Ancient Skepticism’s 7 Philosophers

What are the roots of ancient skepticism? Learn about three periods that involve the most influential skeptical thinkers.

Jul 26, 2023By Antonio Panovski, BA Philosophy

ancient scepticism period explained


In the Hellenistic period of philosophy, three very notable schools of thought emerged: Epicureanism, Stoicism, and Skepticism. They each came up with their own metaphysics, epistemology, and ethics. However, skepticism remained completely silent on all these subjects but still contributed greatly to philosophy. Doubting everything, skepticism held a neutral position in every aspect of possible knowledge. But, how did skepticism start? Who were the first skeptics? And how did their theories develop further? Let’s take a look at ancient skepticism’s roots, and examine the three periods of ancient skepticism through their most prominent thinkers.


1. The Early Period of Skepticism—The Forming of Ancient Skepticism

Pyrrho of Elis (c. 360—c. 270 BCE), founder of Skepticism, via Wikimedia Commons.


a.) Pyrrho (365-275) 


Pyrrho wrote nothing of his own. It is through Timon and Diogenes Laertius, a biographer of Greek philosophy, that we learn about his skepticism and philosophy. His philosophy is partly a response to the philosophy of the Sophists, the Eleatics, and the Megarians’ dialectic. According to Laertius in his Lives and Opinions of Eminent Philosophers, Pyrrho taught that:


Nothing is beautiful nor ugly, nor just and unjust, and the attitude that nothing is true is equally valid for everything, and everything that people do is based on assumptions and habits because nothing is what it seems like, but is different than that.


From this theoretical point of view arises the practical:

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If there is something that would be good or bad in itself, then it should be so for everyone, just as the snow is cold for everyone. But there is no such thing that would be good or bad for everyone, therefore there is nothing that is good or bad in itself


The objects of our cognition and knowledge are unavailable and inaccessible, says Pyrrho. That’s why we should refrain from giving any judgment. Refraining from passing judgment should be a daily practice so that we might avoid disappointment.


Refraining from making judgments is also necessary because it brings us peace of mind, that is, inner tranquility—ataraxia. Without ataraxia, one cannot achieve complete satisfaction and happiness.


b.) Timon (320-230) 


Timon studied under the mentorship of Stilpo in Megara, before going to Elea and starting his new philosophical mentorship under Pyrrho. He wrote a big book in which he makes a parody of the teachings of Homer and Hesiod in the form of satire, as well as ridiculing all the dogmatic schools (except Xenophanes, who he appreciated greatly).


Timon was the one that presented the teachings of the old period most systematically and efficiently. He summarized what Pyrrho taught about, and showed his own philosophy as well. He said:


He who wants to be happy must be careful about these three things: first, what things are, secondly, how we should behave towards them, and finally, what results from such behavior of ours.


He says about things that they are unsolvable, immeasurable, and inestimable; therefore, our perception and even our opinion should not be considered true or false. Therefore, we should never believe anything and refrain from passing any judgment, because:


it also exists as much as it does not exist, or it neither exists nor does not exist.”


Thus, Timon concludes that not believing in the things around us is the only way we can achieve ataraxia.


2. Middle Period—Thinkers from Academic Skepticism

Arcesilaus and Carneades, skeptics from the new Academy, via Wikimedia Commons.


a.) Arcesilaus (315-240) 


Arcesilaus was greatly influenced by Pyrrho and Timon. He was the first Academic to adopt a position of philosophical skepticism. He used skepticism as a weapon against the dogmatism of the Stoics and the epistemological weaknesses of other schools. It is the skeptical elements in the philosophy of Socrates and Plato that enabled Arcesilaus’s skepticism to enter the Academy.


Arcesilaus disputes the teaching of the Stoic Zeno. He rejects his teaching about the measure of truth that the Stoics located in the cataleptic representation, i.e., a representation which, because of its completeness and clarity, is undoubtedly true. Arcesilaus said that every representation is variable and unstable.


