and supernatural means of attaining the goals of human existence. Secular government has the task of leading citizens toward the beatific vision, by way of the lower goals of securing the essentials of physical life and, above that, of virtuous living; but it cannot attain the highest goal, the beatific vision, because natural human means are not adequate. On this view also the secular power is subordinated to the spiritual. Secular rulers must be subject to the pope, ‘for those to whom pertains the care of intermediate ends should be subject to him to whom pertains the care of the ultimate end’ (Thomas Aquinas, 1978: 3-13, 58-67).

Giles of Rome

In his On Ecclesiastical Power (1302), Giles of Rome argues that all dominium (lordship), including ownership of property as well as governmental power or jurisdiction, belongs primarily to the Church, and in particular to the pope, though the ‘busyness’ (sollicitudo) of administering temporalities is allotted to the laity, so as to leave the clergy free for spiritual matters. To establish the primary lordship of the pope Giles gives many arguments. The following are the more significant.

(1) Whether bodily health is served by bodily goods does not depend on whether they are lawfully possessed, but spiritual health does depend upon whether bodily goods are lawfully possessed. Hence the bodily physician has no concern with rightful possession, and hence does not have lordship over his patient’s bodily goods, but the spiritual physician does have. The spiritual physician has such power over temporal goods that he must be called their lord. ‘For he who judges a thing is always lord of the thing judged’ (Giles of Rome, 1986: 86, 87, 97-8).

(2) According to Augustine in De civitate dei IV.4 (1998: 147), without justice, kingdoms and empires are great bands of robbers; and in De civitate dei II.21 (1998: 80) Augustine says that there is no true justice except in the commonwealth whose founder and ruler is Christ. In De civitate dei XIX.21 (1998: 950-2) Augustine argues that the commonwealth of the Romans was not a true commonwealth because it did not attain true justice, since the Romans did not worship the true God. Similarly, Giles of Rome maintains that non-Christians cannot justly have lordship: ‘Since you are unjustly withdrawn from Christ your Lord, everything is justly withdrawn from your own lordship’ (1986: 69; cf 1986: 92). As far as just and worthy possession is concerned, then, lordship is conferred by membership of the Church, which (Giles assumes) implies that the Church has pre-eminent lordship (1986: 65-95).

(3) The Church has power to excommunicate, but possessions are held by virtue of laws which rest upon pact, which rests upon the communion of men with one another. If the Church can cause a man to be excluded from the community of the faithful—and Giles supposes that there is no genuine community of men apart from the community of the faithful—then the Church can cause him to be deprived of the foundation upon which all legal transactions are grounded, and he will not be able to claim lordship over anything (1986: 98-102).

In the last part of his book Giles undertakes to answer objections. Christ says, ‘Render to Caesar the things that are Caesar’s and to God the things that are God’s’ (Matthew 22.21), implying that some things are Caesar’s. Giles answers that just as God normally leaves things to take their own course under the ‘common law’ (i.e. the ordinary laws of physics), although he has power to intervene by miracle at any time, so the pope normally allows secular lords to act under the common laws, although he has the power to intervene directly at any time by virtue of his ‘fullness of power.’ A cause that can do directly whatever it can also do through secondary causes has ‘fullness of power’ (1986: 187-8). The pope has fullness of power in the sense that he can do directly anything that can be done by any agency within the Church (1986: 188); this includes secular government, because, as the arguments above have shown, outside the Church there can be no lordship. However, just as God normally allows secondary causes to take their course and only occasionally intervenes directly (i.e. miraculously), so the pope normally leaves secular government to laymen (1986: 189). Thus, even if ultimate temporal authority belongs to the pope, a dualism of a sort is still possible: the pope may relate to secular government in the same way as in modern times a state (provincial or national) government relates to city government, normally leaving city affairs to the lower level of government, but being able to intervene with full constitutional right when it sees fit.

