Arcesilaus and the Academics

Skepticism in the New Academy

Arcesilaus, 315-240 BCE. Arcesilaus succeeded Crates (the fifth head of the Academy), changed the focus of the Academy, and initiated the "New" Academy.

Carneades, 214-129 BCE. Carneades (the tenth head of the Academy) is Arcesilaus' most distinguished successor.

Clitomachus, 187-110 BCE. Clitomachus is the thirteenth head of the Academy.

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

Antiochus, 1st century BCE. Antiochus broke away from the New Academy, tried to reestablish the "Old" Academy.

Aenesidemus, 1st century BCE. Aenesidemus broke from the New Academy to found a new 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).
Arcesilaus refocused the Academy by interpreting Plato's dialogues in terms of the Socratic practice of exposing the pretense to wisdom. There were disputes within the school about how to understand this skepticism. These disputes eventually gave rise to the establishment of a new school under the name of "Pyrrhonian skepticism." This happened in about 100 BCE.

Against the Stoic Pronouncements

Cicero, 106-43 BCE.

The Academica (which consists in two books) is a reconstruction on the basis of fragments from two works. The first work (Academica Priora) consists in the Lucullus and now lost Catulus. The second work (Academica Posteriora) consists in the Academic Books, of which only part of the first book is extant. Book I of the Academica is what remains of the Academic Books. Book II is the Lucullus.
Most of what is known about the Academy during this time depends on Cicero.

"It was entirely with Zeno [the founder of Stoicism], so we have been told, that Arcesilas set on foot his battle, not from obstinacy or desire for victory, as it seems to me at all events, but because of the obscurity of the facts that had led Socrates to a confession of ignorance.... Accordingly Arcesilas said that there is nothing that can be known, not even that residuum of knowledge that Socrates had left himself--the truth of this very dictum: so hidden in obscurity did he believe that everything lies, nor is there anything that can be perceived or understood, and for these reasons, he said, no one must make any positive statement or affirmation or give the approval of his assent to any proposition, and a man must always restrain his rashness and hold it back from every slip, as it would be glaring rashness to give assent either to a falsehood or to something not certainly known, and nothing is more disgraceful than for assent and approval to outstrip knowledge and perception" (Academica I.45).
Zeno of Citium (the founder of Stoicism) introduced what Cicero describes as "new pronouncements" in epistemology (Academica I.40). Arcesilaus countered these pronouncements. In opposition to the Stoics, he seems to have said that "that there is nothing that can be known" and that therefore "we should not assert or affirm anything, or approve it with assent" (Academica I.45). Given that Arcesilaus did say this and that in saying it he did not straightforwardly contradict himself, he cannot be understood to have assented to the view that no one should assent to any view. Still, because it remained unclear exactly how he should be understood, it became a problem within the Academy to understand his opposition to the Stoic pronouncements. This opposition became defining feature of the Academy because there was a serious worry that the school would be undermined if the problem went unsolved.

A Problem within the Academy

The Academics and the Stoics looked back to Socrates, but they saw different things. Socrates' questioning seemed to show that nobody had the knowledge necessary to live a good life, but Socrates did not abandon his questioning. Moreover, according to the Stoics, he was right not to stop because although knowledge is difficult to obtain, it is not impossible.

Knowledge is possible, according to the Stoics, because there are "cognitive impressions." Nature in its its providence gives human beings the ability to restrict their assent to cognitive impressions and thus allows them to have the knowledge they need. The beliefs they form by assenting to impressions are true. Moreover, in the absence of false beliefs, questioning cannot force assent to a cognitive impression to be withdrawn because no argument whose conclusion is the negation of the propositional content of the cognitive impression is valid.

The Academics use the Socratic Method

"We may suppose Arcesilaus putting the question to Zeno, what would happen if the wise man was unable to perceive anything and also it was the mark of the wise man not to form an opinion. Zeno no doubt replied that the wise man's reason for abstaining from forming an opinion would be that there was something that could be perceived. What then was this, asked Arcesilaus. An impression, was doubtless the answer. Then what sort of impression? Hereupon no doubt Zeno defined it as follows, a impression impressed and sealed and moulded from a real object, in conformity with its reality. There followed the further question, did this hold good even if a true impression was of exactly the same form as a false one? At this I imagine Zeno was sharp enough to see that if an impression proceeding from a non-existent thing could be of the same form, there was no impression that could be perceived. Arcesilaus agreed that this addition to the definition was correct, for it was impossible to perceive either a false impression or a true one if a true one had such a character as even a false one might have; but he pressed the points at issue further in order to show that no impression proceeding from a true object is such that a impression proceeding from a false one might not also be of the same form. This is the one argument that has held the field down to the present day" (Academica II.77).

