Carneades

Carneades
Region	Ancient Greek philosophy
Known for	Probabilistic skepticism; dialectical method opposing Stoic dogmatism
Movement	Skepticism
Occupation	Philosopher
School	New Academy (Academic Skepticism)
Era	Hellenistic philosophy
Position	Head (scholarch) of the New Academy
Wikidata	Q284994

Carneades (c. 214–129 BC) was a Greek philosopher who led the Platonic Academy (the “New Academy”) during its skeptical phase. He is best known for arguing that no belief can be held with absolute certainty. Instead, he held that people must rely on what seems most probable or plausible. Carneades famously used a bold dialectical method – arguing both sides of an issue – to expose weaknesses in his opponents’ claims. In particular, he challenged the Stoic philosophers’ dogmatic insistence on certain knowledge. Though he wrote nothing down, his teachings (recorded by later authors) made lasting contributions to Hellenistic philosophy by refining skeptical ideas and introducing what we might now call a fallibilist or probabilistic approach to knowledge.

Early Life and Education

Carneades was born around 214 BC in Cyrene, a Greek-speaking city in North Africa. Little is known of his childhood, but as a young man he traveled to Athens, the intellectual center of the Greek world. There he studied philosophy in Plato’s Academy (founded by Plato) and also with Diogenes of Babylon, a leading Stoic. This dual training exposed him both to the skeptical arguments of Plato’s school and the rigorous logic of Stoicism. He admired the Stoic philosopher Chrysippus (Diogenes’ teacher) so much that he reportedly remarked, “If Chrysippus had not been, I would not have been,” acknowledging the depth of Stoic influence on his thought.

Carneades excelled as a speaker and argumentor. By the mid-2nd century BC he rose to become scholarch or head of the Academy (succeeding earlier leaders like Lacydes). Under his leadership the Academy became known as the “New” or “Third Academy,” noted for throwing its support behind skeptical arguments. Like his predecessor Arcesilaus, Carneades made no attempt to systematize a positive doctrine; instead, he taught largely by oral debate in what later writers call a Socratic or dialectical spirit. His reputation for sharp questioning and wit earned him great influence in Athens and eventually beyond it.

Major Works and Ideas

Carneades left behind no written works, so our knowledge of his ideas comes from accounts by students and later philosophers (notably Cicero and Sextus Empiricus). He is celebrated for deepening the skeptical turn that Arcesilaus began in the Academy. Rather than offering a new set of doctrines, he honed the Academy’s focus on the limitations of human knowledge. In particular, Carneades advanced the view that we should suspend judgment on the ultimate truth of most claims. Because no criterion of truth is totally reliable, he argued, even our strongest convictions must remain tentative.

Some key elements of Carneades’s thought include:

Probabilistic criterion: Instead of certain knowledge, Carneades proposed a standard of probability (Greek pithanon). He coined the idea of the persuasive or plausible impression. In his view, our minds receive impressions from experience, but none can be proved infallibly true. The best we can do is to take seriously the impression that seems most convincing – i.e. the pithanon. For example, if in a dark room a coiled object looks like a rope, we treat that perception as a guide only if it survives careful testing (like poking it with a stick to make sure it is not a snake). This “three-stage” check – initial persuasiveness, freedom from contradiction with other impressions, and thorough examination – helps us act on what is likely true without ever claiming absolute certainty.

Suspension of belief: Carneades taught that a wise person will withhold full assent (agreement) from any dogmatic claim. Knowing that perceptions and reasoning can err, one should maintain a constant readiness to revise one’s views. Nonetheless, humans must still act and decide on matters of daily life. Carneades resolved this by allowing a kind of provisional assent: one may follow the most persuasive impressions and form opinions about them, but always acknowledging they might be wrong. In modern terms, this resembles fallibilism: we hold beliefs lightly and remain open to doubt. Some of his followers (like Philo of Larissa) said Carneades endorsed acting on probable opinions, while others (like Clitomachus) interpreted him more strictly as forbidding firm belief. This disagreement itself shows how carefully Carneades tried to balance skepticism with practical living.

Critique of Stoic epistemology: The Stoics had claimed that certain sense-perceptions, which they called “cognitive impressions,” were guaranteed true by nature. Carneades attacked this claim on several fronts. For example, he asked if a wise person could ever reliably distinguish between two nearly identical objects (say, two grains of sand). If not even a perfect sage could tell them apart, then seemingly clear impressions could still deceive. He also argued that people acting on false perceptions (for instance, a mad person acting on what they falsely perceive) seem indistinguishable in behavior from those acting on true perceptions. Thus, even an “impression” that feels absolutely convincing might be flawed. Overall, Carneades concluded that no impression of the senses or intellect is so self-evident that it can serve as an absolutely certain criterion of truth. Having undermined the Stoics’ epistemic foundation, he then offered probability as an alternative for guiding thought and action.

