Arcesilaus and the Academics

⊕ Arcesilaus, 315-240 BCE.
Succeeded Crates (5th head of the Academy) and become the first head of the "New" Academy.

Carneades, 214-129 BCE.
10th head and Arcesilaus's most distinguished successor.

Clitomachus, 187-110 BCE.
13th head of the Academy.

Philo of Larisa, 160-83 BCE.
Succeeded Clitomachus and was the last head of the Academy.

Antiochus, 1st century BCE.
Broke from the New Academy to reestablish the "Old" Academy.

Aenesidemus, 1st century BCE.
To recover the skepticism he thought was lost under Philo's leadership, Aenesidemus broke away to found a skeptical movement under the name of Pyrrho.

Pyrrho lived in the 4th to 3rd century BCE.
He seems to have pursued a skeptical way of life but wrote nothing and established no school. Plato died in 347 BCE. The Academy itself continued under new leadership.

When Arcesilaus became the head of the Academy in 267 BCE, he refocused attention on the Socratic practice of asking questions to expose the pretense to knowledge.

Cicero refers to the Academy with this changed focus as "the New Academy" (Academica I.46).

Within the New Academy, there was a dispute about how to understand whether the Academics themselves had knowledge. This dispute defined much of the work in the school, and disagreements about its solution contributed to the breakup of the school.

Against Stoic Epistemology

⊕

Cicero, 106-43 BCE.

The Academica (consisting in two books) is a reconstruction taken from fragments of the Academica Priora and the Academica Posteriora. The Academica Priora contained the Lucullus and the Catulus. The Academica Priora contained the Academic Books. The Catulus and all but part of the first of Academic Books have been lost. Book I of the Academica is what remains of the Academic Books. Book II is the Lucullus. Most of what is known about the Academics in this period depends on Cicero. In his Academica, he sets out the argument between the Academics and the Stoics.

In this argument, Arcesilaus plays Socrates to Zeno.

⊕

"It wasn’t a spirit of intransigence or rivalry that gave rise to Arcesilaus’s extended disagreement with Zeno, but the obscurity of things that had previously led Socrates to his confession of ignorance.... That’s why Arcesilaus used to deny that anything could be known, not even the residual claim Socrates had allowed himself, i.e., the knowledge that he didn’t know anything. He thought that everything was hidden so deeply and that nothing could be discerned or understood. For these reasons, he thought that we shouldn’t assert or affirm anything, or approve it with assent: we should always curb our rashness and restrain ourselves from any slip. But he considered it particularly rash to approve something false or unknown, because nothing was more shameful than for one’s assent or approval to outrun knowledge or apprehension" (Academica I.44). Zeno made "new pronouncements" about impressions, assent, and knowledge (Academica I.40). Arcesilaus countered that "that nothing could be discerned or understood" and that we should not "assert or affirm anything, or approve it with assent" (Academica I.45).

The Academics refer to their suspension of assent as ἐποχή or "holding back."

We can wonder whether Arcesilaus, in his counter to the new prouncements, does hold back. He seems to say that no one should "assert or affirm anything, or approve it with assent." Yet, in advancing this view, it appears that he is assenting to something and thus is not taking his own advice. He appears to be saying that he knows that no one knows anything.

The appearance of contradiction here created a problem for the Academics.

They needed to explain how arguing against Stoic epistemology in they way Arcesilaus does in his argument with Zeno is consistent with the "holding back" that defines the school.

Looking back to Socrates

To understand the Academic attempt to solve this problem, it helps first to know that the Stoics and the Academics both looked back to Socrates but saw different things.

The Stoics thought that Socrates showed that although knowledge is difficult to obtain, it is not impossible to obtain. As they understood him, he showed that knowledge consists in assent no rational means can force one to withdraw. The Stoics thought that such assent is possible because nature in its providence arranges things so that human beings can learn to give their assent to cognitive impressions. The beliefs someone forms by assenting to these impressions are true. Moreover, in the absence of false beliefs, questioning cannot force someone to withdraw a belief that consists in an assent to a cognitive impression because no valid argument constructed from premises he believes has the negation of one of his beliefs as its conclusion.

