The importance of doubting
The active cultivation of doubt, a Socratic legacy, is the path to wisdom
“There is freedom of thought, and each one can sustain what he wants, as for me, I will stick to my principle, and I will always seek in every question the maximum probability, without being bound by the law of any particular school to which shall forcibly follow my speculation.” (Cicero, Tusculan Disputations, IV.4.7)
Sometimes one of my students, perhaps a bit frustrated at the inability to defend their position on a subject under discussion, will say: “Well, everyone is entitled to their opinion.” Yes and no, I reply. In the world at large this may be true. Unfortunately, everyone feels entitled to their opinions, and even more unfortunately they don’t hesitate to broadcast it as far as their social media account will carry. But in a philosophy class, or in reasoned discourse in general, people are entitled to their opinions only to the extent they can defend such opinions on the basis of evidence and argument.
This is something that our media could benefit from learning. The notion that, whenever there are two positions on a given issue we need to listen to both, to allow “equal time” no matter how nonsensical or harmful an opinion may be is nonsense on stilts.
But how do we balance the values of freedom of thought and respect for truth? By actively cultivating an attitude of doubt, like the Roman advocate, statesman, and philosopher Marcus Tullius Cicero did throughout his life.
Cicero was philosophically eclectic, and we’ll discuss in a minute what exactly that means. He attended both the Stoa and the Academy, and philosophers like Diodorus, Philo, Antiochus, and Posidonius regularly stopped by his house for a chat. Diodorus of Tyre was allegedly an Aristotelian, but according to Cicero actually espoused a philosophy that struck a compromise between Stoicism and Epicureanism (the greatest good is a combination of virtue and absence of pain). Philo of Larissa was a head of the Academy during its skeptic period. Antiochus of Ascalon was a pupil of Philo who tried to reconcile Stoicism, Aristotelianism, and Platonism. And Posidonius was one of the middle Stoics, who however diverged in several respects from orthodox Stoicism.
With such a diverse philosophical diet, you can immediately see why Cicero might have been drawn to eclecticism. He considered himself to be an Academic, and thus an intellectual descendent of both Socrates and Plato, but he saw no major differences between Stoicism, Aristotelianism, and Platonism. And yet Alexandre Skvirsky  puts forth a convincing argument that Cicero’s philosophy was not only original with respect to the big three just mentioned, but even with respect to the sort of Academic Skepticism that was practiced in Athens by the likes of Arcesilaus and Carneades.
To appreciate the difference, and—more importantly—to get a sense of why Cicero’s original philosophy is so relevant to us denizens of the 21st century, we need to talk a bit more about that pesky word, “eclecticism.”
When I looked it up in my dictionary, the first entry says: “deriving ideas, style, or taste from a broad and diverse range of sources.” The second entry was more specifically philosophical in tone: “denoting or belonging to a class of ancient philosophers who did not belong to or found any recognized school of thought but selected doctrines from various schools of thought.”
Figs in Winter: New Stoicism and beyond is a reader-supported publication. To receive new posts and support my work, consider becoming a free or paid subscriber.
The problem is that most, if not all, philosophical schools are eclectic in the sense that they derive their ideas from a variety of sources, combining them in novel ways and adding their own contributions. Consider Stoicism, for instance. We tend to think of it as a well defined school, but its founder, Zeno of Citium, studied with an array of teachers for many years before trying his own hand at teaching in the famous Stoa Poikile. As a result, Stoicism includes identifiable contributions from Socrates, Platonism, Aristotelianism, and the dialecticians associated with the Megarian school. It is true that Chrysippus of soli, the third head of the Stoa, cleaned things up a bit and made the Stoic system more coherent, but it is also true that plenty of unorthodox Stoics—such as the above mentioned Posidonius—kept teaching their own idiosyncratic version for centuries thereafter.
So being inspired by different sources isn’t really what distinguishes an eclectic from a standard school of philosophy. Besides, Cicero did think of himself as belonging to a particular school, what we today call Academic Skepticism. But he conceived of his chosen philosophy in a novel and very practical way.
When we think of pragmatic Greco-Roman philosophies we tend to think of Stoicism, with its tradition of spiritual exercises aimed at ethical self-improvement. And yet, as my colleague John Sellars has recently pointed out to me, early Stoics like Chrysippus were little inclined toward practice and much more into theory and logic. It is only with the Roman Stoics (Epictetus, Seneca, Marcus Aurelius) that Stoicism developed the distinctly pragmatic approach that it retains to this day.
And Cicero—as a good Roman—was nothing if not pragmatic. Here is a revealing comment to that effect he made about a colleague in the Senate, Cato the Younger (a Stoic!), who in Cicero’s judgment let his rigid principles get in the way of obtaining results:
“As for our friend Cato, you do not love him more than I do: but after all, with the very best intentions and the most absolute honesty, he sometimes does harm to the Republic. He speaks and votes as though he were in the Republic of Plato, not in the scum of Romulus.” (Cicero, Letters to Atticus, II.1.8)
Cicero’s approach to skepticism can be characterized as a form of “eclectic probabilism,” meaning that he thought it wise to help himself to whatever notion appeared to him more probable (he actually invented the word probabilis), regardless of which philosopher originally articulated it. Moreover, because he was convinced that human reason is fallible and that we cannot achieve ultimate truths, probability is the best we can do. A consequence of this position is that one has the freedom, and the intellectual obligation, to change one’s mind if the evidence points in a new direction. As he put it:
“Our position is not that we hold that nothing is true, but that we assert that all true sensations are associated with false ones so closely resembling them that they contain no infallible mark to guide our judgement and assent. From this followed the corollary, that many sensations are probable, that is, though not amounting to a full perception they are yet possessed of a certain distinctness and clearness, and so can serve to direct the conduct of the wise person.” (De Natura Deorum, I.5.12)
In other words (and, again, contra the Stoics), there is no sure mark of Truth (notice the capital T), not because there is no such thing as true or false statements, but because our human epistemic limitations (fallible reason, fallible senses) do not allow us to be absolutely sure that we can tell the difference in every case. But this does not, and should not, stop us from assessing situations and making decisions about courses of action, so long as we keep in mind that our assessment and decisions could turn out to be incorrect and may need to be revised.
