Developments in Medieval Political Theory

Politically themed writing by Christians in the second and third centuries tended to be apologetic in nature, defending the church as neither subversive nor perverse. Yet Christians also thought of themselves a separate way of life, a politeia, alternately opposing or permeating the old order. In 313 when Constantine issued the Edict of Milan and made Christianity legal within the Roman Empire, things were bound to change, and after 324, Christianity quickly became the established religion. This was a watershed event, but not one that produced complete consensus:

1. Some, such as Eusebius of Caesarea, saw the imperial approval of the faith as the natural outcome of the expanding Christian mission, while others, such as Ambrose of Milan, continued to hold that the Christian witness was in the way of martyrdom and that all political authority must be called to account by the church's message.
2. A shift in the Christian view of military service did take place between the third and fourth centuries. Whereas before, it had been common to see military service as either unacceptable or at least suspect for Christians, it became more acceptable. In part, this was despite baptismal vows against it, perhaps because it was a time when Christians often delayed baptism to later in life.
3. Already the political experience of Christians in different parts of the empire was leading to differing views of church and state. The Latin experience with Roman republican tradition led to a view of the church and state as separate entities, while the Greek experience of imperial rule led to a monist position often labeled (perhaps unfairly) as "caesaropapism."
4. The Greek Patristics were more likely to stress the connection between the logos as a pattern of rationality inherent in the universe and nomos as the law that establishes that pattern. This led in the fourth and fifth centuries to a greater hope that the imperial ruler might be an instrument of God's providence. The Western tradition was just as likely to stress what Augustine would call the two cities: "the City of God" and "the City of Man." Augustine himself argued for the need for rulers to act as a just restraint on human sinfulness, while the church's role was to offer mercy and penitence to the remorseful.

The Early Medieval era can be divided into three broad periods with characteristic, if intertwining emphases:

1. Late Antiquity: Christians, such as SIdonius Apollinarius and Cassiodorus, stressed portraits of the new rulers as "citizen-emperors" and as rulers bound by law, promulgating an idealized vision of humble, missionary kings. At the same time, the Roman pontiff came to be understood more and more as a separate power from and a spiritual authority over that of kings. New legal codes arose, most importantly that under Justinian. The Justinian Code included such important concepts as the difference between written and unwritten law, the relationships of law to rights, and the concept of the emperor being accountable to the law because his sovereignty is conferred by the people.
2. The Post-Justinian Period:  Pope Gregory I and Isidore of Seville developed the notion of public authority as a ministry within the purposes of God. The authority of ecclesiastical leadership and regal kingships are each chosen by God to suppress and correct evildoing in the populace, and their exalted status and power is given by God with this office in mind. Isidore also stressed that natural, divine law is ascendant over and more permanent than human, customary law, and he further developed theories of rights as deriving from nature, civil establishment, and national action.
3. The Carolingian Empire: The forged document, the Donation of Constantine, possibly written during the reign of Pope Stephen II, helped to establish papal control of the territory surrounding Rome. Pope Leo III's crowning of Charlemagne in 800 as "Emperor of the Romans" gave new life to the notion of a new Roman empire as a Christian political order. In theory, Charlemagne reigned as a king-priest (rex et sacerdos) who guarded the legal, political, and spiritual health of his people. In practice, Frankish kings were equally dependent upon legal compacts with the aristocratic sections of the populace. The Council of Paris in 829 attempted to stress again the division of political and spiritual powers, proclaiming the right of the bishops to speak on matters of the Church, and adjuring the political rulers to make just laws, punish wrongdoing, and maintain a good social order. 