⊕
"Arcesilaus asked Zeno, we [Cicero speaks a representative of the Academy] may suppose, what would happen if the wise man couldn’t apprehend anything, but it was a mark of wisdom not to hold opinions. Zeno replied, no doubt, that the wise man wouldn’t hold any opinions because there was something apprehensible. So what was that? An impression. What kind of impression? Zeno defined it thus: an impression from what is, stamped, impressed, and molded just as it is. After that, Arcesilaus went on to ask what would happen if a true impression was just like a false one. At this point, Zeno was sharp enough to see that no impression would be apprehensible if one that came from what is was such that there could be one just like it from what is not. Arcesilaus agreed that this was a good addition to the definition, since neither a false impression, nor a true impression just like a false one, was apprehensible. So then he set to work with his arguments, to show that there is no impression from something true such that there could not be one just like it from something false" (Academica II.77).


"[T]he way in which they [the Academics] harp on cases of resemblance between twins or between the seals stamped by signet-rings is childish. For which of us [Lucullus speaks as a representative of the Stoics] denies that resemblances exist, since they are manifest in ever so many things? Yet if it is enough to do away with apprehension that many things are similar to many others, why aren’t you satisfied with that, especially when we concede it? Why do you go on to maintain something the nature of things does not permit, by denying that each thing is in its own kind and just as it is, i.e., that there aren’t any shared features that don’t differ at all between two or more things? Take it as granted that eggs are very similar to eggs, and bees to bees: what are you fighting for? What are you driving at with your twins? That they are similar—the point with which you could have been satisfied—is conceded; but your idea is that they aren’t similar but identical, which cannot happen [because indiscernibles are identical]" (Academica II.54).


It is important to distinguish the identity of indiscernibles from the indiscernibility of identicals.

The indiscernibility of indenticals is the thesis that if x = y, then x and y have all and only the same features.

This thesis is appears to be a truth about identity. The identity of indiscernibles is more controversial. In their opposition to the Stoics, the Academics did what they thought Socrates did.

Socrates questioned his interlocutors and used their answers as premises in argument for a conclusion they thought was contrary to their initial answer, and the Academics took Socrates to conclude that someone refuted in this way did not know what he thought he knew. Further, none of Socrates' interlocutors survived his questioning. This seemed to show that no matter how much care someone takes in forming his beliefs, it is possible that someone like Socrates could show them that they do not know what they think they know.

Arcesilaus's Argument

Against this background, and given how Cicero imagines the exchange between Zeno and Arcesilaus, the following is a natural way to set out Arcesilaus's argument:

1.  For every true impression, there could be a false one just like it.
2.  If (1) is true, then there are no cognitive impressions.
3.  If there are no cognitive impressions, then it is necessary to withhold assent.
4.  If it is anecessary to withhold assent, then knowledge is impossible.
----
5.  Knowledge is impossible.

This argument is valid. The Stoics accept (2), (3), and (4). In Cicero's account, Arcesilaus tried to show that (1) is true. He "set to work" to show that "there is no impression from something true such that there could not be one just like it from something false."

One way Arcesilaus and the Academics tried to show this, as Lucullus puts the point from the Stoic point of view, is by "harp[ing] on cases of resemblance between twins."

The idea, it seems, is that if someone could easily have been wrong in a similar case, he does not have knowledge because there is an argument to force him to withdraw his assent.

Suppose that a and b are twins, that a is walking toward me, that I get an impression that a is walking towards me, and that I assent to this true impression. In this situation, it seems that it would have been very easy for me to have assented instead to a false impression that b is walking toward me. If this is true in general, as the Academics think, the Stoics themselves believe that no impression is cognitive and hence that knowledge is impossible.

Zeno, though, as Cicero sets out the dialectic, was "sharp enough" to deny (1).

Zeno and the Stoics believe in the identity of indiscernibles: that if x and y have the same features, x and y are identical. It follows, since they are not identical, that some feature distinguishes a from b, and the Stoics think that with practice I could learn to assent in the situation in such a way that I know that a, not b, is the twin walking toward me.

The Stoics do not mean that we can learn to distinguish every pair of things, but they think we can learn to give our assent only when our impression is cognitive and that nature gives us such impressions for the parts of reality we need to grasp in order to live good lives.