John of Paris

On Royal and Papal Power (1302) by John of Paris is also concerned with lordship (see: Rivière, 1926; Leclercq, 1942; John of Paris, 1971; Tierney, 1998). John denies that the pope is the supreme lord on earth in both spirituals and temporals. He rejects the argument that since the pope is Christ’s vicar, and Christ is God, and God is lord of all, therefore the pope is lord of all (1971: 100). According to John, this argument breaks down twice. First, the pope is the vicar of Christ as man (not as God), and Christ as man was not lord of all. Second, even if Christ as man had been lord of all, Christ did not give all of his own powers to his vicar: in particular there is no evidence that he gave him universal dominium on earth (1971: 106-10, 115-16; William of Ockham, 1992: 66-7, makes the same reply). God is supreme lord in both spirituals and temporals, but on earth there is no individual who is God’s vicar in both at once. The secular ruler is God’s vicar in temporals, and the pope is Christ’s vicar in spirituals.

John reasserts the long standing distinction between the two senses of dominium that Giles had run together, namely ownership of property and jurisdiction; a ruler’s jurisdiction in property disputes does not mean that he has superior ownership over his subjects’s property (1971: 106; cf Giles of Rome, 1986: 86, ‘For he who judges a thing is always lord of the thing judged’). John argues that the pope has jurisdiction in spiritual matters but does not have ownership even of Church property, let alone of the property of laymen. Property is in the first instance acquired by individuals, not by communities; a community acquires its property by donations from individuals, who make their gifts to the community, not to its officers as individuals, and the donors’ intentions must be respected. Church property belongs to some religious community (a monastery, the diocese, the Church as a whole, etc.), and the head of such a community is only an administrator, not an owner. (These points were commonplace: see Leclercq, 1942: 134.) He ought not manage property negligently or corruptly, and if he does he can be deposed. In emergencies the pope may call on individuals and communities to supply resources to assist the common good (1971: 104), and the prince may do likewise (1971: 210). The power to do this does not constitute ownership of their subject’s things.

As for dominium in the sense of jurisdiction, John argues (1) that among Christians the spiritual and temporal powers should be physically distinct, and (2) that the temporal power does not owe its existence to the spiritual power. On the first point, he says that among Christians the temporal and spiritual jurisdictions should be distinct subiecto (i.e. distinct in the persons in whom they are located), which would mean that the pope cannot be both spiritual and temporal ruler. This is the traditional tenet of Duo sunt, and John gives the traditional reasons, emphasizing the argument that the priest should be exclusively devoted to spiritual affairs (1971: 115-18; Hooker, 1989: 129-31, argues against the view that between Church and commonwealth there must be a ‘personal’ separation, a separation ‘in subsistence’). In pre-Christian times there were priests, or persons with priestly functions, who also had temporal power, but under Christianity priests are exclusively priests (1971: 200). (There are echoes here of the canon Cum ad verum, dist. 96, c. 6, and of canonist comment; see Tierney, 1980: 121-2.) His opponents accepted that in respect of their exercise the spiritual and temporal powers are distinct subiecto, but said that the pope ‘possesses’ and has the authority of the temporal sword, which must be exercised on his direction. Against this John argues that it would have been a notable lack of wisdom on God’s part to have given the pope power he was permanently debarred from exercising (1971: 123-6, 129).

On the second point, he says that the temporal power is not established by, or in any way caused by, the spiritual power; both come from God, but neither through the other. The spiritual is in some sense superior, but not as being the cause of the temporal power (1971: 93, 96, 192).

Thus there are separate spheres of jurisdiction, with prince superior to pope in temporal matters and pope to prince in spiritual matters. Both powers have been established by a higher power, God, who has appointed their limits, and the spiritual power is limited to spiritual matters (1971: 93). However, the two powers have some common concerns. The temporal power is not merely corporeal (1971: 182), but exists to further virtuous living as the way to eternal beatitude, so far as this can be done by natural means. At the same time, the spiritual power is concerned for the physical well-being, the survival at least, of the Christian community. Further, John accepts the principle stated in Gratian in a text from Isidore (see above), that sin should be physically punished in this world, which John expects to be done by the temporal power (1971: 143); he also holds that heretics should be compelled to return to the Church (1971: 204). Hence he does not advocate the modern ‘wall of separation’ but distinction and co-operation. Either power may on occasion intervene in the sphere of the other, but each power must use only its own appropriate means of action: this is the basis of the distinction between the two powers. The secular ruler can use only temporal penalties (e.g. seizure of goods, corporeal punishment), and the Church can use only spiritual penalties (e.g. excommunication, interdict).