Ethical proposals (for argument’s sake): In ethics Carneades followed a systematic approach often attributed to him: he classified all competing theories of what constitutes the good life. He assumed people naturally pursue pleasure, freedom from pain, or other natural advantages. From this starting point, he deduced nine possible views about the goal of life by combining three “objects” (pleasure, absence of pain, natural advantage) with the idea of acting on purpose (virtue) or in fact succeeding. For instance, one view is that virtue alone is the highest good (as the Stoics held), another that actual pleasure is the highest good, and so on. Carneades would defend one of these views strongly on one occasion and another view on a different occasion – again arguing “in both directions” – to show that reasonable arguments could be made for multiple positions. It is unclear whether he himself held any of these positions or used them mainly to test Stoic assumptions. In any case, his goal was to demonstrate that Stoic ethical dogmas were not the only coherent options.

Free will and fate: Carneades also took part in debates about fate, determinism, and free will (reported in Cicero’s works). Unlike the strict Stoic determinists or the Epicurean random chance of the atomic swerve, Carneades suggested that true statements about the future need not imply that everything is predetermined. He argued that a future-true proposition being true does not force fate; it merely describes how events will turn out without committing to a chain of necessary causes. In other words, the way we use language about the future (truth and falsity of statements) can be understood without insisting on strict determinism or on introducing random atomic tics. This nuanced view aimed to preserve both logical consistency and a kind of spontaneity or moral responsibility in human action. (This technical issue is seldom emphasized in broad sketches of his philosophy, but it shows his subtlety in untangling difficult questions.)

In all these contributions, a common thread is that Carneades was looking for a way to live rationally despite the fact that ultimate certainty is unattainable. He held up probability, not as a second-rate substitute, but as the best tool we have to steer through life.

Method

Carneades is especially remembered for his dialectical method of argumentation. The term dialectical here refers to the Socratic-style questioning and debate approach: rather than lecturing with fixed doctrines, he engaged interlocutors by raising questions, examining their assumptions, and deriving conclusions that often contradicted their original stance. Importantly, he frequently argued “in utramque partem” (Latin for “on both sides”). That is, he would exert every effort to defend a thesis on one occasion and then turn around and argue it false on another occasion. His purpose was never to promote one side as the final truth, but to show that any claim could be challenged – thus encouraging suspension of judgment.

For example, during a famous (though possibly apocryphal) philosophical embassy to Rome in 155/154 BC, Carneades is said to have delivered two speeches on successive days: on the first day he defended justice as a supreme good, and on the second day he tore apart the same arguments to claim that justice might actually harm people. This theatrical demonstration forced his listeners to see that persuasive rhetoric could make even an upright idea appear suspect. It illustrated Carneades’s teaching that one should never accept a position without scrutiny. While modern scholars debate whether this exact incident happened as told, the story captures the essence of his style: he always took positions purely for the sake of argument.

In everyday teaching, Carneades’ dialectic involved asking his students and opponents to agree to simple premises and then using logical moves to draw out an opposing conclusion. He would not assert his own contradictory thesis as dogma, but used it to reveal tensions in the accepted view. For instance, he might accept a Stoic premise in debate and then show it led to an absurd result, thereby prompting re-examination. This form of non-committal argument (often called “skeptical dialectic”) allowed him to challenge Stoics, Epicureans and all comers without ever laying claim to a rival dogmatic system.

Overall, Carneades’s method can be summarized as follows:

* Playing devil’s advocate: Proclaiming strong arguments for a position and then equally strong arguments against it, to test the robustness of each view.

Questioning assumptions: Utilizing the question-and-answer format à la Socrates to force opponents to own premises, then showing how those premises lead to questionable conclusions.

* Suspension of personal commitment: Refraining from endorsing any proposition himself. He treated every argument as hypothetical—useful for examining ideas, but not something he insisted he personally believed. This attitude made him a liminal figure: a “skeptic” who did not set up his own theories, only critiqued those of others.

By these means, Carneades sharpened the skeptical approach: he taught people not to assert knowledge they could not prove, while still engaging fully in debate. His style was highly influential in the Academy and in later tradition as an exemplar of critical philosophizing.

