The Ancient Roman Cicero’s idea of natural law has much to teach us about the evolution of liberty

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Paul Meany
Intellectual History Editor

Paul Meany is the Editor for Intellectual History at Lib​er​tar​i​an​ism​.org, a project of the Cato Institute. Most of his work focuses on examining thinkers who predate classical liberalism but still articulate broadly liberal attitudes and principles. He is the host of Portraits of Liberty, a podcast about uncovering and exploring underrated figures throughout history who have argued for a freer world. His writing covers a broad range of topics, including proto‐​feminist writers, Classical Greece and Rome’s influence on the American Founding, ancient Chinese Philosophy, tyrannicide, and the first argument for basic income.

Cicero is a rarity in history: a philosophically inclined man who held political power. He was born in Arpinum in 106 BC. His political career took place during the twilight of the ailing Roman Republic. He was a self‐​described constitutionalist, but also a dedicated moderate who wished for peace and harmony above all else. Cicero’s natural law views persist as influential to this day. Unlike many of his contemporaries, Cicero did not forge a career by means of war but instead through oratory in the law courts of his day. He opposed the tyranny of Caesar and, subsequently, Mark Antony. Eventually, Cicero was assassinated after delivering an intensely scathing condemnation of the tyranny of Mark Antony as part of a series of speeches entitled the Philippics.


Studying Cicero offers us key insights into both the development of modern western theories of natural law and the structuring of political communities around these principles. Given Cicero’s massive influence, it is a shame that the praise bestowed upon him has drastically waned in the last hundred years. But it is never too late for a revival; Cicero’s work proves consistently useful and relevant, especially considering its wide‐​reaching repercussions on western intellectual and political history.

God, the Divine Mind of the Universe

Cicero was a skeptic of the religious beliefs of his day. As a politician in a state in which religious institutions played a prominent role, Cicero respected the Roman religion, though solely on the grounds of tradition and utility. At certain points in his writing he chastised people for taking the traditional religious myths too seriously. On the topic of poetical works and the people who take them literally he wrote that “they are demanding in this case the kind of truth expected of a witness rather than a poet.” 1 Cicero knew that there was a difference between historical and poetic truths. Cicero therefore did not take as literal the descriptions of the Roman pagan gods.

But this is not to say that Cicero was an atheist. To the contrary, since he was influenced by contemporary Stoics, Cicero believed that there was a divine reason which governed every aspect of the universe; “I say, then, that the universe and all its parts both received their first order from divine providence, and are at all times administered by it.” 2 In the last chapter of his De Re Publica , Cicero described how all people are granted their souls by the eternal fires of the stars and planets under God’s control.

For Cicero, this divine mind designed and ordered the universe. He asserted that all things are implanted with a function and end towards which they are directed by the dictates of their own nature; this is called law. To Cicero, “law in the proper sense is right reason in harmony with nature.” 3 These laws are not in constant flux or evolution. Cicero stated emphatically that “there will not be one such law in Rome and another in Athens, one now and another in the future, but all peoples at all times will be embraced by a single and eternal unchangeable law.” 4

Since everything is designed with an end or purpose in mind, Cicero believed that by examining and understanding something’s form and function, one could figure out how something ought to act. Thus he argued that by examining humanity he could understand how humanity ought to act. To comprehend the nature of justice, one must seek it by understanding the nature of humanity, since “moral excellence is nothing other than the completion and perfection of nature.” 5

A Dash of Divinity in Each Person

Cicero firmly believed that humanity stood between God and the beasts, “for whereas nature made other animals stoop down to feed, she made man alone erect, encouraging him to gaze at the heavens as being, so to speak akin to him and his original home.” 6 The favored status accorded to humanity is affirmed by our possession of the interrelated faculties of reason and speech.