Indirectly prince and pope may coerce one other. If a pope does wrong spiritually, correction is primarily the business of the cardinals; if a prince does wrong temporally, correction is primarily the business of his barons or peers. The first step in correction is advice and exhortation, but coercive measures may follow, and the other power may intervene (perhaps at the request of cardinals or barons). John distinguishes various cases. If a prince does wrong in spirituals, the pope can use spiritual penalties (e.g. excommunication of those who obey the prince) to influence the people to depose him. If a pope does wrong in spirituals the prince can use temporal penalties (e.g. sequestration of goods of those who obey him) to induce the pope to resign or to induce the people to depose him. (Note that John supposes that the people can depose a pope.) If the prince is delinquent in temporals the barons can call on the Church to support them by spiritual penalties (e.g. excommunication) against those who continue to obey the prince. If the pope is delinquent in temporals, the emperor can directly punish him (unless, as some say, he is exempt not only by privilege granted by the emperor but by divine law; John does not decide this question). In each of these cases pope and prince use only their respective kinds of penalties, spiritual and temporal (1971: 156-61).

The coercion and deposition of a pope was a topical matter, since Philip’s response to Boniface’s apparent claim to temporal power was to propose a General Council to depose him. John implicitly supported this. Gratian had said that a pope cannot be judged ‘unless he is found straying from the faith,’ i.e. had become a heretic. To heresy commentators had added other serious sins (Tierney, 1980: 124-5). John adds age, illness, insanity, use-lessness and abuse of Church property as justifying deposition (1971: 101, 241). But with Boniface heresy was the main issue. John asks, what if a pope were to introduce a ‘new teaching’ without proper discussion among the learned or a general council; for example, what if the pope were to teach the heresy that it is heresy to deny that the king of France is subject in temporals to the pope? John answers that, if possible, papal teaching should be given a traditional, orthodox meaning, but if the pope insists on a new and injurious meaning and the Church is in danger, then the prince should resist by force and the Church should move to depose the heretic pope (1971: 231-4). ‘The prince is permitted to withstand the abuse of the spiritual sword as best he may, even by the use of the material sword’ (1971: 212). In deposing a pope the Church can be represented by the College of Cardinals, though a General Council would be better (1971: 241-3, 250).

On Royal and Papal Power contains a section that lists and then refutes arguments for the temporal supremacy of the pope. John’s list is very comprehensive, but we will look only at his discussion of some arguments used by Giles of Rome and Thomas Aquinas. One of Giles’s recurrent themes is the superiority of the spiritual over the corporeal (1971: 133). John replies that it is not true that the royal power is corporeal and not spiritual and is in charge of bodies and not souls; its end is life according to virtue. Also, it is not true that every spiritual function as such has authority over every corporeal function as such: in a household the tutor does not appoint the physician, but both are appointed by the head of the household (1971: 182-3). Another of Giles’s arguments was drawn from Augustine’s City of God, to the effect that there cannot be a true republic except among Christians (1971: 135). John replies that natural moral virtue, including justice, can exist without supernatural faith, and that this is enough for true government, which is concerned with the good life so far as it can be lived by natural human power.