Influence

Carneades’s impact was felt in his own time and extended through the centuries via later writers. As scholarch of the Academy, he guided its direction toward a more structured skepticism, and his arguments dominated discussions in the Academy until its closure. Two of his pupils carried on after him: Clitomachus (Greek Klietomachos, 2nd century BC) became head of the Academy after Carneades and later recorded much of his teacher’s reasoning in now-lost works. Another student, Philo of Larissa (c. 159–84 BC), also succeeded as scholarch. Philo, who spent his later years in Rome, is credited with softening Academic skepticism by explicitly allowing the acceptance of what seems most probable, an idea he may have developed from Carneades’s teachings.

In the wider world, Carneades helped spark Roman interest in Greek philosophy. The embassy to Rome in 155 BC is often cited as one of the first major introductions of Greek philosophical debate to Roman audiences. Cicero (1st century BC), the great Roman orator and philosopher, was a devoted student of Academic Skepticism. He frequently mentions Carneades in his dialogues. Cicero’s writings—the *Academica, De Republica, De Finibus, and others—preserve many of Carneades’s arguments and techniques (sometimes through fictionalized interlocutors). Through Cicero (and later via Sextus Empiricus, a 2nd-century AD skeptic), Carneades’s ideas entered the Western philosophical heritage.

Carneades’s emphasis on probability and argument influenced later epistemology. Modern scholars sometimes call his approach an early example of fallibilism or probabilism: the notion that all knowledge is tentative and that we proceed by weighing evidence and likelihoods. The very term “probable” (Latin probabile) in Roman philosophy often goes back to Carneades’s concept of pithanon. In rhetoric, the phrase “Carneadean fallacy” (Jean-Jacques Rousseau coined) refers to a fallacious reversal of an argument, reflecting Carneades’s habit of inverting debates.

More broadly, Carneades stands as a key figure in the history of skepticism. He represents the high point of Academic Skepticism, as distinguished from Pyrrhonian Skepticism. (The Academy’s skeptics argued about knowledge, while Pyrrho’s followers emphasized ataraxia—a peace of mind from suspending judgment on all issues.) Even today, discussions of doubt and certainty often recall Carneades’s legacy: his arguments are studied as classical examples of how to question epistemic dogmas.

Among his notable influences:

* *Students and successors: Clitomachus and Philo preserved and interpreted his teachings. Clitomachus famously admitted never fully understanding what Carneades himself believed, but he committed to the spirit of radical doubt. Philo, teaching in Athens and later Rome, taught Cicero and helped blend skepticism with a quasi-Platonic outlook. * *Roman intellectual life: By bringing skeptical dialectic to Rome, Carneades inspired thinkers like Cicero to explore probability and to appreciate dialectical reasoning. His memory encouraged Roman aristocrats to patronize philosophical schools. * *Hellenistic philosophy: In the Hellenistic era, Carneades’s challenge to Stoicism invigorated debates across schools, forcing Stoics to refine their epistemology and others to justify their first principles more rigorously. * *Long-term tradition: Renaissance and Enlightenment philosophers encountered Carneades via Cicero and Sextus. His name lives on in discussions about reasoning, as when an argument “is answered as if Carneades were answering you” – meaning that every counterargument is poised as if it were answering the very claim you just made. In sum, Carneades left behind a method of skeptical inquiry and a vocabulary of probability that continued to resonate in Western thought.

Critiques

Carneades’s philosophy did not go unchallenged. His most obvious opponents were the Stoics, whose very approach to knowledge he undermined. Stoic philosophers replied by refining their notion of the cognitive impression, (for example, adding that such an impression must be “unimpeded” by false appearances) and by arguing that the scenarios Carneades imagined were impossible in principle. They rushed to defend their system, holding that the existence of cognitive impressions (which, by definition, cannot come from what is not) still provided a secure way to assent to truth. Stoics likely felt that Carneades’s tactics threatened the coherence of philosophy by making it seem like anything could be doubted, thereby casting skepticism as a threat to rational life.

In practice, the dialectical approach itself drew criticism. Some ancient commentators accused Carneades of being merely rhetorical. They said he could “beat all conceivable arguments with others” as if he was running an intellectual swindle. Clitomachus, his own student, famously said he never understood what positive view Carneades truly held; from this some infer that Carneades himself was noncommittal to a fault. Others, however, thought he did commit to guiding principles of probability, and they faulted him for inconsistency if he ever let himself fall back into anything like dogmatism. (This debate continues among modern scholars: was Carneades secretly sceptical only for show, or did he genuinely allow a practical endorsement of the probable?)

Within the Academy, there was also split. Philo and some later Academics leaned toward accepting probable opinions, while Clitomachus and the more radical skeptics insisted on complete suspension of belief. The Pyrrhonian skeptics of the 1st century BC and after went even further than the Academics, saying one should make no even partial commitments – a stance they saw as not possible for Carneades, since he at least talked about being persuaded by plausibility.