"[The] argument is constructed as follows: 'Some impressions are true, others false; and what is false cannot be perceived [assent does result in cognition]. But a true impression is invariably of such a sort that a false impression also could be of exactly the same sort; and among impressions of such a sort that there is no difference between them, it cannot occur that some are capable of being perceived and others are not. Therefore there is no impression capable of being perceived" (Academica II.40).

"[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 denies that resemblances exist, since they are manifest in ever so many things? But if the fact that many things are like many other things is enough to do away with knowledge, why are you not content with that, especially as we admit it, and why do you prefer to urge a contention utterly excluded by the nature of things.... For it is granted that two twins are alike, ... but you want them to be not alike but downright indiscernible, which is absolutely impossible [because indiscernibles are identical]" (Academica II.54).
In countering the Stoics, the Academics took themselves to follow Socrates.

To investigate the meaning of the Pythia's response to Chaerephon (Apology 20e), Socrates searched for someone with the knowledge necessary to live a good life. Because he was convinced that he lacked this knowledge, he needed a way to determine whether his interlocutors had it. His method was to question them and to use their answers as premises in argument for a conclusion that they themselves thought was contrary to something they believed. If his interlocutors were refuted in this way, it seems that Socrates could conclude that they did not have knowledge and thus that they did not disprove the god.

The Academics use this same method to investigate the Stoics and their "new pronouncements" in epistemology. The Stoics think that it is not necessary to withhold assent from all impressions because some impressions are cognitive, and the Academics test them Socratically with an argument whose conclusion is in conflict with what they think about assent.

In this way, to get the Stoics to agree that they themselves are committed to witholding assent, the Academics press the following argument in questioning against the Stoics:

1.  For every true impression, there is an indistinguishable false impression.
2.  If (1) is true, then no impression is cognitive.
3.  If no impression is cognitive, then it is necessary withhold assent.
4.  It is necessary to withhold assent.

Pressing this argument in questioning againts the Stoics and their epistemology does not prevent the Academics from having beliefs. Nor does it prevent some of their beliefs from being about the force of the argument. The Academics can believe, or even know, that the Stoics should accept the argument and should withhold assent because they insist that assent should be restricted to cognitive impressions and there are no such impressions.

This, though, rises the question of whether the Academics have a consistent position. It cannot be that they themselves assent in terms of cognitive impressions. They must assent in some other way, and it became a problem with the Academy to understand this assent.

Persuasive Impressions

"Carneades holds that there are two classifications of impressions, which under one are divided into those that can be perceived and those that cannot, and under the other into those that are probable (probabilia) and those that are not probable.... [H]is view is that there is no impression of such a sort as to result in perception [no cognitive impression], but many that result in a judgement of probability. For it is contrary to nature for nothing to be probable, and entails that entire subversion of life..." (Academica II.99).

The Greek adjective πιθανόν means "persuasive." Cicero renders it into Latin as probabile, "credible, probable."

"[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 (πιθανὴν φαντασίαν) 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 cross-question each of the witnesses on the testimony of the others,--so likewise, says Carneades, in trivial matters we employ as criterion only the persuasive (πιθανῇ) impression, but in greater matters the irreversible, and in matters which contribute to happiness the tested impression (Sextus Empiricus, Against the Logicians1.184).
Carneades tried to clarify Academic skepticism and its position on assent and belief. He seems to have thought that the Academic can assent to "persuasive" impressions.

In this assent to impressions in terms of their persuasiveness, Carneades seems to have in mind the ordinary way human beings think about things and form beliefs once they have sufficient evidence relative to the importance they attribute to the matter. Unless something intervenes to stop them, human beings ordinarily consider a matter until they have sufficient evidence to decide it one way or another given the importance they attach to it. Once they have this evidence, they ordinarily accept that the issue is as their thinking has shown it to be.

Although Carneades introduced some clarity into the Academic position, it remained unclear why the Academic is permitted to assent to persuasive impressions. The Stoics thought that human beings should assent to cognitive impressions because nature in its providence arranges things so that assent to cognitive impressions results in true beliefs. The Academics do not think there are any cognitive impressions, but they too assent to some impressions. They assent to impressions in terms of their persuasiveness. The question is why this assent is rational.

