Scholars are divided on the worth of Cicero's political thought, as it is contained in his On Duties, The Laws and The Republic. Readers of Plato will recognize the titles of the last two, which Cicero purposefully emulated along with their literary styles to try and appropriate Greek philosophy and prose for Latin consumption. Philosophy in Latin had scarcely been attempted before, and some see Cicero's achievement mainly as making Greek philosophy fit for Roman consumption.
Cicero is certainly an excellent prose stylist, an extremely laudable achievement given he was also hugely successful in the spheres of politics and the civil law. Nor should his political ideas be seen merely as adapations of Greek traditions to justify the Roman constitution and placate Romans hostile to philosophy, especially foreign philosophy. His On Duties remained a handbook for statesman and all those interested in public affairs for over one thousand and five hundred years after it was written, and Erasmus had a pocket-sized edition commissioned so that one could carry it everywhere.
More difficult to assess is the quality of his Republic and Laws, as only fragments of them remain. The Republic was in extremely poor shape until a Vatican manuscript was discovered in 1820, but we still do not have anything near the full six-book work. The Laws is especially battered, and only the sections concerning religious rites and the magistrates remain. Parts of the works can be inferred from the comments of others, especially Augustine of Hippo in De Civitae Dei, but they are still largely incomplete. However, we have enough to see that Cicero did go beyond the Greeks in some respects, and that he has produced works that deserve their own place in the history of political thought.
The necessity of political action
The virtues are absolutely central to Cicero's political thought. In On Duties he explicitly names the four virtues he considers to be the most important, and they are wisdom (the search for knowledge), social virtue (justice and liberality), greatness of spirit (courage) and seemliness or moderation. In Cicero's Republic we are told that 'the existence of virtue depends entirely on its use; and its noblest use is the government of the state', which suggests that virtue can only be realized through political action. On Duties provides a detailed guide as to how the statesman should employ the virtues in public life.
However, slightly later in Republic, we are told that it is a sense of duty and necessity that makes a philosopher leave the life of contemplation and engage in politics. If the polity is not preserved, then he will not have the opportunity to engage in contemplation anyway. So although virtue can exist outside of the polity in the form of a search for wisdom, its main necessary sphere of action is within it. In On Duties it is made clear that participation in public life for those capable is a result of possession of greatness of spirit, as to not discharge this duty is indicative of a fear of the failure and hardship it could bring. The social virtue, comprising of justice and liberality, only has a meaning in relation to other men. Virtue then is necessarily shown within the polity, but this does not by itself mean it is central to political action in Cicero's view. It is the theory of natural law which Cicero expounds in Laws, Republic and On Duties which puts virtue at the very centre of his political thought.
To Cicero, natural law is the idea that there are timeless and innate laws of nature to which it is just for all human societies to conform. Human beings share in their reasoning capability with God, and 'those who share reason also share right reason; and since that is law, we men must also be thought as partners with the gods in law' (L. I 22). As all men share in the reasoning capacity, they will all discern the same abstract laws of nature if they set their minds to contemplating them, as these laws are inherent in nature itself. The basic law of nature as defined in Book III of On Duties is that it is never right to harm another for your own advantage, as this destroys the common fellowship of humanity which consists in their shared reasoning capacity.
By stooping to the level of a beast and employing force an individual repudiates this connection and tarnishes his soul (which has the effect of making him a just target for robbery or murder himself, which is Cicero's defence of tyrannicde). Civil laws should derive from this natural law as much as possible, and when they fail to do so they are not even to be considered laws. Political communities which implement laws which closely approximate the laws of nature will be more permeable as they will be more just, and the people within will have less cause to overthrow the constitution. The virtues that man exercises are hence the predilection towards action which is in conformity with the laws of nature.
It is theoretically possible to imagine the search for knowledge being carried out in the absence of a political community. However, Cicero is adamant that the best use for wisdom is in seeking political knowledge about how best political communities should be formed and run. His interlocutors in Laws and Republic frequently state that they can think of no better use for their free time than to meditate on such issues, which is a judicious use of their leisure time because it is of benefit to the state. Cicero approximates Aristotle's argument that people form political communities due to an innate desire which is part of their nature, and the type of man who is most praised is the one who combines a search for wisdom with political action, so long as in so doing he exercises the other virtues as well.