John’s disagreement with Thomas Aquinas is of particular interest. Many passages in John’s book are taken almost verbatim from Thomas Aquinas, and John has been regarded as a follower of Thomas. Yet he mounts an effective criticism against the argument Thomas used in De regno to support papal lordship over temporals, namely the argument from the subordination of ends—that ‘those to whom pertains the care of intermediate ends should be subject to him to whom pertains the care of the ultimate end’ (compare Thomas Aquinas, 1978: 62, with John of Paris, 1971: 134). John offers a number of points in reply. The higher art uses the lower only in relation to its own end. It does guide, but not always with authority: in a household the physician guides the pharmacist but cannot give authoritative directions or dismiss the pharmacist, since they are both under the authority of the householder, and similarly both pope and prince derive their authority from God. The lower art may have something good or desirable in itself and indeed life in accordance with naturally acquired virtue is something good in itself. Finally, the lower end may be related to the higher in more than one way (e.g. a tyrant’s oppression may also lead people to God), so the higher art cannot uniquely direct the lower (1971: 184-6; the subordination of arts is discussed in several other places, 1971: 93, 182, 201).

Marsilius of Padua

Marsilius wrote his Defensor pacis (1324) to counter a cause of strife that Aristotle had not included in his discussion of revolutions (Politics, V) because it arose long after his time, namely a ‘certain perverted opinion’ among Christians (Marsilius of Padua, 1980: 5). Marsilius is in no hurry to tell us what that revolutionary opinion is, but eventually it transpires that it is the doctrine that the pope has fullness of power (1980: 361-2). An explicit attack on this doctrine occupies II.xxiii-xxvi, after the ground has been well prepared. All coercive power comes from the people (the ‘legislator’) and is entrusted to a ruler who rules in accordance with the law established by the people or by a subordinate legislator authorized by the people (1980: 44-9, 61-3). No community can have more than one supreme ruler, who must be the source of all coercive power in the community—otherwise strife will break out (1980: 80-6). This is the first of the four main points of Marsilius’s argument against papal fullness of power: unless the pope is the supreme ruler, pope and clergy can have coercive power only if they derive it from the supreme ruler. The second point is theological: that Christ excluded the clergy from the exercise of coercive rulership (1980: 113-40). This rules out the possibility that the pope or any cleric might be the supreme ruler. The third main point is also theological, a rejection of the view of Isidore and most churchmen, that the ruler must punish sin. According to Marsilius God wills that divine law should be enforced by sanctions only in the next world to give every opportunity for repentance (1980: 164; the contrast between ‘this world’ and ‘the next world’ was later the basis of Locke’s main argument in his Letter of Toleration). Marsilius does not advocate toleration: for secular ends the secular ruler may enforce religious uniformity, that is, he may enforce the divine law, but not the divine law as such (1980: 136, 175-9). So there is only one supreme ruler, not a member of the clergy, who does not enforce divine law as such and therefore does not coerce in any sense on behalf of the clergy. Fourth, Christ gave Peter no special authority among the apostles, and Peter never was in Rome (1980: 44-9). The Roman bishop therefore has no special Christ-appointed role in shepherding the whole Church. From these four points it follows that the doctrine of papal fullness of power is false in all its senses; in particular, the claim that the pope has supreme coercive jurisdiction over all secular rulers is false, for the pope and the clergy have no coercive jurisdiction at all, direct or indirect. As for ownership of property, Marsilius sides with the Franciscans against Pope John XXII’s thesis that no one can use consumable property without ownership, and argues that, in accordance with Christ’s will, the pope and the clergy should all live in poverty like the Franciscans (1980: 183-4, 196-215; see Tierney, 1997: 108-18). On his view, then, the clergy should have no lordship at all, either in the sense of coercive jurisdiction or in the sense of ownership of property. In the management of the externals of Church life, Marsilius argues that the only source of coercive authority is the secular ruler (if he is a Christian), who decides how many churches and clergy there will be, distributes Church jurisdictions, makes or approves appointments, and enforces canon law (1980: 65-6, 254-67), and only he can authorize excommunication (1980: 147-52). The only sources of doctrinal authority in the Church are the Bible and general councils: he argues that general councils are infallible (1980: 274-9). (William of Ockham, 1995: 207-19, opposed Marsilius on this point, and argued that no part of the Church is infallible; see also Kilcullen, 1991.) However, only the ruler can assemble a council, and its decisions can be enforced only by the secular ruler (1980: 287-98).

