Assent to Persuasive Impressions

Carneades (214-129 BCE), Stanford Encyclopedia of Philosophy


"[T]hat which appears true, and appears so vividly, is the criterion of truth according to Carneades. ... The Academics call these impressions persuasive" (Sextus Empiricus, Against the Logicians I.171).

"[T]he Academic forms his judgement of truth by the concurrence of impressions, and when none of the impressions in the concurrence provokes in him a suspicion of its falsity he asserts that the impression is true. Now in the case of the irreversible impression it is merely required that none of the impressions in the concurrence should disturb us by a suspicion of its falsity but all should be apparently true and not unpersuasive; but in the case of the concurrence which involves the tested impression, we scrutinize attentively each of the impressions in the concurrence" (Sextus Empiricus, Against the Logicians I.178).

"For all these factors together form the criterion—namely, the persuasive impressions, and that which is at once both persuasive and irreversible and besides these that which is at once persuasive and irreversible and tested. And it is because of this that, just 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 impressions, but in greater matters the irreversible, and in matters which contribute to happiness the tested impressions. Moreover, just as they adopt, they say, a different impressions to suit different cases, so also in different circumstances they do not cling to the same impressions. For they declare that they attend to the immediately persuasive in cases where the circumstances do not afford time for an accurate consideration of the matter. A man, for example, is being pursued by enemies, and coming to a ditch he receives a impressions which suggests that there, too, enemies are lying in wait for him; then being carried away by this impressions, as persuasive, he turns aside and avoids the ditch, being led by the persuasiveness of the impressions, before he has exactly ascertained whether or not there really is an ambush of the enemy at the spot. But they follow the persuasive and tested impressions in cases where time is afforded for using their judgement on the object presented with deliberation and thorough examination. For example, on seeing a coil of rope in an unlighted room a man jumps over it, conceiving it for the moment to be a snake, but turning back afterwards he inquires into the truth, and on finding it motionless he is already inclined to think that it is not a snake, but as he reckons, all the same, that snakes too are motionless at times when numbed by winter’s frost, he prods at the coiled mass with a stick, and then, after thus testing the impressions received, he assents to the fact that it is false to suppose that the body presented to him is a snake" (Sextus Empiricus, Against the Logicians I.184).
In dialectic, there is a questioner and a respondent. The questioner tries to get the respondent to contradict himself. In this effort, the questioner is not required to believe the premises he gets the respondent to accept. Nor is he required to believe that the argument he gets the respondent to accept is valid.

At the same time, nothing prevents the questioner from having beliefs. In particular, the rules of dialectic do not prevent the Academics from believing some of the things they try to get the Stoics to accept.

This possibility rises the question of how the Academics understand what they do to form beliefs.

If, for example, the Academics believe that knowledge is impossible, they cannot take themselves to have formed this belief by assenting to a cognitive impression. They must take themselves to do something different.

It was a problem within the Academy to explain in what Academic assent consists and why it is rational.

Carneades (fourth head in succession from Arcesilaus) talked about assent to persuasive impressions.

"These were the arguments which Carneades set forth in detail, in his controversy with the other philosophers, to prove the non-existence of the criterion; yet as he, too, himself requires a criterion for the conduct of life and for the attainment of happiness, he is practically compelled on his own account to frame a theory about it, and to adopt the persuasive impression [as this criterion]" (Sextus Empiricus, Against the Logicians I.166).



Academica II.59

It’s absurd for you to say that you follow persuasive impressions if you are not impeded in any way. First, how can you not be impeded when true and false impressions are not distinct? Second, how can something be the criterion of truth when it is shared by falsehood? These views necessarily spawned the Academics’s ἐποχή, i.e., suspension of assent. Though Arcesilaus was rather more consistent in this, if what some people think about Carneades is true, since if nothing can be perceived—a view both held—we must do away with assent. (What is more pointless than approving something that isn’t known?) But we heard yesterday that Carneades was occasionally liable to sink so low as to say that the wise man would have opinions, i.e., that he would err. In my view, at any rate, it is not as certain that some things are graspable—about which I have now been arguing for too long—as that the wise man will have no opinions, i.e., that he will never assent to anything false or unknown. (59)


Lucullus is the speaker.

As we will see, there was controversy about how to interpret Carneades.

Lucullus says that "we heard yesterday." (He is referring to the now lost Catulus.) What he says they heard was that Carneades said that the wise man can have opinions. Lucullus thinks Carneades is mistaken.

The wise man is someone who is perfectly rational. So the dispute is over what perfect rationality permits. Carneades, as he is being interpreted, thought that perfect rationality is consistent with having opinions. Lucullus advocates the Stoic position that perfect rationality is inconsistent with opinion.

This Stoic position is surprising from our modern point of view.

Lucullus does not say in what context Carneades said that the wise man can have opinions.

It might be that Carneades said this in reply to the inactivity argument. The Stoics pressed this argument against the Academics. The Stoics tried to get the Academics to see that if they believed that knowledge is impossible, then their own beliefs committed them to thinking that rational action is impossible too.

