A Dispute in the Academy
There was a dispute in the Academy about how to interpret Carneades.
He said (in dialectic with the Stoics) that we can assent to impressions in terms of their persuasiveness and that this is what human beings ordinarly do.
It does not follow that this assent is rational.
The Stoics have an explanation for the rationality of their assent in terms of cognitive impressions. They think that nature in its providence arranges things so that this method of assent ensures that we have knowledge we need to live good lives.
What can the Academics say to show the method Carneades identified is rational?
The evidence is extremely limited, but it appears that Clitomachus and Philo (the subsequent heads of the Academy after Carneades) responded in different ways to this question.
Two Ways to Withhold Assent
Cicero provides the evidence for Clitomachus's answer. Clitomachus studied with Carneades, and Cicero says he is quoting from one of Clitomachus's books on withholding assent.
• Academica II.98, II.102, II.104
To make sure that no one suspects that I’m making up what I’m going to say, I will use
citations from Clitomachus—since he worked with Carneades right
up to his old age, and he was a clever man, as you’d expect from a
These books have been lost.
"Clitomachus was a Carthaginian. His real name was Hasdrubal, and he taught philosophy at
Carthage [a Phoenician settlement on the north coast of Africa in present day Tunsia] in
his native tongue [Punic]. He had reached his fortieth year when he went to Athens and became a pupil of Carneades.
And Carneades, recognizing his industry, caused him to be educated and took part in training him. And to
such lengths did his diligence go that he composed more than four hundred treatises. He succeeded
Carneades as head of the school, and by his writings did much to elucidate his opinions"
(Diogenes Laertius Lives of the Philosophers IV.
10).
Carthaginian, as well as a serious and diligent scholar. There are four
books on withholding of assent. (98)
Listen to the way these topics are dealt with by Clitomachus in the book he wrote for the poet Gaius Lucilius (he had already written on the same subjects in a book for Lucius Censorinus, the man who shared the consulship with Manius Manilius). He used pretty much these words—I know them well, because the basic primer, as it were, for the subjects currently at issue is contained in this book. At any rate, the book says this. The Academics hold that there are dissimilarities between things, such that some give rise to persuasive impressions, some don’t. Nevertheless, this is not sufficient reason to claim that some things can be perceived while others cannot, because many false impressions are persuasive, but nothing false can be perceived and known. (102)
After expounding these points, Clitomachus added that this. The wise man is said to withhold assent
in two ways. One when the meaning is that he gives absolute assent to no
"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.
"After setting out these points, he adds 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 presentation
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, and
wherever this confronts him or is wanting he can answer ‘yes’ or ‘no’ accordingly"
(Academica II.104).
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. (104)
Because someone who keeps himself from assenting nevertheless wants to move and act, Clitomachus maintained that there are still impressions of the kind that excite us to action; and likewise, there are still responses we can use when questioned on either side, by just following our impressions on the matter, provided we do so without assent. Yet not all impressions of this kind are approved, but only those that aren’t impeded by anything. (104)
Clitomachus distinguishes two ways to withhold assent from every impression.
One way is to withhold "absolute assent" from every impression.
The other way is to "restrain [one]self from replying" to every impression.
Clitomachus thinks that the wise man withholds assent in the first way but not in the second. He withholds "absolute assent" from every impression he gets, but he does not "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.
What does "absolute assent" mean here?
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 take themselves to do.
What does the Academic take to himself to do?
He tries to do what the "wise man" does.
The wise man does not restrain "himself from replying so as to convey approval or disapproval of something, with the consequence that he neither makes a negation nor an affirmation." Instead, he assents to his impressions in terms of their persuasiveness. If the impression persuasive, he says "yes" to it and is "guided" by its content.
What does "guided" mean here?
One possibility is that to be "guided" by an impression is to believe that its propositional 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.
Truth or its Closest Possible Approximation
The evidence for Philo's response depends on Cicero's understanding of Academic practice.