He further restores and renews the teachings of Pyrrho. Pyrrho insisted that we should distance ourselves from all theory and limit and focus on practical life, and we should refrain from passing any judgment. From this position of Pyrrho, Arcesilaus rejected the standards of truth. However, he did not reject them completely, as Pyrrho did. Instead, he points to a reasonable measurement that will serve as a norm for practical action. The standard of reasonable measurement and judgment, he says, is sufficient to distinguish what we ought and ought not to do, and are good enough to attain spiritual tranquility and ataraxia.


Marble head of Carneades from Cyrene, founder of the new Academy and the most important of the Academic skeptics, via Wikimedia Commons.


b.) Carneades (129-214) 


Carneades is considered to be the official founder of the new Academy. Along with Diogenes from Babylon, Carneades opened up the first philosophical courses in Rome, which were mostly visited by the youth of Rome. He does not seem to have ever written any texts. However, we find out about his teaching through his students and followers.


Carneades opposed the philosophy of Epicurus, the philosophy of Arcesilaus, as well as the philosophy of the Stoics, especially that of Chrysippus. He himself even says: “If there was no Chrysippus, there would be no me either.


Following Arcesilaus’ critique of Stoic standards of truth, Carneades rejects their views as well. However, he goes even further. He also rejects Arcesilaus’ idea of the standard of reasonable measurement, saying that all things are changeable and, as such, the senses, representations, and reason deceive us all. Thus, he concludes that there is no such thing as a “standard of truth.”


Being strongly opposed to Stoic philosophy, Carneades rebels against all the different theories and doctrines that the Stoics held. However, his rebellion is most noticeable against the deterministic nature of their teachings. The Stoics’ determinism leads to fatalism—a belief that all events are predetermined and, therefore, inevitable. Carneades strongly disagrees with this position.


Destiny (Le Destin) from Jazz by Henri Matisse, 1947, via MoMA.


Carneades says that there is no such thing as certain knowledge and that such knowledge is impossible. That’s why he defines, and therefore limits, all knowledge simply as probable. That’s how he came up with his most significant concept yet—the three layers (degrees) of probability. The first layer is where the probable representations about knowledge are located—so clear that they do not leave any reason for doubt. Within the second layer are representations of knowledge that are both probable and unquestionable. Finally, the third layer contains the representations of knowledge that are probable, unquestionable, and verified. This is the stage where we can certainly believe that the knowledge we have gotten to know is true.


His skepticism also extends to the field of ethics. It challenges the notions of law, justice, fairness, and morality. Law and justice have conditional and relative value, he says. They are determined by people guided by their interests. The same applies, says Carneades, to the concepts of good and evil. There is no such thing as absolute good and absolute evil. If a thing is good or bad, it should be like that for everyone, but there is no such thing. Thus, Carneades allows the probability of knowledge and truth in the field of ethics as well as a criterion of determining what’s good and what’s evil, what is right and what is wrong.


3. Late Period—The End of Ancient Skepticism

Sextus Empiricus, the most notable thinker of late skepticism, via British Museum


a.) Aenesidemus (80-10 BCE) 


Aenesidemus was discontented with the views discussed in the Academy at his time, and he aimed to revive a more radical skepticism and left the Academy for this purpose. Arguably, he is the first Pyrrhonian skeptic. His most significant work is Pyrrhonian Discourses. Indeed, he is famous for having developed Ten Modes or Tropes that are contained in the treatise. The Ten Tropes are actually forms of argument by which the skeptic puts appearances and thoughts into opposition. The subjects of investigation in each of the Tropes are the things that are changeable.


Here, we’re going to mention just a few of the arguments. For example, the second argument says that different people have different constitutions, so they probably experience the world differently and want different things because they experience them differently. The fifth argument says that things look different to us depending on the distance and the perspective. For example, a coin seen obliquely looks ellipsoidal; seen at a right angle, it looks round; and from a distance, a ship appears to be small. The seventh argument says that things look different to us depending on the quantity and the arrangement. For example, in small quantities, wine strengthens people, while in large quantities, it weakens them; another example is that small pieces of silver appear black, while larger pieces appear white.