Marsilius does not deny the truth of Christianity, does not deny that Christ gave spiritual powers to the clergy (their ‘essential’ or ‘inseparable’ powers, in contrast to the ‘non-essential’; 1980: 235-6, 239-40), and does not deny that the clergy are the expert judges and teachers of Christian doctrine. What he denies is that Christ gave the clergy any coercive power and that Christ gave the pope any special power not possessed by other priests. Marsilius does not advocate the separation of Church and state, but (once the people have become Christians) something more like subordination of Church to state; more exactly, he maintains that coercion in Church life is then exclusively the business of the secular ruler. Marsilius gives different accounts of the relationship between Christian communities and secular government before and after the conversion of the peoples (1980: 256-9, 263-4). Before conversion the Church managed the externals of Church life autonomously, but afterwards its affairs are regulated by ‘the faithful human legislator which lacks a superior’ or by the ruler authorized by the legislator (1980: 272-3). After conversion the community and the Church are one, the ‘legislator’ has become ‘the faithful legislator’ and the ruler authorized by the faithful legislator has become the source of all enforcement within the Church.

William of Ockham

Ockham (see McGrade, 1974; Knysh, 1996) disagreed with Marsilius at many points, though he seems to have taken over from him the idea that the doctrine of fullness of power (or a certain version of it) was the root of much of the trouble in the Church. Ockham’s earliest political writing was the Work of Ninety Days (c. 1332), in which he defends the Franciscan theory of voluntary poverty as a religious ideal against Pope John XXII’s thesis that no one can justly consume without owning (William of Ockham, 2001). Part I of his Dialogus (c. 1334) discusses heresy and heretics, suggesting that to show that someone is a heretic it is not enough to show that what that person believes is heresy; it is necessary also to show that he or she believes it ‘pertinaciously,’ and to show this it is necessary to enter into discussion to discover whether the person is ready to abandon the error when it is shown to be such. On the other hand, a pope who tries to impose a false doctrine on others is known to be pertinacious precisely from the fact that he is trying to impose false doctrine on others, and a pope who becomes a heretic automatically ceases to be pope. Thus ordinary Christians (or a pope arguing as a theologian and not purporting to exercise papal authority) can argue for a heresy in discussion as long as they make no attempt to impose it on others, whereas a pope who tries to impose a heresy ceases to be pope and loses all authority. This is an argument for freedom of discussion within the Church, though not for toleration in general (see McGrade, 1974: 47-77; McGrade, Kilcullen and Kempshall, 2001: 484-95).

In his Contra benedictum (c. 1335) Ockham began his preoccupation with the Marsilian theme of fullness of power, which he continued in other works written in the later part of his life. Ockham rejects two versions of the doctrine of fullness of power. He denies that the pope has power from Christ to do whatever is not contrary to divine or natural law: against this he argues that a pope must respect not only rights and liberties under natural law, but also rights and liberties existing under human law, including those conferred on rulers by the law of nations and the civil law and custom, and that he must refrain from imposing excessive burdens (1992: 23-4, 51-8). He also rejects a weaker version of the doctrine of fullness of power, according to which the pope has all power necessary to secure the good government of the Christian people. Against this he maintains that securing good government in temporal matters is the concern of the laity, not of the clergy (1974: 70-1). However, there is some sense in which Ockham agrees that the pope has fullness of power: in spiritual matters (i.e. matters relating to eternal salvation and peculiar to the Christian religion) that are of necessity (not just useful), the pope regularly has full authority over believers (not unbelievers); in temporal matters he regularly has no authority, but on occasion, in a situation of necessity, the pope may do, even in temporal matters, whatever is necessary if it is not being done by whoever is normally responsible to do it (1992: 62-3; Kilcullen, 1999: 313-14). (Note the distinction between what is regularly or ordinarily true and what is true on occasion or extraordinarily: see Bayley, 1949.)