Now, one can take this recognition of human epistemic limits as a bummer. Or one can realize that it is actually liberating. If we embrace doubt we are thereby free from having to stick with rigid doctrines. We can (indeed, we ought to!) change our mind whenever the pertinent arguments or evidence point in a new direction. No more endless stubborn fights to defend an opinion that has become part of our personal identity. We can instead go wherever reason leads us.
But how do we figure out what is and is not probable? Cicero tackles the issue directly:
“One cannot have a clear vision of what is probable, unless a comparison of the arguments of both sides is made.” (De Officiis, II.2.8)
Here he builds on the Skeptic tradition of engaging in an exercise of thorough and honest defense of alternative positions, as if they were our own. That way we put ourselves in a better place to evaluate contrasting ideas than the standard situation where we pick one hypothesis—the one that makes intuitively most sense to us—and then inevitably develop a tendency to defend it because it is “our.”
There is good evidence from modern pedagogy that the technique actually works. When teachers assign students at random to defend one or another position in a debate—say, on abortion, or transgender issues—the students develop a deeper understanding and respect for the side to which they are assigned, regardless of whether they initially agreed or not with that side.
However, here is where Cicero’s philosophy diverges significantly from that of previous skeptics, and where it becomes far more useful to us. In ancient Skepticism—both Pyrrhonism and Greek Academic Skepticism—the idea was to create a situation of equipollence, where two contrasting notions where thoroughly examined and defended in order to create an epistemic equivalency between them.
For instance, when Carneades—then head of the Academy—visited Rome on a diplomatic mission in 155 BCE he gave two lectures on justice on consecutive days. In the course of one lecture he defended the notion that justice is of paramount importance and a matter of virtue. In the other he articulated the opposite viewpoint, that “justice” is what winners impose through their might. Spectators couldn’t tell Carneades’ own opinion, which was on purpose. The goal of equipollence was understood to be that the inquirer would be led to suspend judgment (epoche, in Greek) on the matter at hand. In turn this suspension of judgment would lead to ataraxia, or tranquillity of mind, which is the true goal of life. 
By contrast, when Cicero argues both sides of a given question his goal is to establish which—if any—is more probable. He is after the best available approximation to the truth, not suspension of judgment. Indeed, he thinks that suspending judgment is just not a viable option when it comes to important matters like virtue and justice. If the result of our inquiries is equipollence that just means that we haven’t reached—yet—a threshold that allows us to reasonably judge one hypothesis as significantly more probable than another. Again, the proper reaction is not suspension of judgment, but a renewed inquiry. And the ultimate goal is not tranquillity of mind, but truth and virtue.
A clear advantage of the active cultivation of doubt intrinsic in Cicero’s eclectic probabilism is that it leads to epistemic humility. As he puts it:
“As well as other schools maintain that some things are certain, others uncertain, we, deviating from them, say that some things are likely, some improbable. What, therefore, prevents me from accepting what seems to me probable, and rejecting what seems to me improbable, and this way running away, avoiding the presumption of clear affirmations, to rashness, which is very far from wisdom?” (De Officiis, II.2.7-8)
This is the sort of refreshing attitude that I wish to cultivate myself, and that I think would go a long way to help modern scientists and science popularizers, who could use a bit of epistemic humility. That may have put them in a better position to communicate things effectively during the Covid pandemic, for instance.
Probabilistic skepticism a la Cicero, then, positions itself between dogmatism on the one hand and total doubt on the other hand, and it is a more constructive attitude than either. The ability to doubt is at the root of freedom (to change one’s mind), humility, and the (probabilistic) search for truth. As Cicero points out, this is ultimately a Socratic lesson:
“Socrates doubts all things.” (Academica, I.17)
With the possible, partial, exception of Carneades, who in fact inspired Cicero, this is a novel position in Greco-Roman thought, and Cicero deserves more credit as an original philosopher than he is usually given. As Skvirsky points out in his paper, “One does not find in the works of Plato, Aristotle, or Sextus Empiricus a philosophical use of the various Greek words that express the concept of doubt (such as distazo, endoiazo, diakrino).”
And we in the 21st century would do well to encourage—in ourselves as well as in others—the use of words that express constructive doubt. It is the path to wisdom.
 Alexandre Skvirsky, “Doubt and dogmatism in Cicero’s Academica,” Archai 27, e02705.
 Though the equipollence > epoche > ataraxia sequence is usually attributed to Pyrrhonian Skepticism, the Academic Skepticism of Arcesilaus (who was, in fact, a student of Pyrrho) is for all effective purposes hard to distinguish from Pyrrhonism. Carneades may have later on moderated the Academic position and began a turn toward the sort of probabilism that was then fully developed by Cicero.