Reason allows us to perform four main functions. Firstly, it enables us to infer causal relationships between external objects. We do not just see that dominos fall, but rather we understand that they fall as part of a chain of events. Secondly, reason equips us to remember events, thus allowing us to accumulate knowledge and increase our understanding of the world throughout our life. Thirdly, our capacity for reason allows us to moderate our behavior; unlike animals who are slaves to their passions, humans can act civilly around others and be considerate. Lastly, and most importantly from Cicero’s perspective, is humanity’s quest for truth: “above all, the search after truth and its eager pursuit are peculiar to man.” 7 We have the urge to uncover the divine order of the universe in all fields of life, whether it be through logic, astrology, mathematics or philosophy.

Our other divine faculty is speech, which Cicero called “the queen of arts.” 8 Speech is a critical ability because it enables people to cooperate, work towards common goals and compromise on issues. Cicero insisted that, rather than using brute force like beasts, we are instead capable of utilizing rational discourse to achieve our ends: “There two types of conflict: the one proceeds by debate, the other by force. Since the former is the proper concern of a man, but the latter of beasts, one should only resort to the latter if one may not employ the former.” 9 We also use speech to gain knowledge and share it with our fellow people. Speech in combination with memory, as facilitated by reason, allows people to learn more than animals could ever comprehend. However, speech is not only a tool, but a sign of humanity’s sociable nature. We are not designed to live alone, “for our species is not made up of solitary individuals or lonely wanderers.” 10 Speech is a distinctive quality of man that allows for cooperation. As Cicero concluded, speech “has separated us from savagery and barbarism.” 11

Universality of Humanity

Every person in possession of these faculties is considered a member of the worldwide commonwealth of humanity. Each human is endowed with two personas. The “second persona” is individual to every person. It is composed of our talents, our personal tastes and our respective duties assigned to us based upon our individual abilities. The “first persona,” which is common to all people, incorporates our capacity for speech and reason. Cicero believed that reason is the highest good, for “what is there, I will not say in man, but in the whole of heaven and earth, more divine than reason?” 12 The importance of reason is emphasized because it is present both in humanity and in God. Therefore, “there is a primordial partnership in reason between man and God” which makes humanity special and distinguishes man from other living beings. 13 This partnership is not limited to a certain sect of humanity, but to all who resemble Cicero’s definition of man: the endowment of a soul with speech and reason. “[T]hus however one defines man, the same definition applies to us all. This is sufficient proof that there is no essential difference within mankind.” 14 Cicero further affirmed the universality of humanity, stating that all races can attain virtue by using nature as their guide. An important consequence of this partnership between God and humans is that every person is infused with a dash of divinity, meaning both that they are worthy of dignity and that they command our respect until proven otherwise.

As mentioned before, divine law implants everything in the universe with an end goal, or a purpose for existing. Cicero believed that humanity’s ultimate goal was justice. Stressing this point, he exclaimed that “surely nothing is more vital than the clear realization that we are born for justice.” 15 For Cicero, justice was not only a useful tool for creating harmony among men, but was also a virtue in and of itself. All that is good, according to Cicero, necessarily contains a degree of justice, “for nothing can be honorable if justice is absent.” 16 Justice elevates all things to a more respectable plain, since “justice is the crowning glory of all virtues.” 17

To Cicero, natural law was not merely a theory of individual moral conduct; instead, it provided a blueprint for society. Natural law played a crucial role in shaping Cicero’s political philosophy, most notably in two key areas; Cicero’s normative definition of law and his defense of private property.