How the Academic forms Beliefs

To understand how Arcesilaus's argument is consistent with the "holding back" that defined the Academy, it is crucial to keep in mind that he, like Socrates, is arguing dialectically.

In dialectic, as we have seen, the questioner tries make the respondent contradict himself. The questioner does not need to believe the premises he gets the respondent to accept. Nor does he need to believe that the argument he gets the respondent to accept is valid.

At the same time, nothing in dialectic prevents the questioner from having beliefs. ⊕ So, if the Academics have beliefs, as surely they do, how do they form them?

Assent to Persuasive Impressions

⊕ "'Carneades’s view is that there are two categories of impressions, the first subdivided on the principle that some impressions are apprehensible, some aren’t, the second on the principle that some impressions are persuasive (probabilia), some aren’t. Now the Academic arguments against the senses and against perspicuity pertain to the first category, and shouldn’t be directed at the second. So his view’, Clitomachus says [Cicero is quoting from the first book of Clitomachus's no longer extant On Suspending Assent], ‘is that while there are no impressions allowing for apprehension, there are many allowing for approval. It would be contrary to nature were there no persuasive impressions’—and the result would be the complete overturning of life" (Academica II.99).

"[Because Carneades] himself too requires a criterion for the conduct of life ..., he is practically compelled on his own account to frame a theory about it, and to adopt both the persuasive impression and the impression which is at once persuasive and irreversible and tested" (Sextus Empiricus, Against the Logicians I.166).

"[J]ust as in ordinary life when we are investigating a small matter we question a single witness, but in a greater matter several, and when the matter investigated is still more important we question each on the testimony of the others,--so likewise, says Carneades, in trivial matters we employ as criterion only the persuasive impression, but in greater matters the irreversible, and in matters which contribute to happiness the tested impression (Sextus Empiricus, Against the Logicians 1.184). Carneades was responsible for an important part of the answer to this question.

We can see his answer in his reponse to a Stoic argument.

The Stoics tried to turn the tables on the Academics. The Academics tried to show the Stoics that they had beliefs that commit them to thinking that knowledge is impossible. The Stoics, in turn, argued that if knowledge is impossible, rational action is impossible.

5.  Knowledge is impossible.
6.  If (5) is true, then assent is not permitted.
7.  If assent is not permitted, rational action is impossible.
----
8.  Rational action is impossible.

The Stoics are trying to show the Academics that since they believe rational action is possible, they are committed to denying (1) in their counter to the new pronouncements.

In his response to this argument, Carneades explains how we could assent in the absence of cognitive impressions. We could accept that knowledge, as the Stoics understand it, is impossible but go on to live our lives in the way human beings ordinarily do. We could assent to impressions in terms of their persuasiveness and act in terms of the beliefs we form.

We could, he means, consider something that interests us until we have the evidence to decide it one way or another given the importance we attribute to it. When we have the evidence, we assent and come to believe the matter is as our thinking has shown it to be.

This Assent is Rational

Carneades seems to be right that this what we ordinarily do, but it does not follow that doing it is rational. So, as a denial of premise (6), the Academics need to do more. They need to explain why the method of assent Carneades described is rational and thus is permitted.

The Stoics can explain why their method of assent is rational. They think that nature arranges things so that the beliefs formed by assenting to cognitive impressions are true.

What can the Academics say to show that the assent Carneades described is rational?

The evidence is extremely limited, but it appears that Clitomachus and Philo (the subsequent heads of the Academy after Carneades) gave different answers to this question.

Clitomachus

Clitomachus distinguishes two ways to withhold assent. Someone could withhold "absolute assent" from every impression or "restrain himself from replying" to every impression.

Clitomachus thinks the "wise" man withholds assent the first way but not the second.

The wise man witholds "absolute assent" to from every impression he gets. He does not, however, "restrain himself from replying" to every impression he gets. Sometimes he says 'yes' or 'no' to his impressions, and hence "convey[s] approval or disapproval" in such a way that he follows his impressions in terms of whether he finds them persuasive or not.

⊕ "[I]n the book Clitomachus wrote, ... he pretty much used these words—I [Cicero] know them well, because the basic primer, as it were, for the subjects currently at issue is contained in this book" (Academica II.102).


"he gives absolute assent to no impression at all."

