When Christianity became the predominant creed of the empire under Constantine (converted 312) and the sole official religion under Theodosius (379–395), political philosophy changed profoundly. St. Augustine’s City of God (413–426/427), written when the empire was under attack by Germanic tribes, sums up and defines a new division between church and state and a conflict between “matter” and “spirit” resulting from original sin and the Fall of Man from the Garden of Eden.

St. Augustine, whose Confessiones (397) is a record of a new sort of introspection, combined a Classical and Hebraic dualism. From the Stoics and Virgil he inherited an austere sense of duty, from Plato and the Neoplatonists a contempt for the illusions of appetite, and from the Pauline and patristic interpretation of Christianity a sense of the conflict between Light and Darkness that reflects Zoroastrian and Manichaean doctrines emanating from Iran. In this context worldly interests and government itself are dwarfed by the importance of attaining salvation and of escaping from an astrologically determined fate and from the demons who embody the darkness. Life becomes illuminated for the elect minority by the prospect of eternal salvation or, for those without grace, shrivels under the glare of eternal fires.

St. Augustine regarded salvation as predestinate and the cosmic process as designed to “gather” an elect to fill the places of the fallen angels and so “preserve and perhaps augment the number of the heavenly inhabitants.” The role of government and indeed of society itself becomes subordinated to a “secular arm,” part of an earthly city, as opposed to the “City of God.” The function of government is to keep order in a world intrinsically evil.

Since Christianity had long played the main role in defense of the veneer of a precarious urban civilization in antiquity, this claim is not surprising. Constantine was a soldier putting to rights a breakdown in government, which nevertheless would continue in the West until the abdication of the last Western emperor in 476, though in the East the empire would carry on with great wealth and power, centred on the new capital of Constantinople (see Byzantine Empire).

St. Augustine thus no longer assumed, as did Plato and Aristotle, that a harmonious and self-sufficient good life could be achieved within a properly organized city-state; he projected his political philosophy into a cosmic and lurid drama working out to a predestinate end. The normal interests and amenities of life became insignificant or disgusting, and the Christian church alone exercised a spiritual authority that could sanction government. This outlook, reinforced by other patristic literature, would long dominate medieval thought, for with the decline of civilization in the West the church became more completely the repository of learning and of the remnants of the old civilized life.

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The Social Contract and Philosophy

John of Salisbury

After Augustine, no full-length speculative work of political philosophy appeared in the West until the Policraticus (1159), by John of Salisbury. Based on John’s wide Classical reading, it centres on the ideal ruler, who represents a “public power.” John admired the Roman emperors Augustus and Trajan, and, in a still predominantly feudal world, his book carried on the Roman tradition of centralized authority, though without its Byzantine autocracy. The prince, he insists, is he who rules in accordance with law, while a tyrant is one who oppresses the people by irresponsible power. This distinction, which derives from the Greeks, Cicero, and St. Augustine, is fundamental to Western concepts of liberty and the trusteeship of power.

John did not know Aristotle’s Politics, but his learning is nevertheless remarkable, even if his political similes are unsophisticated. His favourite metaphor for the body politic is the human body: the place of the head is filled by the prince, who is subject only to God; the place of the heart is filled by the senate; the eyes, ears, and tongue are the judges, provincial governors, and soldiers; and the officials are the hands. The tax gatherers are the intestines and ought not to retain their accumulations too long, and the farmers and peasants are the feet. John also compares a commonwealth to a hive and even to a centipede. This vision of a centralized government, more appropriate to the memory of the Roman Empire than to a medieval monarchy, is a landmark of the 12th-century revival of speculative thought.

Aquinas

It is a far cry from this practical 12th-century treatise by a man of affairs to the elaborate justification of Christian kingship and natural law created by St. Thomas Aquinas in the 13th century, during the climax of medieval Western civilization. His political philosophy is only part of a metaphysical construction of Aristotelian range—for Aristotle had now been assimilated from Arabic sources and given a new Christian content, with the added universality of the Stoic and Augustinian world outlook. Aquinas’s Summa theologiae (1265/66–1273) purports to answer all the major questions of existence, including those of political philosophy. Like Aristotle, Aquinas thinks in terms of an ethical purpose. Natural law is discussed in the first part of the second book as part of the discussion of original sin and what would now be termed psychology, while war comes under the second part of the second book as an aspect of virtue and vice. Law is defined as “that which is regulation and measure.” It is designed to promote the “felicity and beatitude” that are the ends of human life. Aquinas agrees with Aristotle that “the city is the perfection of community” and that the purpose of public power should be to promote the common good. The only legitimate power is from the community, which is the sole medium of people’s well-being. In his De regimine principum (1266; On the Government of Princes), he compares society to a ship in need of a helmsman and repeats Aristotle’s definition of man as a social and political animal. Again following Aristotle, he considers oligarchy unjust and democracy evil. Rulers should aim to make the “life of the multitude good in accordance with the purpose of life which is heavenly happiness.” They should also create peace, conserve life, and preserve the state—a threefold responsibility.