Cicero insisted that civil law must shape itself in accordance with the natural law of divine reason. To him, justice was not a matter of opinion, but of fact. He believed that law “is spread through the whole human community, unchanging and eternal, calling people to their duty by its commands and deterring them from wrongdoing by its prohibitions.” 18 If the law of men (civil law) does not conform with the commands of nature (divine law), Cicero argued that by definition, the former cannot be truly considered law, as true law is “right reason in harmony with nature.” 19 Since we derive justice from humanity’s nature and man’s relationship to his environment, anything contrary to this cannot be considered just or lawful. Cicero concluded that the principles of justice are fourfold: (1) do not initiate violence without good reason; (2) keep one’s promises; (3) respect people’s private property and common property; (4) be charitable to others within one’s means. 20

According to Cicero, the state exists to uphold laws which are in harmony with the universal principles of nature. If a state does not uphold right reason in agreement with nature, it is not a state. The law and the state are normative in nature, rather than conventional. He argued that without the key element of justice embodied in law, a state cannot be formed, observing that “many harmful and pernicious measures are passed in human communities–measures which come no closer to the name of laws than if a gang of criminals agreed to make some rules.” 21 In his speeches condemning Mark Antony, Cicero even suggested that the laws Mark Antony passed held no validity as he enforced them using naked violence, rather than right reason. For Cicero law is more than just force, it is right reason in agreement with nature. 22 Similarly, on the subject of Caesar, Cicero believed the emperor’s reign was a state in form but not in ethical substance. 23

Private Property

Cicero’s philosophy is characterized by a strong sense of individualism. This is most evident in his approach to private property. Agreeing with the Stoics, Cicero believed that God gave the world to man for his own use: “everything produced on the earth is created for the use of mankind.” 24 However this does not mean that we share everything in common, for Cicero argued that every creature has a tendency to preserve itself, but the difference between human and beast lies within man’s capacity to plan for the future. Thus, private property is important and necessary as it allows people to live in peace. Every person is expected to appropriate for themselves and their family what they need to survive. Cicero held that one of the reasons people united in the state of nature was in order to preserve what was already in their possession.

For Cicero, property has always existed, even in the state of nature, i.e., in the absence of a governmental body. Cicero did not claim that ownership of property is a natural right, but rather believed that it was established through a mixture of convention and consent. Even though property is not a natural right, it is a logical extension of our nature. One of the main features of Cicero’s natural law theory is the concept of “to each his due.” 25 If the state is authentic in its conduct (i.e. adhering to the principles of natural law), then it will formalize and protect what each person has legitimately appropriated from nature.

Many ancient Greek thinkers had previously discussed why people congregated in political communities. Aristotle’s description of humanity as a “political animal” was commonplace throughout ancient thought. However, Cicero was one of the first thinkers to posit the view that the preservation of property rights was one of the core reasons people formed states. On the duties of public officials Cicero wrote that “the men who administer public affairs must first of all see that everyone holds on to what is his, and that private men are never deprived of their goods by public acts.” 26

One can justly acquire property through due process of the law, long occupancy, purchase, and conquest through just war. 27 Cicero’s stance on private property conforms to his principles of justice: “of justice, the first office is that no man should harm another unless he has been provoked by injustice; the next that one should treat common goods as common and private ones as one’s own.” 28 Unlike Plato and Aristotle, Cicero did not believe that the highest function of the state was the molding of people’s characters; instead, he asserted that it was to safeguard people’s life and liberty.

While Cicero condemned excessive greed and lust, he generally believed that people should be allowed to accumulate wealth so long as they do not harm others in their ventures. Quoting the Stoic Chrysippus, Cicero made the comparison between the accumulation of wealth and a race; there is no issue with putting all your effort into winning the race, provided one does not trip others along the way. The theme of “leaving people alone, as long as they do not harm others” is a recurring idea in Cicero’s thought.

Cicero’s Lasting Influence

Cicero’s views have had enormous impact on the development of western thought. It is therefore a tragedy that he has become increasingly overlooked in recent times. The marginalization of Cicero is in part a consequence of accusations that his work consists solely of restated views of Greek philosophers. The originality of Cicero’s work is a difficult topic to discuss as many of the sources he would have “copied” are lost to the ravages of time. However, it is certain that his writings are the first surviving works of political philosophy that discuss extensively the fundamental concept of natural law and the way in which society could be organized on the basis of its principles.