The evidence is limited, but it appears that Clitomachus and Philo (the subsequent heads of the Academy after Carneades) defend that rationality of Academic assent in different ways.


Clitomachus distinguishes two ways to withhold assent. They are

• to give "absolute assent to no impression at all"
• not "to convey approval or disapproval of something"

According to Clitomachus, the Academic withholds assent in the first way but not in the second. The Academic is "guided by probability" in his "approval" and "disapproval" of impressions. Academic assent is thus a matter of saying 'yes' or 'no' to impressions in such a way that one is simply following his impressions in terms of their persuasiveness.

"For believe [or: to be persuaded (πείθεσθαι)] is said in different ways: sometimes not to resist but simply to follow without any strong impulse or inclination, as the boy is said to believe [or: be persuaded (πείθεσθαι) by] his tutor; but sometimes to assent (συγκατατίθεσθαί) to a thing of by choice and with a kind of sympathy due to strong desire, as when the incontinent man believes [or: is persuaded (πείθεται) by] him who approves of an extravagant mode of life" (Sextus Empiricus, Outlines of Pyrrhonism I.230). "[Clitomachus says] that the formula 'the wise man withholds assent' is used 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; and that this being so, he holds the one plan in theory, so that he never assents, but the other in practice, so that he is guided by probability (probabilitatem), and wherever this [probability] confronts him or is wanting he can answer 'yes' or 'no' accordingly. In fact as we hold that he who restrains himself from assent about all things nevertheless does move and does act, the view is that there remain impressions of a sort that arouse us to action, and also answers that we can give in the affirmative or the negative in reply to questions, merely following a corresponding impression, provided that we answer without actual assent; but that nevertheless not all impressions of this character were actually approved, but those that nothing hindered" (Academica II.104).

Philo of Larisa

It seems that Philo did not describe Academic assent in the way Clitomachus did, as saying 'yes' or 'no' to impressions in such a way that one is following his impressions in terms of their persuasiveness. The problem, though, is that because so little evidence survived, it is not easy to see how Philo understood and defended the rationality of Academic assent.

Cicero is the primary evidence for how Philo understood Academic assent.

"[T]he sole object of our discussions 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 the truth. ... [In this way,] we hold many doctrines as probable (probabilia), which we can easily act upon but can scarcely advance as certain..." (Academica II.7).

"What then is the probability (probabile) that your school [the New Academy] talk about? For if what a particular person happens to encounter, and almost at first glance thinks probable, is accepted as certain, what could be more frivolous than that? While if they assert that they follow an impression after some circumspection and careful consideration, nevertheless they will not find a way out, first because impressions that have no difference between them are all of them equally refused credence; secondly, when they say that it can happen to the wise man that after he has taken every precaution and explored the position most carefully something may yet arise that while appearing to resemble truth (veri simile) is really very far remote from truth, they will be unable to trust themselves, even if they advance at all events a large part of the way, as they are in the habit of saying, towards the actual truth, or indeed come as near to it as possible" (Academica II.36).
"'My view?' replied Catulus, 'I am coming round to the view of my father [Philo's view before his Roman Books], which indeed he used to say was that of Carneades, and am beginning to think that nothing can be perceived [that no impression is cognitive], but to deem that the wise man will assent to something not perceived, 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 that can be comprehended and perceived; and therefore although [in this way] agreeing with their rule of ἐποχήν ["holding back"] as to everything, I assent emphatically to that second view, that nothing exists that can be perceived'" (Academica II.148).

This suggests that Philo thought that the Academic can assent to persuasive impressions. It remains, though, know why Plato thought that this assent is rational.

The answer it not clear at all, but Philo may have thought Academic assent is rational because it is a way to form beliefs that "come as near to [the truth] as possible" (Academica II.36)

This explanation is different from the one Cicero attributes to Clitomachus.

Unike Philo, Clitomachus has no story to tell about about arguments for and against and "resembling the truth" (Academica II.36). Nor presumably does he think that such a story is necessary to reply to the Stoic challenge. The issue is whether the Stoic method of assent in terms of cognitive impressions is better than the Academic method in terms of persuasive impressions. Since to the Academics the assent the Stoics propose appears unusable, it seems that Clitomachus thought that this "new" method is not better than the existing method the Academics use and hence that they will continue to follow their existing practice of saying 'yes' or 'no' to the impressions in terms of their persuasiveness. This is the ordinary way people form beliefs, and the Academics think that the alternative the Stoics propose is not usable.