If Marsilius was the first exponent of the doctrine, later held by many others, notably Hobbes, that in any well-ordered community there must be a single locus of coercive power, Ockham was its first opponent. Ockham argues, as Locke would argue later, that if the community were subjected to one supreme judge in every case, then the supreme judge could do wrong with impunity. To prevent tyranny, it must on occasion be possible for the regularly supreme judge to be coerced by others. At the same time, it does no harm if there are some (for example pope and clergy, or cities or princes) who are regularly exempt from the jurisdiction of the supreme judge provided they can be coerced on occasion, and it does no harm if there are some who have coercive power that they have not received from the supreme judge—again, provided they can be coerced when they do wrong. To prevent tyranny some plurality of centres of power is needed, and how exactly those centres relate to one another does not matter, provided no one can do wrong with impunity. On various occasions, each of pope and prince may become subject to one another ‘by reason of wrongdoing,’ and in this way the pope might even become subject to the jurisdiction of a non-Christian emperor. An emperor coercing a pope for temporal wrongdoing would be exercising his ordinary power, whereas a pope coercing an emperor for temporal wrongdoing would be acting extraordinarily (William of Ockham, 1995: 310-31).

In his political writings Ockham makes much use of the theory of natural law, which originated in ancient philosophy and had been taken up again by medieval theologians and lawyers. The essential idea of the theory, as Thomas Aquinas and Ockham hold it, is that the human mind, reflecting on and analysing human experience, can ‘see’ the truth of various fundamental moral norms, which are thus ‘self-evident,’ not in need of proof, and too fundamental to be capable of proof (Thomas Aquinas, Summa, 1-2, q. 91, a. 3, and q. 94, a. 2). Ockham distinguishes several kinds of natural law (1995: 286-93), including natural laws ‘on supposition’: supposing certain contingent facts, natural reason sees intuitively that certain kinds of action are on that supposition morally right or wrong. Given the consequences of Original Sin, human communities have a natural right to establish institutions of government and property; given the establishment of those institutions, individuals have a natural right to acquire property (or to live without property, relying on the generosity of those who have property); given that some thing has become some person’s property, others have a natural duty not to use the thing without that person’s permission; and so on. The Christian community’s right to depose a heretic pope and choose a replacement is, for Ockham, such a natural right, in the same category as the right of any ‘people’ to depose a tyrant and establish a just regime. ‘Natural’ rights belong to human beings as such, to pagans as well as to Christians; thus the powers of the pope and clergy are limited by lay rights that pre-exist Christianity (1992: 51-8; not only natural rights but also rights under human positive law limit the pope’s power).

There has been a tendency in Christian thought to say that after Adam’s fall into sin, the human mind is too depraved to be capable of genuine moral insight; indeed, that since the Fall no human being can do anything but sin and can have no rights, without God’s special grace. Ockham, Thomas Aquinas and the medieval Church strongly rejected this opinion and attributed to ‘fallen’ human nature, even apart from grace, the ability to distinguish right from wrong, to possess rights, and to direct human action to ends that are legitimate (though without grace it is impossible to attain the very highest end of ‘beatitude’). This optimistic view of the moral capacities of even unregenerate nature is at the root of Ockham’s contention that non-Christians are capable of genuine ‘lordship’ in both senses, i.e. of governmental power and of property rights. Later theologians inspired by this conception of natural rights defended the property and governmental rights of the natives of America against European aggressors, some of whom argued that unregenerate savages could have no rights (see Muldoon, 1966; 1980). Luther and Calvin, despite their emphasis on the corruption of human nature by Original Sin, and despite their maxims sola scriptura and sola fide, still found a place for natural law (see McNeill, 1946). Hooker continued this natural law tradition, arguing (as Ockham and the conciliarists had done) that natural reason can be a source of principles even in regard to Church polity (see Kirby, 1999).