The Latin is omnino eum rei nulli adsentiri. If the adverb omnino modifies the verb adsentiri, not the object of the verb rei nulli, the translation is "he gives assent to nothing absolutely [or: entirely]." Otherwise, it is "assent to nothing at all." The Loeb translator tries to have it both ways. For Clitomachus's understanding of Academic assent, we are dependent on Cicero. He takes his interpretation of Clitomachus from a now lost book Clitomachus wrote.

"[Clitomachus says] that the wise man is said to withhold assent in two ways. One when the meaning is that he gives absolute assent to no impression at all The other when he restrains himself from replying so as to convey approval or disapproval of something, with the consequence that he neither makes a negation nor an affirmation. Clitomachus holds that he [the wise man] never assents, but that he is guided by persuasiveness, and wherever this confronts him or is wanting he can answer yes or no accordingly" (Academica II.104).

Who is the "wise man"?

He is someone who is perfectly rational.

What is "absolute assent"?

It seems to be a way of talking about the Stoic method of assent. When the Academic forms beliefs, he does not take the himself to do what the Stoics claim they themselves do.

What does the Academic take to himself to do?

He tries to do what he takes the wise to do.

The wise man says "yes" or "no" to his impressions in terms of their persuasiveness. If the impression is persuasive, he says "yes" to the impression and is "guided" by its content. If it is not persuasive, he says "no" to the impression and is not "guided" by its content.

What is "guided"?

⊕ The evidence for this interpretation is not completely clear.

"This is the one disagreement still outstanding... [that the wise man] might perceive nothing and yet form an opinion—a view which Carneades is said to have approved; although, since I trust Clitomachus more than Philo or Metrodorus, I believe that Carneades did not so much approve this as advance it in argument" (Academica II 78).

"I agree with Clitomachus when he writes that Carneades really did accomplish an almost Herculean labour in ridding our minds of that fierce wild beast, the act of assent, that is of mere opinion and hasty thinking" (Academica II 108).

"Clitomachus used to declare that he had never been able to understand what Carneades did accept" (Academica II 139).

"What is to hinder me from accepting what seems persuasive to me and rejecting the opposite, and so avoiding the presumption of assertion and escaping the recklessness that is so far removed from wisdom? We argue against everything on the grounds that we could not get a clear view of what is persuasive unless the two sides had been heard. I explained all this well enough, or so I think, in my Academics" (On Duties 2.8). One possibility is that to be "guided" by the content of an impression is to believe that the content is true and to make choices against the background this and other beliefs.

Because an impression can be persuasive but false, the wise man can have false beliefs.

Human Wisdom

Clitomachus understands wisdom to be like what Socrates calls human wisdom.

In his attempt to understand the oracle's response to Chaerephon, Socrates thought that the god was using him to show that "human wisdom is of little or no value" (Apology 23a).

What is "human wisdom"? Why is it "of little or no value"?

Socrates explains that his experience of questioning others left him with the following thought.

"I am wiser than this man; for neither of us really knows anything fine and good, but this man thinks he knows something when he does not, whereas I, as I do not know anything, do not think I do either. I seem, then, in just this little thing to be wiser than this man at any rate, that what I do not know I do not think I know either" (Apology 21d).

Here is one way to understand what Socrates has in mind.

Someone with human wisdom has a certain humbleness about his grasp on the truth. He is careful not to form his beliefs rashly, but he realizes that it is still possible for the god to send someone to show him that he cannot defend his beliefs in questioning.

This means that no matter how careful someone is in forming his beliefs, it always remains possible that he will come to think he had been wrong about things.

Socrates restricts his point to wisdom about "fine and good" matters.

The point, though, as the Stoics and Academics debate it, is more general. It is whether about any matter someone can have beliefs no rational means can force him to withdraw.

Philo of Larisa

When Philo was first elected as head of the Academy, he supported Clitomachus's views. ⊕ "This Philo, when he had just taken over the school, was overcome by joy, and he gratefully honoured Clitomachus and praised his doctrines" (Numenius, fragment 28).

Numenius of Apamea (2nd century CE), Platonist

At some point, though, Philo seems to have changed his mind. He seems to have thought that Clitomachus had not done enough to defend the assent Carneades identified.