To be sure, knowledge is always surrounded with
difficulties, and the obscurity of the things themselves and weakness of our
judgments is such that one can see why the earliest and most learned
philosophers lost confidence in their ability to discover what they
desired. Still, they didn’t give up, and we won’t abandon our enthusiasm
"Carneades points out that he will just follow the probable, what
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 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.,
Ac. pr. 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).
Frede's discussion is confusing to understand.
Maybe he means that "on the second interpretation," assenting to persuasive impressions is rational because
"the impression thus arrived at ... has at least a good chance of being true... or else be the truth itself,"
If this is what Frede means, then on what he calls "the other interpretation,"
there is no attempt to explain the rationality of assenting to persuasive impressions
by citing this fact about the connection of the assent to truth.
Frede, however, also seems to say that on this "other interpretation,"
assenting to impressions in terms of their persuasivness is not rational. This method
is just what people use to get impressions "they are willing to rely on."
The Greek adjective πιθανόν means "persuasive." Cicero renders it in Latin as
probabile, "credible, probable."
"[There is] an etymological and conceptual connection between
πιθανόν and πείθεσθαι (to follow; cf.
PH [Outlines of Pryrrhonism] I, 230.
It is this connection
which Cicero tries to preserve when he renders πιθανόν (probable) 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, adjective, "persuasive,
plausible"
πιθανόν is a neuter form of πιθανός
πείθω, verb, "persuade"
πείθεσθαι is a form of πείθω
probo, "approve, esteem, commend"
probare is an infinitive form of probo
probabilis,
"likely, credible, probable"
probabile is a neuter form of probabilis
"For believe (πείθεσθαι)
is said in different ways. Sometimes as not to resist but simply to follow without
strong inclination or adherence, as a boy is said to believe his teacher. Sometimes
as to assent to something by choice and sympathy due to strong desire, as a dissolute man goes along with someone who urges extravagant living."
(Sextus Empiricus, Outlines of Pyrrhonism I.230).
for investigation owing to exhaustion. Nor do our arguments have any
purpose other than to draw out or ‘formulate’ the truth or its closest
possible approximation by means of arguing on either side. (7)
Cicero is the speaker.
He repeats an understanding of Academic practice.
Whose understanding is it?
The two possibilities seem to be Clitomachus and Philo.
In the remarks Cicero says he takes from Clitomachus, the wise man sets the standard. He follows his impressions in terms of their persuasiveness. There is no talk about trying to find "the truth or its closest approximation by means of arguing on either side."
This suggests Cicero's understanding of Academic practice is not Clitomachus's.
Their idea is—and I noticed that you were particularly moved by this—that there are ‘persuasive’ or, as it were, ‘truth-like’ impressions, and this is what they use as their guiding rule both for conducting their lives and in investigation and argument. (32)
Lucullus is the speaker.
He is addressing Cicero as an adherent to the view in the Academy.
What do you mean by your persuasive impressions? If you mean 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. First, because our trust in impressions that don’t differ at all is removed from all of them equally. Second, because 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 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. (35)
Lucullus is the speaker.
He argues that the Academics cannot have "confidence" in their assent in terms of persuasive impressions because such an impression can "be truth-like and yet very far from being true."
Lucullus is working an understanding of Academic practice Cicero repeats.
This understanding of Academic practice does not seem to Clitomachus's. In the words Cicero takes from Clitomachus, he tells no story about about how the method assent Carneades described is rational because it results in beliefs that if not true are at least "truth-like."
To see why, it helps think about the problem the Stoic epistemology poses for the Academy.
The Stoics claim their method of assent is rational. Carneades identified an alternative method in terms of persuasive impressions he claimed is what human beings have been doing all along. The question, then, is whether to give up the ordinary method for the Stoic method.
Since the Academics think there are no cognitive impressions, Clitomachus's answer is that the Stoic method of assent is not better and 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 this method for their new method in terms of cognitive impressions.