These few arguments that we mentioned clearly show the goal that Aenesidemus was striving for. What they all have in common is that they show how we cannot believe anything. That’s why we should refrain from giving any sort of judgment. This is the only way of achieving ataraxia.


b.) Agrippa (1st century CE)


Almost nothing is known about Agrippa. He is important because he introduces five more arguments as a follow-up to the arguments of Aenesidemus. His arguments show that we have no and cannot have reasons for believing in anything, and therefore we must refrain from all belief. Aenesidemus’ tropes derive from the relativity of perception, while Agrippa’s arguments are derived from the structure of the justification of belief. Later they are reduced to three arguments instead of five, and that’s how Agrippa’s trilemma was created.


c.) Sextus Empiricus (2nd century CE)


Sextus Empiricus and his philosophy are considered to be the culmination of not only the late period of Skepticism but of all of ancient Skepticism altogether. We know little or nothing about the life of Sextus Empiricus, including when and where he lived. We learn about him mostly from Diogenes Laërtius. When it comes to his philosophy, it’s his Outlines of Pyrrhonism that tell us about his philosophical stances. In it, Sextus outlines what it takes to be a Pyrrhonian skeptic—the possession of a certain skill, and what the pay-off for being a Skeptic is—tranquility. That, according to Sextus, is the end point of skepticism—reaching or achieving tranquility, i.e., ataraxia. It is through refraining from giving any sort of statement, judgment, or thought, that we can achieve ataraxia. He defines doubt as “a faculty which sets itself in opposition to what appears and to what is thought.” It is through refraining that we break free from confusion, disorder, and unrest, says Sextus Empiricus.


A physically impossible shape, the Penrose triangle, which can nevertheless be depicted and experienced. Via Unsplash.


Sextus Empiricus also explains how people become skeptics. Certain people are “troubled by the anomaly in things” and want to take away this “trouble,” i.e., become tranquil. So if we are smart and energetic, we seek intellectual tranquility because of the many contradictions the world seems to offer. More succinctly, Sextus says that tranquility follows the suspension of judgment “as a shadow follows a body.”


4. Conclusion: Ancient Skepticism’s Relationship to Other Hellenistic Philosophy

Epicurus (341–270 BCE), founder of Epicurean philosophy, via Wikimedia commons.


We can conclude that skepticism as a philosophical school from the Hellenistic period stands neutral in terms of traditional philosophical disputes. Epicureanism and Stoicism, as philosophical schools of the same period, make their own contribution to the traditional philosophy before them. They present their own views in the field of metaphysics, epistemology, logic, as well as ethics. On the other hand, skepticism remains completely neutral and silent on these issues. However, this does not mean that skepticism does not contribute to the philosophical richness.


Skepticism contributes greatly to the understanding of knowledge itself. It shows that there exists a certain fallacy in the process of human cognition, which is strongly important because it’s something we need to be aware of when acquiring knowledge about the world. This is also important because the contradictory nature of the world can cause distress and disappointment, as all skeptics note. This, in turn, prevents us from achieving complete bliss, i.e., ataraxia—the state of inner tranquility. Ataraxia is the highest value in Hellenistic philosophy as a whole. Epicureanism regarded it as the highest value as well. And, although the Stoics give primacy to apathy as a supreme value in their philosophy, they still refer on several occasions to the well-being in the state of mindlessness and inner tranquility—the state of ataraxia.

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By Antonio PanovskiBA PhilosophyAntonio holds a BA in Philosophy from SS. Cyril and Methodius University in Skopje, North Macedonia. His main areas of interest are contemporary, as well as analytic philosophy, with a special focus on the epistemological aspect of them, although he’s currently thoroughly examining the philosophy of science. Besides writing, he loves cinema, music, and traveling.