The evidence for this interpretation is even more limited than the evidence for what Clitomachus thought because we do not have a passage like the one Cicero quotes from what Clitomachus wrote that tells us us how Philo understood Carneades.

This leaves us to look for an expression of the view Philo held. When we do this, one possibility is that Philo had the view Catulus says his father accepted. ⊕ Cicero seems to use Catulus to represent an interpretation of the Academy that contrasts with his own.

"'My view?' replied Catulus, 'I am coming round to the view of my father, which he used to say was ⊕ Socrates, in the Gorgias, can seem to have this view.

"My story, Callicles, is ever the same, that I do not know how these things are, and yet all of whom I have encountered, before as now, no one has been able say otherwise without making himself ridiculous. So once more I set down these things" (Gorgias 509a). Carneades's, and am beginning to think that nothing is apprehensible [graspable by assenting to a cognitive impression], but to deem that the wise man will assent to something he has not apprehended, that is, will hold an opinion, but with the qualification that he will understand that it is an opinion and will know that there is nothing apprehensible; and therefore although [in this way] agreeing with their rule of ἐποχή, I assent emphatically to that second view, that nothing exists that is apprehensible'" (Academica II.148).

The tone Catulus employs to describe his view is not present in Cicero's report of what Clitomachus says the wise man does to "convey approval or disapproval." Catulus expresses a confidence that contrasts with the humbleness of of simply saying "yes" and "no" to impressions and thus following them in terms of their persuasiveness.

Catulus's view, then, does not seem to be Clitomachus's, and this suggests it is Philo's.

Catulus does not explain why it is rational to assent in the way he describes, but maybe the explanation is the one Lucullus (who speaks for the Stoics) attributes to the Academics.

"What do you [Academics] mean by your persuasive impressions? If you mean that you rely on what strikes you and seems persuasive at, in effect, first glance, what could be sillier than that? But if they say that they follow impressions that arise from some examination or detailed consideration, they still won’t find any way out. ⊕ "The sole object of our discussions [Cicero speaks for the Academics] is by arguing on both sides to draw out and give shape to some result that may be either true or the nearest possible approximation to it. The only difference between us and philosophers who think that they have knowledge is that they have no doubt that the views they defend are true, whereas we hold many views to be persuasive, i.e., ones that we can readily follow but scarcely affirm" (Academica II.7).

"Their idea [the idea of those who distinguish being unclear from being inapprehensible] is—and I [Lucullus, who speaks for the Stoics] noticed that you [Academics] were particularly moved by this—that there are ‘persuasive’ or, as it were, ‘truth-like’ (veri simile) impressions, and this is what they use as their guiding rule both for conducting their lives and in investigation and argument" (Academica II.32).

Lucullus’s use of 'as it were’ suggests that veri simile is not a synonym of 'persuasive' but intead is an explanation for why assent to persuasive impressions is rational. ... [For even if] they allow that after the wise man has played his part thoroughly by subjecting everything to a meticulous examination, it’s still possible for his impression to be truth-like (veri simile) and yet very far from being true. So even if they do approach the truth for the most part or its closest approximation, as they say they do, they still won’t be able to be confident in their claims" (Academica II.36).

Lucullus he takes the Academics to think that the justification for their assent in terms of persuasive impressions is that the beliefs they form in this method are “truth-like.”

Lucullus thinks this answer is not enough to justify the Academics's "confiden[ce] in their claims" because "truth-like" is compatible with "vary far" from true. Philo's explanation of the rationality of the assent Carneades described is thus unacceptable because it does not rule out the possibility that the world is very different from how the beliefs represent it to be.

Justification of Academic Assent

What, on this interpretation, is the difference between Clitomachus's and Philo's views?

Both allow the Academic to have "confiden[ce] in their claims."

Clitomachus, however, tells no story about about how following the method of assent Carneades described is rational because it results in beliefs that are true or at least "like" the truth. Nor does Clitomachus seem to think such a story is necessary.

The question Clitomachus has to answer to meet the Stoic challenge is whether the Stoic method of assent in terms of cognitive impressions is better than the method in terms of persuasive impressions Carneades had identified as the ordinary way we give assent. Since the Academics think there are no cognitive impressions, Clitomachus's answer is that the Stoic method is not better and thus that the Academic should keep saying "yes" or "no" to their impressions in terms of the persuasiveness of these impressions. Clitomachus thinks that this way of assenting to form beliefs is rational and that the Stoics have not provided a reason to abandon it for their new method in terms of cognitive impressions.