The competing answer in terms of the "truth-like" goes beyond this Clitomachian reply to the Stoics. It claims that the method Carneades described is rational because it is a method assent that results in beliefs that are true or at least "like" the truth if they are not true.
This answer is similar to the one the Stoics take to justify their method of assent.
The Stoics think their method of assent is rational because nature in its providence arranges things so that we have the truth if we follow this method. The Academics, as Cicero understands their practice, think the method of assent Carneades described is rational because although it does not always give us the truth, it at least gives us the truth-like.
How could I not desire to find the truth when I rejoice if I find something truth-like. (66)
Cicero is the speaker.
Your wise man also follows persuasive impressions in many cases—i.e., impressions that aren’t grasped, perceived, or assented to, but are truth-like. If he didn’t approve them, his whole life would be undermined. Here’s one case: when he steps into a boat, does the sage grasp in his mind and perceive that he is definitely going to arrive? How could he? Still, should he set out from here to Puteoli, thirty stades away, in a tested vessel, with a good helmsman, and in calm weather like this, he would have the persuasive impression that he will arrive there safely. (99)
Cicero is the speaker.
He is defending the Academic assent to impressions in terms of their persuasiveness. He claims that because the Stoics sage is not omniscient, he will sometimes follow persuasive impressions.
It is unclear that the Stoics themselves think this.
Panaetius (185-110 BCE)
He introduced Stoic doctrines to Rome.
Panaetius (who is pretty much the best of
the Stoics, in my view) says that he has doubts about something that
every other Stoic except him thinks is quite certain, namely, that the
responses of entrail-diviners, auspices, oracles, dreams, and prophecies are true.
So he restrains his assent about this. But if he can do
that even in matters his teachers hold to be certain, why can’t the wise
man do the same in every other case? Is there really any assertion
that the wise man can approve or disapprove but can’t doubt? Do
you really think that you can do this at any stage you like in a sorites
argument, but he can’t come to a similar halt in every other case,
especially when it’s open to him to follow unimpeded truth-like
impressions without assent?
(107)
Cicero is the speaker.
He is replying to the inactivity argument the Stoics pressed against the Academics. He argues that the wise man can "follow unimpeded truth-like impressions."
The process of investigation into the greatest (if also most hidden) matters has its own delight; and if we come across something that strikes us as truth-like, our minds are suffused with a thoroughly humane pleasure. So both your wise man and ours will investigate these questions [about the size of the sun and other such physical matters], but yours to assent, believe, and affirm, ours with the fear of forming rash opinions and the thought that things are going wonderfully for him if he finds something truth-like in questions of this sort. (127)
Cicero is the speaker.
He says that the Academic "fears forming rash opinions."
His point is not very clear.
He might mean that the Academic avoids not opinions themselves but rash opinions because his method of assent results in beliefs that are at least "truth-like" if they are not true.
But what does Catulus think, and Hortensius?
What do I think? I am returning to my father’s view, which he at least said
was Carneades’s. That is, while I don’t think that anything can be perceived,
I still reckon that the wise man will assent to something
he hasn’t perceived—that is, hold opinions—but in such a way
that he understands that it is an opinion and realizes that nothing is
In the Gorgias, Socrates makes similar remarks.
"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).
can be comprehended and perceived. And therefore although I ‡ ... ‡ with their rule of ἐποχή [suspension],
I assent emphatically to that second view that nothing can be perceived.
I’m glad to have your view, Catulus, and I don’t greatly reject it.
But what are your thoughts, Hortensius?
Away with it.
I’m with you, since that’s a view that suits the Academy.
(148)
Cicero asks Catulus and Hortensius what they think.
The text is corrupt. I does not show whether "agree" or "do not agree" is in the original.
Whose view does Catulus express?
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.
A Different Interpretation of the Dispute
Charles Brittain gives a standard interpretation the dispute in the Academy.