Here is a complete program for a hierarchical society within a cosmic order. It combines the Hellenic sense of purpose with Christian aims and asserts that, under God, power resides in the community, embodied in the ruler but only for so long as the ruler does right. Hence the aphorism “St. Thomas Aquinas was the first Whig”—a pioneer of the theory of constitutional government. The society he envisages, however, is medieval, static, hierarchical, conservative, and based on limited agriculture and even more limited technology. Nonetheless, Thomism remains the most complete and lasting political doctrine of Roman Catholicism, since modified and adapted but not in principle superseded.

Dante

By the early 14th century the great European institutions, empire and papacy, were breaking down through mutual conflict and the emergence of national realms. But this conflict gave rise to the most complete political theory of universal and secular empire formulated in the medieval West, by the Italian poet and philosopher Dante Alighieri. In De monarchia (c. 1313), still in principle highly relevant, Dante insists that only through universal peace can human faculties come to their full compass. But only “temporal monarchy” can achieve this: “a unique princedom extending over all persons in time.” The aim of civilization is to actualize human potentialities and to achieve that “fullness of life which comes from the fulfillment of our being.”

Monarchy, Dante argues, is necessary as a means to this end. The imperial authority of the Holy Roman emperor, moreover, comes directly from God and not through the pope. The empire is the direct heir of the Roman Empire, a legitimate authority, or Christ would not have chosen to be born under it. In subjecting the world to itself, the Roman Empire had contemplated the public good.

This high-flown argument, part of the political warfare between the partisans of the emperor and pope that was then affecting Italy, drives to essentials: that world peace can be secure only under a world authority. That Dante’s argument was impractical did not concern this medieval genius, who was writing more the epitaph than the prospectus of the Holy Roman Empire; he was concerned, like Aquinas, to create a political philosophy with a clear-cut aim and a universal view.

Out of the grand but impractical visions of the High Middle Ages in the 13th-century climax of Christian civilization, there emerged by early-modern times the idea of a well-governed realm, its authority derived from the community itself, with a program designed to ensure the solvency and administrative efficiency of a secular state. In spite of the decline of the civilization of antiquity in the West, the Greco-Roman sense of purpose, of the rule of law, and of the responsibility of power survived in Christian form.

Machiavelli

In the thought of the Italian political philosopher Niccolò Machiavelli may be seen a complete secularization of political philosophy. Machiavelli was an experienced diplomat and administrator, and, since he stated flatly how the power struggle was conducted in Renaissance Italy, he won a shocking reputation. He was not, however, without idealism about the old Roman republic, and he admired the independent spirit of the German and Swiss cities. This idealism made him all the more disgusted with Italian politics, of which he makes a disillusioned and objective analysis. Writing in retirement after political disgrace, Machiavelli states firmly that,

since this is to be asserted in general of men, that they are ungrateful, fickle, false, cowards, covetous, and as long as you succeed they are yours entirely: they will offer you their blood, property, life, and children…when the need is far distant; but when it approaches they turn against you.

And again,

since the desires of men are insatiable, nature prompting them to desire all things and fortune permitting them to enjoy but few, there results a constant discontent in their minds, and a loathing of what they possess.

This view of human nature, already expressed by Plato and St. Augustine, is here unredeemed by Plato’s doctrine of Forms or by St. Augustine’s dogma of salvation through grace. Machiavelli accepts the facts and advises the ruler to act accordingly. The prince, he states, must combine the strength of the lion with the cunning of the fox: he must always be vigilant, ruthless, and prompt, striking down or neutralizing his adversaries without warning. And when he does an injury, it must be total. For “men ought to be either well treated or crushed, because they can avenge themselves of lighter injuries, of more serious ones they cannot.” Moreover, “irresolute princes who follow a neutral path are generally ruined.” He advises that it is best to come down at the right moment on the winning side and that conquered cities ought to be either governed directly by the tyrant himself residing there or destroyed. Furthermore, princes, unlike private men, need not keep faith: since politics reflects the law of the jungle, the state is a law unto itself, and normal moral rules do not apply to it.

Machiavelli had stated with unblinking realism how, in fact, tyrants behave, and, far from criticizing their conduct or distinguishing between the just prince who rules by law and the tyrant whose laws are in his own breast, he considers that the successful ruler has to be beyond morality, since the safety and expansion of the state are the supreme objective. In this myopic view, the cosmic visions of Aquinas and Dante are disregarded, and politics becomes a fight for survival. Within his terms of reference, Machiavelli made a convincing case, although as an experienced diplomat he might have realized that dependability in fact pays and that systematic deceit, treachery, and violence usually bring about their own nemesis.