Philo thought it was necessary to say more than what Clitomachus said.

To justify the method of assent Carneades identified, Philo says that the beliefs formed in terms of this method are "like" the truth if they are not the truth. He thinks that this fact about the method is what makes it a rational method for giving assent and forming beliefs.

Philo thus takes a position similar to the one the Stoics take to justify their method of assent.

The Stoics think that their method of assent is rational because nature in its providence arranges things so that this method of assent gives us knowledge. It is not clear what view if any Philo puts in the place of this Stoic view about nature, but he seems to have thought that the method of assent Carneades described is rational because this method in terms of persuasive impressions gives us beliefs at least "like" the truth if they are not the truth.

The Academy breaks into Rival Factions

⊕ "They had heard these doctrines from Philo at Rome" (Academica II.11).

"Philo asserts that things are inapprehensible (ἀκατάληπτα) so far as concerns the Stoic criterion, that is to say cognitive impression, but are apprehensible so far as concerns the nature of the things themselves" (Sextus Empiricus, Outlines of Pyrrhonism I.235). In his "Roman" Books (lectures he gave in Rome in 88 BCE), Philo moved closer still to the Stoic's position in the debate over the possibility of knowledge.

The evidence again is limited, but Philo's view seems to be that although there is no knowledge as the Stoics conceive of it (in terms of assent no rational means can force one to withdraw), someone has knowledge if he assents to a true persuasive impression.

How does this view fit with the method of assent Carneades described?

Suppose that I assent to an impression and thus from a belief because I have thought about the matter carefully in a rational way and am persuaded that the propositional content of the impression is true. Suppose further that the propositional content of the impression is true. Is my belief knowledge? Or is it merely opinion because someone might question me and force me to withdraw my assent so that I can hold on to other beliefs I possess.

Philo, in his Roman Books, seems to have said that such a belief is knowledge.

This answer did not sit well with many in the Academy, and this together with the destruction of the grounds of the Academy caused the school to break apart.

Philo give the lectures called his "Roman" books when he had taken refuge in Rome to avoid the destruction Rome was inflicting on Athens in the Mithridatic War. This descruction reaached the Academy. In 86 BCE, as part of the brutal seige of Athens and the Piraeus the Roman general Sulla started in 87 BCE, he laid waste to the grounds of the Academy.

Two years later, in 84 BCE, Philo himself died.

Now, without a head and a physical location to meet, and with disagreement within the school about Philo's view in his Roman Books, the Academy disappeared into rival factions.

⊕ Aenesidemus denigrates the Academics of his day as "Stoics fighting with Stoics" (Photius, Bibliotheca 212.170a16) Photius (9th century CE), Ecumenical Patriarch of Constantinople. His Bibliotheca consists in notices of works in his library, almost half of which are now lost. Notice 212 is of "the eight books of Pyrrhonian writings by Aenesidemus" (Bibliotheca 212.169b).

βιβλιοθήκη means "library, collection of books." Aenesidemus (1st century BCE) led one of these factions.

In an attempt to return to what he thought of as the skepticism lost under Philo, Aenesidemus founded a breakaway skeptical movement under the name of Pyrrho.

This movement is Pyrrhonian Skepticism.

Our knowledge of it's principles depends primarily on the much later description in Sextus Empiricus (a 2nd or 3rd century CE physician and philosopher).

"The natural result of any investigation is that the investigators discover the object of search, deny that it is discoverable and confess it to be not graspable, or persist in their search. ... The skeptics (σκεπτικοί) [are the investigators who] keep on searching. ... Our task at present is to describe this way in outline" (Sextus Empiricus, Outlines of Pyrrhonism I.1.1). ⊕ "It seems reasonable that the main types of philosophy (φιλοσοφίαι) are thought to be three: dogmatic(δογματικὴ), Academic (Ἀκαδημαϊκὴ), and skeptic (σκεπτική)" (Outlines of Pyrrhonism I.1).