LAS = Philo of Larissa: The Last of the Academic Sceptics
OAS = On Academic Scepticism
POL = "Philo of Larissa" (2006)
Brtttain is the author of 2001 Oxford
publication Philo of Larissa: The Last of the Academic Sceptics,
the 2006 Hackett publication On Academic Scepticism, and
the Stanford Encyclopedia of Philosophy entries
on the Academic philosophers
Arcesilaus and
Philo of Larissa.
“The philosophical sense of the
distinction between these two groups [the Clitomachians and the Philonians] has proved difficult to
capture” (LAS, 16). “The manner in which it is held best to spell out this distinction [that defines the
Clitomachian position] is not significant here" (LAS, 75). “It remains very controversial whether there is a
coherent distinction to be made between approving a view [the Clitomachian position] and assenting to its truth [the
position of the Stoics and the Philonians]” (POL). “It is perhaps unclear how we should
(or even can)
make sense of this [Clitomachus’s] position” (OAS, xxvii).
Why, then, is Brittain so sure Clitomachus has this view?
He thinks Cicero understands Clitomachus correctly.
"I believe Clitomachus when he writes
that Carneades had accomplished an almost Herculean labour in that
he had driven assent—i.e., opinion and rashness—from our minds, as
one would drive out a wild and savage monster"
(Academica II.108).
Brittain interprets Cicero to take
Clitomachus to explain how Carneades showed that we can live without beliefs.
If Brittain's interpretation is correct, we still need to know
Cicero did not misunderstand Clitomachus.
Do we know this?
Carneades
set out procedures for assenting to impressions in terms of their persuasiveness, and it might be that
Clitomachus thought this was how Carneades showed
how we can avoid "rashness" in our assent.
This interpretation is consistent with the explanation of the two ways to
withhold assent Cicero says he quotes from Clitomachus's books on withholding assent.
One might object that Cicero is not likely to have misunderstood Clitomachus, but this
must be set against the implausibility of the philosophical view Brittain's interpretation
attributes to Clitomachus.
In this interpretation of the dispute, Brittain sets out two positions. The first is how Clitomachus is supposed to understand
Carneades. Brittain calls Clitomachus's interpretation "radical scepticism." Brittain's second
position is how Philo is supposed to understand Carneades. Brittain calls this interpretation
"mitigated scepticism."
"On the Clitomachian view of Carneades, however, while the Academics will ‘follow’ persuasive impressions, or ‘approve’ them, they will not assent to them: that is the Academics will act on such impressions, without taking them to be true" (LOS, 16).
"[Although] the Academic does not hold dogmatic beliefs asserting the truth of a given proposition, it is open to him to ‘follow’ or ‘approve’ impressions which are ‘persuasive’ to him, in the sense that he may act on such impressions as if they were true without committing himself to their truth" (LOS, 74).
"Clitomachus argued [that] we should distinguish between ‘assenting’ to an impression in the Stoic sense and ‘approving’ it ..., i.e., acting on it as if we took it to be true. The Academic thus gives his approval to the impressions he acts on—he ‘follows’ persuasive impressions—but does not assent to them" (OAS, xxvii).
The view Brittain attributes to Clitomachus is implausible philosophically. This does not mean Clitomachus did not hold it, but it does mean Britain must provide strong evidence.
Clitomachus is supposed to think he "follows" impressions but does not "assent" to them. Brittain thinks that this is what Clitomachus is saying when, as Cicero reports in Academica II.104, he describes how the "wise man is said to withhold assent in two ways."
Brittain understands Clitomachus to think that assenting to an impression is taking its propositional content to be true and to think the wise man does not do this. Instead of forming beliefs by assenting to certain impressions, the wise man only follows these impressions. In doing this, he acts as if the propositional contents of these impressions are true.