The Philonian Explanation Prevails

In this dispute with the Academy, the Philo prevailed over the Clitomachians. Otherwise he could not have been elected as head of the Academy, as he was in about 110 BCE.

Why the Philonians prevailed is unclear. To defend Academic assent against the Stoic challenge, the majority thought the Academics must do more than argue against the existence of cognitive impressions in ways that they themselves find persuasive. This, it seems, is what pushed them to accept the Philonian explanation in terms of "resembling the truth."

Pyrrhonian Skepticism

"[T]hey had heard these doctrines from Philo at Rome...." (Academica II.11).
In his "Roman" Books (lectures he gave in Rome), Philo consolidated his position in a way that seemed to narrow the ground between the Academics and their opponents.

"[Philo] maintained that there was nothing that could be grasped (that is the expression that we choose in rendering ἀκατάληπτον ["not graspable, incomprehensible"]), if that 'presentation' of which he spoke (for we have by this time sufficiently habituated ourselves by our yesterday's conversation to this rendering of φαντασίᾳ) was, as Zeno defined it, a presentation impressed and moulded from the object from which it came in a form such as it could not have if it came from an object that was not the one that it actually did come from (we declare that this definition of Zeno's is absolutely correct, for how can anything be grasped in such a way as to make you absolutely confident that it has been perceived and known, if it has a form that could belong to it even if it were false?)--but when Philo weakens and abolishes this, he abolishes the criterion between the unknowable and the knowable; which leads to the inference that nothing can be grasped..." (Academica II.18). The evidence is limited, but Philo seems to argue that although there is no knowledge as the Stoics conceive of knowledge (in terms of assent to a cognitive impression such that no rational means can force its withdraw), the assent permitted to the Academic does result in knowledge if the propositional content of the persuasive impression to which assent is given is true. Under pressure in questioning from someone like Socrates, someone might be convinced by rational means to withdraw assent from a persuasive impression whose propositional content is true. Philo, however, seems to argue that this would not show that he did not have knowledge.

Now, since Philo (in his Roman Books) allows that even members of the Academy can have knowledge, it seemed to some in the Academy that their school had lost its way.

Aenesidemus (1st century BCE) was one of the Academics who thought the Academy had lost its way under Philo's leadership. In about 100 BCE, in an attempt to return to what thought of as the true skepticism that was lost in the Philonian Academy, Aenesidemus founded a breakaway skeptical movement under the name of "Pyrrhonian skepticism."

The Academy ceased to function after Philo's leadership, but the breakaway movement continued in into about the 3rd century CE. Sextus Empiricus is the chief representative. Sextus Empiricus, 2nd or 3rd century CE. He "describe[s] in outline the skeptical doctrine" in his Outlines of Pryrrhonism.

Just what this "skeptical doctrine" is, and how it relates to Clitomachus's understanding of Carneades and the assent to persuasive impressions, is beyond the scope of these lectures.

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 pithanon (probable) and peithestai (to follow; cf. PH [Outlines of Pryrrhonism] I, 230). It is this connection which Cicero tries to preserve when he renders pithanon by probabile to make it correspond to the verb for 'approve' or 'accept' which he likes to use, namely probare (Cic., Ac. pr. [Academica II].99; [Academica II.]139)..." (Michael Frede, "The Skeptic's Two Kinds of Assent and the Question of the Possibility of Knowledge," 215. Essays in Ancient Philosophy, 201-222).

"[Carneades' view, says Clitomachus,] is that there is no impression of such a sort as to result in perception, but many that result in a judgement of probability [or: many that allow for approval (probatio)]" (Academica II.99).
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

"[The Academic reliance on the 'probable'] 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 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 a least a good chance of being true, to be like the truth (versimilis), or else be the truth itself (Cic., Ac. pr. [Academica II] 7; 32; 66; 99; 107). "there is no reason to assume that plausibility and truth, or even evidence and truth, go hand in hand."

I find this part of Frede's interpretation puzzling.
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, and there is no reason to assume that plausibility and truth, or even evidence and truth, go hand in hand" (Michael Frede, "The Skeptic's Two Kinds of Assent and the Question of the Possibility of Knowledge," 213-214. Essays in Ancient Philosophy, 201-222).

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