A diaeresis (two dots) is placed over a vowel Ἀκαδημαϊκὴ to indicate that the vowel is pronounced in a separate syllable. In English, "naïve" is an example.

"It is called Pyrrhonian because Pyrrho [4th to 3rd century BCE, about whom very little is known] appears to us to have applied himself to skepticism more thoroughly and more conspicuously than his predecessors" (Sextus Empiricus, Outlines of Pyrrhonism I.1.7).

We, in this course, do not try to understand Pyrrhonian Skepticism.

This course and these lectures end with breakup of the Academy in about 100 BCE, as this event traditionally marks the end of the Period of Schools in Ancient philosophy.

Perseus Digital Library:

Henry George Liddell, Robert Scott, A Greek-English Lexicon:
ἀκατάληπτος, (ἀ +‎ καταληπτός), akatalēptos, adjective, "not graspable, not comprehensible"
⊕ "[There is] an etymological and conceptual connection between πιθανόν (probable) and πείθεσθαι (to follow; cf. PH [Outlines of Pryrrhonism] I, 230). It is this connection which Cicero tries to preserve when he renders πιθανόν by probabile to make it correspond to the verb for 'approve' or 'accept' which he likes to use, namely probare (Cic. [Cicero], Ac. pr. [Academica II].99; [Academica II.]139). So the probable quite literally is that which invites approval or assent in the sense in which the skeptic is free to give assent" (Michael Frede, "The Skeptic's Two Kinds of Assent and the Question of the Possibility of Knowledge," 215. Essays in Ancient Philosophy, 201-222). πιθανός, pithanos, adjective, "persuasive, plausible"
πείθω, peithō, verb, "persuade"

Charlton T. Lewis, Charles Short, A Latin Dictionary:
adensio, noun, "assent"

"[L]et us say a few words on the subject of assent or approval (adsensione atque adprobatione), termed in Greek συγκατάθεσιν" (Academica II.37).

probabilis, adjective, "worthy of approval"
probatio, noun, "approval"
probo, verb, "to be satisfied with, to approve"
versimilis, adjective, (veri, noun, "true" + similis, adjective, "like"), "truth-like"

Arizona State University Library. Loeb Classical Library:
Cicero, Academica
Sextus Empiricus, Against the Logicians, Outlines of Pyrrhonism


"Carneades points out [in his response to the Stoic argument] that he will just follow the probable, what ⊕

What are the "two interpretations"?

One is that assent in terms of the persuasiveness of impressions is what human beings do. The other is that this method of assent is rational because the belief formed this way "if not true has a good chance to be true."

Frede goes on to say that only the second interpretation confers some "epistemological status"" on the method.

Clitomachus gives the first interpretation of Carneades.

Frede's view, then, seems to be that Clitomachus, in interpreting Carneades as he does, is not thinking that method of the assent Carneades described is rational.

I do not see the evidence for this. Clitomachus and Philo both think the method Carneades described is rational. They disagree about in what this rationality consists. seems to be the case, and that depending on the importance of the matter he will go through certain procedures to make sure that his impression is relatively reliable. It is clear that Carneades' account, first of all, is a dialectical move against a dogmatic objection and thus does not commit him to any view at all. But I also think that it does reflect Carneades' view of how people actually go about gaining an impression they are willing to rely on. And taken this way, it admits of two interpretations. It may be taken in just the sense that this is how human beings in general seem to proceed, or it may be taken in the sense that this is how one ought [how it is rational] to proceed if one wants to get a reliable impression, one which if not true, at least has a good chance to be true. Whereas on the first interpretation it is just noted that human beings, as a matter of fact, go about considering matters in a certain way when in doubt, on the second interpretation proper consideration is regarded as conferring some epistemological status on the impression thus arrived at: it has at least a good chance of being true, to be like the truth (versimilis), or else be the truth itself (Cic. [Cicero], Ac. pr. [Academica II] 7; 32; 66; 99; 107). On the other interpretation, the fact that something appears to be the case goes no way to show that it is true; however much it appears to be the case, this does not itself make it any more likely to be true. The probable is just the persuasive" (Michael Frede, "The Skeptic's Two Kinds of Assent and the Question of the Possibility of Knowledge," 214. Essays in Ancient Philosophy, 201-222. University of Minnesota Press, 1987).