This gives Clitomachus an extremely surprising view. We can understand how someone in a play acts as if certain propositions are true, but it is harder to understand how this could be true for every impression someone gets. Someone like this has no beliefs. He does not represent the world as being a certain way and choose his actions by thinking about how what he does will change the world as he understands it. This means he has no mind.
What is "the Stoic sense" Brittain is talking about?
Maybe Brittain means that Clitomachus distinguished between two senses of the Greek counterparts of the word assent. On one sense, it means "commit oneself the truth of the propositional content of the impression." On the other, it means "act as if one commits oneself to the truth of the propositional content of the impression."
The Greek words do not have these senses. This, again, does not mean that Clitomachus did not say that they did, but it does mean Brittain must provide strong evidence.
"[W]hen the Academics draw their notorious conclusions about the unattainability of knowledge and the irrationality of forming beliefs, they are maintaining only that these conclusions are currently ‘persuasive’: they are not committed to the truth of these views or of the arguments that support them. But in that case, the Clitomachian Academics do not believe, e.g., that nothing can be known, or, at least, they do not believe it in the sense implied by Stoic assent. It is perhaps unclear how we should (or even can) make sense of this position, but it is plain that Clitomachus did not subscribe to the form of dogmatic, negative scepticism suggested by his advocacy of [that there are no cognitive impressions and that it is irrational to assent to noncognitive impressions]. For this reason, it is appropriate to call this Academic position ‘radical scepticism'" (OAS, xxvii).
“[On one] definition, a sceptic is someone who positively evaluates abstention from all belief; scepticism in that sense is idiotic” (Harty Field, “Apriority as an Evaluative Notion,” 127. New Essays on the A Priori, 117-149. Oxford University Press, 2000). It is tempting to think that when Brittain says that the view he attributes to the "Clitomachean Academics" is "radical," he is understating the case.
"Clitomachus distinguishes between dogmatic ‘assent’ and the sceptic’s ‘approval’ by identifying two kinds of suspension of assent. The first [is] the refusal to accept that an impression is true (the negative correlative of dogmatic assent). The second kind of suspension of assent is universal: a flat refusal to accept any impression in any way at all. The Clitomachian Academic rejects the second kind of suspension in approving or ‘assenting’ to persuasive impressions; but he continues to suspend assent in the first sense because he acts on persuasive impressions without thereby taking them to be true" (OAS, note 154 on 61).
Now Brittain is talking about "kinds of suspension of assent," not senses of words.
Words have senses. The senses are their meanings.
The word 'cape,' for example, has two senses. It can mean "article of clothing worn over the shoulder" or "strip of land jutting out to sea."
What is the "second kind of suspension of assent"?
It is to suspend assent by not "accept[ing] an impression in any way at all."
"The second position—which [is adopted by Philo and probably Metrodorus] we can call ‘mitigated scepticism’ to distinguish it from Clitomachus’—accepts inapprehensibility, but maintains that it does not follow that we should reject all assent. Hence, these Academics reject the conclusion that it is irrational to assent to anything. But they also characterize the beliefs they do form as ‘opinions’ to mark the fact that, despite their rational grounds for holding them, they are explicitly rational beliefs, i.e., they do not amount to apprehensions. If this is right, the mitigatedly sceptical position is one that advocates forming reasonable beliefs in conditions of uncertainty—and since, in their view, conditions are always uncertain owing to the nonexistence of cataleptic impressions, it also claims that reasonable beliefs are the best we can hope to attain" (OAS, xxvii-xxix).
Philo is supposed to have held what Brittain calls "mitigated scepticism."
The mitigated skeptic assents to impressions. He commits himself to the truth of their propositional contents. This means that the mitigated skeptic has beliefs, and this is a big step away from the radicalness of the radical skepticism Brittain attributes to Clitomachus.
This is another big difference too between radical and mitigated skepticism. The mitigated skeptic thinks that assenting and forming beliefs in certain situations is rational.