Someone who has great knowledge but acts contrary to justice will be regarded not as wise but a crafty trickster. The best use for wisdom is in shaping the laws of a political community to be as much as possible in accordance with the laws of nature, something which is not achievable for every state at every time but is optimal. The job of the wise man is to approximate the laws of nature as much as possible. Hence, the virtue of wisdom has a special case in Cicero's political thought, as it advises on what action is to be taken at what time. When combined with practical experience, philosophy and wisdom make the best of statesman: the history of Rome furnishes only a few examples, as Cicero notes with melancholy.
Greatness of spirit is likewise central to Cicero's political thought. Courage is necessary to encourage people to engage in political life rather than preferring a life of pleasure and idleness with their family. Both military and civic office come with hardships and sacrifices, and a doctrine that enshrines pleasure as its goal would be afraid of taking on responsibilities because of the hardships and possible failures it would involve. Courage is hence to be praised as long as it is exercised in accordance with the other virtues, especially justice. Courage which was divorced from justice would be bestial and savage, and would violate the rule of nature that no-one should rob another for their own benefit.
Cicero's discussion of the virtue of greatness of spirit focuses on the duties owed to society which courage allows one to discharge without fear. Without courageous people who are willing to make sacrifices for the good of the community in civic matters the constitution would not receive the hard work it needed to endure as the Roman constitution as described in Republic had. Similarly, without people willing to make sacrifices on military campaigns the state would be overwhelmed by its outside enemies. Greatness of spirit is hence also central to Cicero's political thought, as an abstract appreciation of honour (measured by deeds and not glory) is necessary to make men sacrifice themselves for the good of the community.
The role of the 'most illustrious virtue', justice, has already been seen in the two virtues already discussed: it is fully appreciated through wisdom, and it guides greatness of spirit in what action to take. As a virtue of its own, justice is the most central to political life of all of Cicero's virtues. A political community’s laws must be constituted as closely as possible to the natural law which is derived from natural justice, which is shared by gods and men. In this way the political community will be as permeable as possible. In Republic, Cicero favours the mixed constitution as the best way to organize states, but also declares monarchy to be the best of the simple forms of government. This is because rule by one excellent man who has a high reasoning capacity allows the laws to be crafted in accordance with natural justice as much as is possible; unfortunately, this form of government is all too prone to lapse into tyranny when an unsuitable monarch assumes power.
The best constitution is hence the one which most closely approximates natural justice, which can be discerned by the wise. Cicero prescribes that all individuals who are involved in the political life of the state should also exercise the social virtues to a large extent, being liberal with money and services where it is appropriate and where it will bind the polity together. The good of the community is always the highest good to be aimed for (even philosophers leave their lives of contemplation when duty calls), and beneficence towards the individual is only a virtue when it does not harm the community.
Conclusion: against hedonism
The exercise of justice is, then, the cardinal virtue for Cicero. To not harm another for your own benefit and to always keep faith are fundamental laws of nature which must be observed so that an individual's immortal soul is not tarnished and so that the community of mankind remains bound together. The bonds of society, a collection of rational human beings, are broken when individuals within descend to the level of beasts by acting unjustly and contrary to nature. As societies are natural institutions, they must obey these laws by practicing the virtues.
Wisdom and greatness of spirit are ancillary to natural justice, the human approximation of which is the foremost of virtues in a political community. There remains to be discussed the virtue of moderation and its opposite, hedonism, which Cicero leaves to the very end of On Duties. For hedonism in the inverse and perversion of all of the virtues discussed so far. It reduces reason to the mere role of searching for the most pleasurable actions, and wisdom to the level of knowledge of pleasure.
A hedonist is hence seen as a more intelligent beast, seeking pleasure just like animals and not exercising wisdom in a search for knowledge like gods. This means he will not pursue political knowledge, which is necessary to constitute and run political communities. Furthermore, pleasure blunts courage and will discourage service to the state. Lastly, if the virtues are pursued just for the pleasure they bring, then they are rendered meaningless and the natural fellowship of the human race is destroyed. Hedonism is hence the greatest vice of humanity, and by seeking it all other virtues are destroyed, as would be all political communities.