Finally, critics sometimes note a potential paradox: if Carneades truly believed nothing could be known, how could he know that? His very act of philosophizing on this theme seems to assume some knowledge of logic and perception. He would respond that he was not offering any final truth, only tools to test others’ beliefs; nevertheless, this vein of skepticism has long been accused of being self-defeating. Even ancient skeptics (like Sextus Empiricus) point out that denying the possibility of knowledge is impossible to assert without at least thinking one knows something (the statement that nothing is knowable seems asserted as if it were known). Carneades navigated this by framing all his theses as provisional and dialectical, but critics still debate whether he ultimately avoided paradox.

Legacy

Carneades’s legacy lies in the skeptical tradition and in the idea of probable truth. He is often remembered as the pinnacle of the Academic skeptics, bringing their methods to full flower. In practical terms, the key insight that absolute certainty is elusive but that human beings can and must act on what seems right has resonated beyond antiquity. Modern epistemologists frequently trace the notion of fallible justification back to thinkers like Carneades.

One concrete legacy is linguistic: the adjective “Carneadean” (or “Carnedean”) came to describe a cunningly deceptive or contradictory argument, reflecting how Horace and later writers caricatured Carneades’ method of switching sides. In academic philosophy, his work helped launch the medieval and Renaissance revival of skepticism through Cicero’s work. During the Enlightenment, figures like Pierre Bayle and David Hume, who grappled with skepticism and belief, were indirectly influenced by this Hellenistic source.

Today, Carneades is not as well-known as Plato or Aristotle, but among philosophers and classical scholars he is a figure of enduring interest. His example of disciplined doubt reminds us that questioning what we think we know is always within the philosopher’s toolkit. In areas like probability theory and the philosophy of science, his move toward accepting probabilistic justification anticipates later ideas (for instance, the scientific practice of treating evidence as confirming hypotheses only tentatively). In any case, Carneades’s name still stands for a bold refusal of dogmatism: he showed that to pursue knowledge wisely one must think twice before claiming any certain conclusion.

Selected Works

Carneades himself left no surviving writings. What we know comes from secondary sources that report his speeches and arguments. Important works in which Carneades appears include:

Cicero’s Dialogues: Cicero reports Carneades’s views in several works. In Academica (especially Book II) and in De Republica (Book III, in the speech for Philus), Cicero re-creates debates on knowledge and justice that reflect Carneades’s arguments. De Finibus Bonorum et Malorum (concerning ethics) also conveys Carneadean positions, as does Tusculanae Disputationes (concerning emotional resilience in misfortune).
Sextus Empiricus, Outlines of Pyrrhonism: This 2nd-century AD work on skepticism uses Carneades as a representative of the Academic (“late Academic”) school. It summarizes some of his skeptical arguments and contrasts them with the Pyrrhonian view.
Diogenes Laertius, Lives of Eminent Philosophers: In Book IV (which covers Plato and the Old Academy), Diogenes gives brief biographical details about Carneades and his philosophy, quoting anecdotes and summarizing opinions of later Academics.
Other ancient writings: Carneades is also mentioned in Plutarch (in works on Stoic/Academic debates), Cicero’s De Natura Deorum (on theology), and in various doxographies (collections of doctrines) by later writers. These sources collectively preserve the picture of his thinking.

No “title” of Carneades’s own survives; the above are examples of ancient texts that discuss him or the arguments attributed to him. Modern readers must rely mainly on these transcripts to reconstruct Carneades’s legacy.

Timeline

c. 214 BC – Carneades is born in Cyrene (in modern-day Libya).
c. late 200s–early 190s BC – Travels to Athens to study philosophy. Trains at Plato’s Academy and with Stoic Diogenes of Babylon.
c. 155 BC – As head of the Academy, Carneades (along with Stoic philosopher Diogenes of Babylon and Peripatetic Critolaus) leads a delegation to Rome to represent Athens. According to tradition, he delivers famous successive speeches on justice (one day defending it, the next attacking it) to demonstrate his skeptical method.
155–129 BC – Continues to lead and teach in Athens. Influences the direction of Academic skepticism. Encourages doubt and the use of probabilistic reasoning in philosophy.
129/128 BC – Dies in Athens (approximately 85 years old). His students, like Clitomachus and Philo, carry on his skeptical legacy in the Academy.

This timeline highlights the main events of Carneades’s life and career, though specific dates (especially for his early life) are approximate. The core of his work took place in the mid-2nd century BC, a vibrant era of dialogue among the Academy, Stoic, and other Hellenistic schools.