"The crucial difference was the change from the purely subjective Clitomachian interpretation of the pithanon--under which πιθανόν there is no inference from what is persuasive to what is true-- to the Philonian/Metrodorians’ quasi-objective use of it as evidence for the truth" (LOS, 16).
“These mitigated skeptics thus took the persuasiveness of perceptual impressions under the right perceptual and coherence conditions as defeasible, but rational, evidence for their truth, rather than as merely the ground for their acceptance" (POL).
"The difference between this position and Clitomachus’ is difficult to discern in practice, because both groups used the same criteria for evaluating impressions and philosophical theses. So both groups use the subjective ‘clarity’ of their perceptual impressions and their coherence with other impressions to grade their degree of ‘persuasiveness,' and both use the Academic method of arguing on either side of philosophical questions to examine which are more ‘persuasive.’ But they differ in that the mitigated sceptics will assent to persuasive impressions or claims when the evidence supporting them is sufficiently strong—and they assume that persuasiveness under the appropriate conditions does provide evidence for the truth" (OAS, xxvii-xxix).
What does Brittain mean with his talk about truth and evidence here?
Here is one possibility.
Clitomachus and Philo did not agree about whether the persuasiveness of an impression is evidence for the truth of its propositional content.
"[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).
Think about what Sextus Empiricus says about Carneades.
In ordinary life, when the question is about a small matter, we are content to take the word of a single witness. Given that the degree of importance we attribute to the matter is small and that we have no reason to be suspicious, we accept the testimony from the witness that such-and-such happened. This makes the impression that such-and-such happened persuasive, but the evidence for the truth of the propositional content of the persuasive impression is not that the impression is persuasive. It is that the witness told us that it happened.
Here is another possibility for what Brittain means.
In the example, it looks like we are making an inference. The impression that the butler stole the money is persuasive for us because we accept the maid's testimony and so conclude that the butler stole the money on basis of our belief that the maid is telling the truth.
Maybe Brittain means that Clitomachus does not think that this inference is rational. Otherwise he would have beliefs, and the Clitomachean Academic only acts as if he has beliefs.
"The Stoics conceived of assent as a unitary notion—to assent to an impression (or proposition) is simply to take it to be true. Clitomachus had identified a non-dogmatic form of assent, ‘following’ or ‘approving’ what is persuasive, where to ‘follow’ what is persuasive’ is to act on an impression as if it were true, but without any commitment to its truth in reality. The Philonian/Metrodorians in turn recognize a third form of assent: provisionally taking the impression to be true" (LOS, 88).
"Philonian/Metrodorian beliefs are provisional in two respects: they incorporate the recognition that they may be false, and they are explicitly related to a body of (subjective) evidence, which in virtue of the thesis of acatalepsia [ἀκαταληψία], is avowedly incomplete. The second feature here explains the first; however strong the conditions on giving one's assent to a belief may be, the possibility of further evidence against the belief remains. The use of the Stoic term 'opinion' by the Philonian/Metrodorians is thus explained by a simple aspect of such beliefs: they are (wittingly) defeasible" (LOS, 87).
The Philonian/Metrodorian, unlike the Clitomachian, believes that his persuasive impressions are true, but he takes these beliefs he forms to be "provisional."
Brittain does not say what "provisional" means.
Here is a possiblity.
Socrates asked his interlocutors some question. When they answered, he asked them further questions to show them they had a reason to withdraw their answer to the first question.
Maybe the Philonian/Metrodorian thinks his beliefs are "provisional" in this way.
"The fact that [mitigated sceptics] take the thesis that nothing can be known to be a paradigm for rational belief or ‘opinion’ itself indicates the depth of their disagreement with more radical sceptics like Clitomachus. Their view implies, after all, that they have bought into the Stoic theories of psychology, impressions, perception, etc., because they think that they have adequate rational grounds to believe that the Stoic definition of apprehension is correct even though its conditions can never be met" (OAS, xxx).
One "provisonal" belief the mitigated skeptic possesses is that knowledge is not possible.