Admirers of Cicero throughout history have been in no short supply. The Roman biographer Plutarch tells the story of the emperor Augustus walking through his home. While Augustus, an enemy of Cicero, is strolling he finds his grandchild attempting to hide the fact that he was reading Cicero. When Augustus saw the book, he took it and then gave it back, telling his grandson that its author was “a learned man, my child, a learned man and a lover of his country.” 29

During the medieval period, the ethical handbook De Officiis was one of the most widely read texts in Europe, next to the Bible. Throughout the Renaissance, Cicero was widely praised amongst the Italian republics for his skill as an orator and for his just conduct as a statesman. He was praised by Petrarch, the father of humanism, as “the great genius” of antiquity. 30

In early modern England, John Locke employed Cicero’s phrase “salus populi suprema lex,” or “let the welfare of the people be the ultimate law,” as an epigraph to his most famous work, The Second Treatise On Government. Locke even went so far to say that “‘salus populi suprema lex’ is certainly so just and fundamental a rule, that he, who sincerely follows it, cannot dangerously err.” 31

During the American Revolution, Founding Father John Adams wrote in reference to Cicero that ‘all the ages of the world have not produced a greater statesman and philosopher united in the same character, his authority should have great weight.” 32 When fellow Founding Father Thomas Jefferson was drafting the Declaration of Independence, he cited what he called “the elementary books of public right.” Among these were the works of Cicero. 33 Jefferson referred to Cicero as both an “exalted patriot” and “the father of eloquence and philosophy.” 34

Arguably, the influence of Cicero rivals that of philosophical heavyweights Aristotle and Plato. For anyone interested in the evolution of liberty from the natural rights‐​based tradition of politics, Cicero is undoubtedly an invaluable resource.

1. Cicero, De Legibus, 1.4.

2. Cicero, De Natura Deorum, 2.30.

3. Cicero, De Re Publica, 3.32.

4. Cicero, De Re Publica, 3.33.

5. Cicero, De Legibus, 1.26.

6. Cicero, De Legibus, 1.27.

7. Cicero, De Officiis, 1.13.

8. Cicero, De Natura Deorum, 2.148.

9. Cicero, De Officiis, 1.34.

10. Cicero, De Re Publica, 1.39.

11. Cicero, De Natura Deorum, 2.148.

12. Cicero, De Legibus, 1.22.

13. Cicero, De Legibus, 1.23.

14. Cicero, De Legibus, 1.30.

15. Cicero, De Legibus, 1.28.

16. Cicero, De Officiis, 1.62–63.

17. Cicero, De Officiis, 1.20.

18. Cicero, De Re Publica, 3.33.

19. Cicero, De Re Publica, 3.33.

20. Neal Wood, Cicero’s Social and Political Thought (Berkeley, 1991), p. 77.

21. Cicero, De Legibus, 2.13.

22. Cicero, De Re Publica, 3.22.

23. Cicero, De Officiis, 1.26, 3.32, 3.82–85.

24. Cicero, De Officiis, 1.22.

25. Cicero, De Officiis, 1.15, 20, 23.

26. Cicero, De Officiis, 2.73.

27. For more information on Cicero’s theory of just war consult Gavin Stewarts chapter on Cicero in Just War Thinkers: From Cicero to the 21st Century (London, 2017).

28. Cicero, De Officiis, 1.20.

29. Plutarch, Cicero, 49.3.

30. Petrarch, On His Own Ignorance, 40.

31. John Locke, An Essay Concerning the True Original, Extent, and End of Civil Government, XIII:158.

32. John Adams, A Defence of the Constitutions of Government of the United States of America, I:xix-xx, xxi.

33. Jeremy Bailey, Thomas Jefferson and Executive Power (Cambridge, 2007), p.106.

34. The Jefferson Cyclopedia (New York, 1900), p. 142, 818.