Natural Law is the “how” but not the “what” of ethics.
Cicero, although he probably appropriated Stoic rhetoric more than he sincerely embraced Stoic worldviews, authored a number of formulations which are taken as early versions of the Natural Law hypothesis. Cicero’s writings on this topic were influential on Roman thought.
Octavian, later known as Caesar Augustus, either cooperated in the assassination of Cicero, or at least did not block the murder. Yet even he was influenced by Natural Law thinking.
The Romans who lived during the decades of transition from the Roman Republic to the Roman Empire encountered complex ethical questions because of this transition, and Natural Law often entered into the public discussion of these questions.
To be sure, some public statements were more sincere than others, but even those who wrote or spoke cynically needed the logic of Natural Law to persuade their audiences.
As a method, Natural Law fit well into this situation, because Roman religion was increasingly nonfunctional: few took the pantheon of Roman polytheism literally or seriously. Although vague allusions to “the gods” or to one of the gods by name were standard ornamental phraseology in Latin and Greek rhetoric, these words could have as easily appealed to nature, common sense, or experience.
Even if, and to the extent that, one took the pagans gods seriously, they were of little help in addressing ethical dilemmas. These deities were capricious and arbitrary, often motivated by rage or jealousy, committing adultery, and betraying, fighting, punishing, waging war against, and killing each other.
The Stoics had no logical or systematic motivation to engage in the polytheistic system, but used occasional rhetorical mention of the gods and goddesses as cultural accommodations.
Stoicism contained within itself the germ of the logical rejection of polytheism, and the seed of a systematic monotheism, which in the thinking of some Stoics took the form of a pantheistic conception of the entire universe having its own agency, personhood, teleology, or consciousness.
But despite the Stoic inclination toward monotheism, Stoic ethics founded itself on a version of Natural Law which was based more on nature than on divine legislation. (A millennium or two later, this would emerge explicitly in the thought of writers like Grotius.)
Thus among pagans and Stoics, and among both sincere and insincere adherents of the two groups, the vocabulary of Natural Law - again, sometimes sincerely used, and sometimes not - formed a mutually intelligible basis for public discourse about ethical questions.
Consequently, among a wide range of Roman historical persons, Natural Law formulations are used to discuss moral propositions. Historian Korey Maas writes:
abortion was discouraged by Rome’s first Emperor, Caesar Augustus, and even punished by the similarly pagan emperors Septimus Severus and Antonius Caracalla. The Stoic philosopher Musonious Rufus, in particular, and the philosophical school of Stoicism more generally, objected to it. Some first-century physicians, interpreting the Hippocratic Oath as forbidding all abortions, refused to perform them. The satirist Juvenal could bluntly describe the abortionist as one “paid to murder mankind in the womb.” The Roman poet Ovid, not otherwise given to moralizing, could be so harsh as to declare that “Who unborn infants first to slay invented, Deserved thereby with death to be tormented.”
Despite this commendable evidence, all was not well with Natural Law discourse during the Roman Empire. The actions of the empire undermined the moral credibility of its society’s authors and speakers.
While Roman writers and orators contributed to the spread of Natural Law discourse, they also contributed to its emptiness. However sound or valid their argumentation may have been, they operated within a system which many in their audiences saw as baseless, or as based only on the lust of power.
Although Caesar Augustus had some moral impulses which the Roman public viewed as noble, some of his other actions were perceived as unnecessarily harsh. While his rule brought some relief from decades of civil war, his greed for power was undeniable.
Many thinking citizens saw the empire and its emperors as illegitimate, although it was dangerous to say so. In authors from Lucan to Tacitus, one detects hints that the moral illegitimacy of the empire spread like a disease, infecting other areas of life, including private life, with vanity, with vacuity, and with meaninglessness.
Because an amoral monster like Nero employed those who used both Stoic rhetoric and Natural Law discourse, such verbiage was seen as bankrupt. The willingness of audiences to take such vocabulary seriously was undermined.
Thus it was that during the Roman era, Natural Law discourse flourished for the first time, and during that same era declined.