Natural law was, of course, a leading political idea in the seventeenth and eighteenth centuries. Hobbes’s egoism was a radical departure, but Locke was clearly in the medieval tradition. Hume’s ‘invented’ natural laws were close to Ockham’s natural laws ‘on supposition.’ (On the continuity of the tradition see Buckle, 1991. For references to laws of nature being ‘invented,’ see Hume, 1975: 520, 543.) There continued into the eighteenth century a common conception, derived from medieval writers, of natural reason, i.e. reason unaided by Christian revelation, as a source of fundamental ethical principles. According to Bayle, the natural light of reason must guide interpretation of revelation itself: if God seems to have commanded in the Bible anything clearly contrary to natural morality, then we must have misunderstood his command (1708: 43-57, Part 1, ch. 1).


On the central question of the relationship between spiritual and temporal power, Thomas Aquinas endorsed papal claims to supremacy, Giles maintained that all legitimate power on earth belongs primarily to the pope, and Marsilius that all legitimate coercive power belongs to the secular ruler. John of Paris argued for a restriction of the spiritual power to spiritual methods of action, and of the temporal power to temporal methods of action, but allowed each to use its appropriate methods to achieve indirectly some effects in the other’s sphere. William of Ockham argued that the pope has fullness of power in spiritual matters and may on occasion intervene in temporal affairs, but only in situations of necessity when the laity will not or cannot act. James of Viterbo argued a position like that of Giles (see Dyson, 1995); so did Augustine of Ancona (see McGrade, Kilcullen and Kempshall, 2001: 418-83). John Wyclif continued Giles’s argument that lordship cannot belong to unbelievers, or, as Wyclif argued, to anyone in sin (2001: 587-654). Several short works akin to John of Paris, On Royal and Papal Power, were produced at about the same time (see Dyson, 1999a; 1999b; on the circumstances of these writings see Saenger, 1981). There were other contributors to the debate whose works are not available in English (for these see Miethke, 2000a). No medieval writer, as far as I know, argued that secular power should as a matter of principle not be used to benefit true religion and discourage religious error. To my knowledge the first persuasive argument for such a degree of separation of the two powers was Bayle’s in thePhilosophical Commentary.

It may seem remarkable that such active and free-ranging debate should have taken place during the middle ages on such a central topic of religious belief as the role of the religious head. Why did not piety and faith repress discussion and demand unquestioned deference to God’s representative on earth? The theologians who debated the power of the pope sometimes felt called on to justify debating the topic; both John of Paris (1971: 229-35) and William of Ockham (1992: 5-12) offered justifications, but so did one of the strongest advocates of papal power, Augustine of Ancona (William of Ockham, 1992: 6, n. 10). Justification was easy enough, because it was already the established tradition in the medieval universities to allow, indeed encourage and require, students and academics to debate both sides of every question from the existence of God and the creation of the universe to the details of grammar. Even heretical opinions were supposed to be presented in university debate, though they were not supposed to win. Ockham also did not want heresy to win: in fact his ‘political writings’ are a campaign against papal heresy. But his discussion of ‘heresy and heretics,’ making the point that one can maintain a heretical opinion without being a heretic as long as one remains open to correction and does not try to impose one’s opinion on others, made it easier to argue freely.

Medieval academic debate was more formal than we are accustomed to, and the conventions required that a teacher state and explicitly answer a fair number of arguments, as strong as possible, for the thesis the teacher wanted to reject. This formal dialectical style is exemplified by most medieval writings on political theory. The literature of Christianity, for example the works of Augustine, already embodied a tradition of theological questioning, a continuation of the philosophical and literary culture of the ancient world. In the medieval universities this was strongly reinforced by the study of logic and the practice of formal dialectical discussion, and by the example and precept of Aristotle:

For those who wish to get clear of difficulties it is advantageous to discuss the difficulties well; for… it is not possible to untie a knot of which one does not know… Hence one should have surveyed all the difficulties beforehand… Further, he who has heard all the contending arguments, as if they were the parties to a case, must be in a better position to judge. (Metaphysics, III.1, 995 a23-b5)

Aristotle here follows Plato and Socrates. The medieval universities handed down to modern times the Socratic tradition of free discussion of important and sensitive topics. Although political theory was not an ordinary subject of instruction, the involvement of university people in writing on political questions for a university-educated readership carried into politics the academic practice of free argument on both sides of fundamental questions.