1. Papal Corruption: The period between the late 9^th century and mid-11^th century suffered from extensive papal corruption with a succession of murders, power plays, and the children of popes being placed on the papal throne. Popes were often appointed as puppet rulers by powerful Roman barons. The period ended in 1046 with Henry III interfering in order to depose three rival popes. In 1059, the Papal Election Decree established a college of cardinals to choose successive pontificates.
2. The Lay Investiture Controversy: After the mid-11th century the Roman Catholic Church and the Western rulers, especially those associated with the Holy Roman Empire and the Capetian dynasties, were in constant tension, each set on a course of political expansion. The Lay Investiture Controversy embodied the various rival theories of papal and royal authority (1075-1122), beginning in a showdown between Pope Gregory VII (Hildebrand) and Henry IV of the Holy Roman Empire and climaxing in Pope Urban II's continued opposition to Henry IV and Henry V. Gregory VII willing used the power of excommunication to force Henry IV to give up the practice of electing bishops, abbots, and priests, as well as to (unwilling) acknowledge the superior authority of the pope, as did Urban II against the less strong-willed Henry V. The Corcordat of Worms in 1122 recognized the right of the emperor to have symbolical territorial jurisdiction in church matters, but also stressed the separate authority of the papacy to make its own ecclesiastical appointments.
3. Expanding Papal Power: Papal reasoning extended the “power of the keys” beyond the assumed powers of excommunication, penance, and purgatory to wide-spread ecclesiastical control of all the subordinate offices of the Roman Church. Papal supremacy now extended to judging bishops, electing church officials, granting plenary indulgences, as well as claiming immunity from royal judgment. A letter of the Patristic Leo I's was used to stress the doctrine of papal plenitudo potestatis (fullness of power), holding that papal authority and dignity included both temporal and spiritual power. The "two swords" doctrine came to mean that the pope possessed both swords, but had granted the temporal sword to rulers; therefore, the papacy had the right to depose kings and emperors. The papacy came to be understood as a "corporation of corporations" which included the executive administration and ownership of otherwise semi-independent organizations (monasteries, hospitals, parishes, etc.) that held church property and assets.
4. Imperial Reassertion: Understandably, royal and imperial prerogatives were asserted in answer to this. Dynastic counter-pressure was mustered to maintain the two swords as separate bodies and separate authorities. However, Henrys IV and V, Frederick I, as well as his Hohenstaufen descendants, did not attempt to entirely reassert imperial control over the ecclesiastical appointment process. Philip IV (the Fair) of France came closest to this until Frederick II put forth his Liber augustalis, a revival of the theory that the king serves as the high priestly protector of public justice, proclaiming himself "God's vicar on earth."
5. Law and the Common Good: Others, such as Henry Bracton and John of Salisbury held that royal power was bound by human and divine law. Kings should voluntarily imitate Christ in their service to their people, as well as in his submission to Father God. Salisbury, in particular, stressed the difference between a true king who serves the law and the common good and a tyrant, who is entirely self-serving, as well as the right of people to overthrow tyrants who abuse the common good. With the influx of Aristotelian and Thomist natural law theory, medieval political theory took a more nuanced reading of both civil and ecclesiastical power and authority. In particular, Aquinas looked at how the civil community could address "natural moral dignity" and the need for a common will to pursue the common good of the people, including in that the pursuit of virtue and charity. Post-Aquinas theory embraced a more extreme separation of the goals and purposes of royal and papal rule, as well as a more radical stress on the rights and powers of political corporations.

1. Captivity and Schism: The Babylonian Captivity (1309-1377), or the seven popes of the Avignon papacy, represent one of the nadirs of papal authority and influence, and the Great Papal Schism (1378-1417) that followed represents the almost intolerable state things eventually descended to, with two rival lines of popes in Avignon and in Rome, and after the Council of Pisa, three competing claimants. The Council of Constance (1414) eventually resolved the issue, but also raised the larger question of the power relationship of church councils and popes, an issue not entirely decided in the papacy's favor until the dissolution of the Council of Basel (1431-1449). Constance's policy was to see the authority of Christ's revealed in both pope and council, while Basel went further, treating the pope for a season as the minister of the conciliar corporation.
2. Marsilius of Padua was one of three important late medieval theorists. He argued for the spiritual poverty of the church, one without political jurisdiction or wealth. The civil ruler should work to establish civic harmony, and the people represent the true source of the best laws and the ultimate authority of the ruler. The best forms of government are ones that clearly establish the responsibility of the ruler to the people. Marsilus supported a definition of the church as "the whole body of the faithful" and the work of the councils as divinely inspired. His work was eventually placed on the Papal Index (1559).
3. John Wyclif, the second theorist, also stressed spiritual poverty as an ideal for the church to attain. He held to the authority of scripture as an inerrant and sufficient guide for life and law, and he put his words where he mouth was, in promoting translations of scripture into the vernacular of the people. Wyclif held that the "evangelical lordship" of the Christian community freely possess the goods of the creation without claiming proprietary ownership, while "civil lordship" is a fallen necessity in a world dominated by private interest and limited resources. Civil lordship is at its best when it practices a just use of property for the needs of the poor. Wyclif held the monarch to have a plenitude of rule by God's design in order to benefit the church and the people. 
4. William of Occam, third of the great theorists, held that the right of property proceeded any regal attempt to grant or define it, that the common use of property is Adamic in origin, and that the voluntary forsaking of all property is commanded by Christ for spiritual perfection. He held that theologians trained in scripture are more qualified to bring correction to doctrine than the compulsory force of popes, and he argued that church councils are not automatically inspired since they are men trying to understand the meaning of scripture. Papal authority is a divine grant, though meditated by fallible humans, while imperial authority is only given by the consent of the people.

This overview is deeply indebted to Oliver O'Donovan and Joan Lockwood O'Donovan's monumental study, From Irenaeus to Grotius: A Sourcebook in Christian Political Thought. Grand Rapids: Eerdmans, 1999.