It might, then, have been in reply to this Stoic argument that Carneades said that the wise man can have opinions. He might have replied as part of the dialectic that it was possible to assent to impressions in terms of their persuasiveness and to make the choices we do against the background of our assents to these impressions.

According to Sextus Empiricus, Carneades said that this method of assent in terms of persuasive impressions is the ordinary way human beings form beliefs. They consider something that interests them until they have sufficient evidence to decide it one way or another given the importance they attribute to the matter. Once they have this evidence, they assent and come to believe that the issue is as their thinking has shown it to be.

On this interpretation, Carneades need not be understood to himself believe that the wise man can have opinions. He is arguing dialectically against the Stoics. This does not require him to endorse the arguments he makes. He can be understood as calling attention to a position the Stoics must rule out if they are to hold to their view.

"[Hortensius said] that you should at least admit that the wise person apprehends the claim that nothing is apprehensible. Antipater used to make the same demand: it is still consistent, he maintained, for someone affirming that nothing is apprehensible to say that this one claim is apprehensible though nothing else is. But Carneades resisted him more forcefully, saying that, far from being consistent, it was actually grossly inconsistent: someone claiming that nothing is apprehensible makes no exceptions; it follows necessarily that, since it hasn’t been excepted, the claim itself can’t be apprehensible, either" (Academica II.28). The rules of dialectic, though, do not prevent Carneades from believing that the wise man can have opinions.

Lucullus thinks that what rules this belief out is the Academic "ἐποχή, i.e., suspension of assent." He attributes ἐποχή to Arcesilaus (the founder of the New Academy) and criticizes Carneades for departing from it.



Academica I.45, II.66

That’s why Arcesilaus denied that anything could be known, not even the residual claim Socrates 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 "I am burning with the desire to discover the truth and my arguments express what I really think. How could I not desire to find the truth when I rejoice if I find something truth-like? But just as I judge this, seeing truths, to be the best thing, so approving falsehoods in the place of truths is the worst. Not that I am someone who never accepts anything false, never assents, and never holds an opinion; but we are investigating the wise man. I am actually a great opinion-holder. ... I err or wander farther afield. But it’s not me but the wise man we are investigating. When these impressions strike my mind or senses sharply, I accept them, and sometimes even assent to them (although I don’t perceive them, since I think that nothing can be perceived). I’m not wise, so I yield to these impressions and can’t resist them" (Academica II.65),

Cicero seems to distinguish "accepting" and "assenting" to impressions.

What is the distinction, if any, between "accepting" and "assenting"?

Another puzzle here is that Cicero attributes the greatest importance to possessing true beliefs but seems untroubled that he falls short. He thinks that he should withhold assent because knowledge is impossible, but he seems more than content to assent despite the fact that by the standards he himself announces, his assent is rash and irrational for him to give.

Cicero says that he "yields" to these impressions and "can't resist them."

Why is Cicero unable to resist these impressions?

What is the difference between "yielding," "accepting", and "assenting"?
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 and perception. His practice was consistent with this theory, so that by arguing against everyone’s views he led most of them away from their own: when arguments of equal weight were found for the opposite sides of the same subject, it was easier to withhold assent from either side. (45)

As for the wise man, Arcesilaus agrees with Zeno that his greatest strength is precisely to make sure that he isn’t tricked and see to it that he isn’t deceived. Nothing is farther from the picture we have of the seriousness of the wise person than error, levity, or rashness. So what shall I say about the strength of resistance in the wise man? In fact, Lucullus, you, too, agree that he doesn’t hold any opinions. And since that’s something you approve. (66)


Varro is the speaker in the first passage. Cicero is the speaker in the second.

What Varro says about Arcesilaus is confusing.

Consider the claim that "when arguments of equal weight were found for the opposite sides of the same subject, it was easier to withhold assent from either side." This appears to be an obvious truth about rationality. If the evidence for and against P is balanced, we should believe neither P nor its negation.

Given that this claim about rationality is obvious, why is Varro pointing it out?

It appears that Varro takes Arcesilaus to have believed that the evidence for and against is balanced for every P and to have concluded that therefore it is never rational to assent to any impression.

This is puzzling because the belief seems to make Arcesilaus assent and thus be irrational.

What Cicero says about Arcesilaus is also confusing.

Cicero says that Arcesilaus, Zeno, and Lucullus are in agreement that the wise man has no opinions. The wise man is perfectly rational. He never gives his assent rashly and thus all his beliefs are knowledge.

We can see why Zeno believed this. Zeno and the Stoics think that nature in its providence has arranged things so that we can restrict our assent to cognitive impressions and thus can live the best life a human can live. If we are not living this life, the blame falls on us. We have given our assent rashly and thus have opinions.

Why does Arcesilaus believe that everyone who has opinions has given his assent rashly?

If Arcesilaus believes this because he is irrational, it is hard to see why the Academy had followers.

This suggests that we should think that the position in the Academy was a work in progress. Subsequent heads worked to make it coherent, and their efforts were plausible enough to attract followers.

The timeline for all this (including Cicero's commentary) is roughly as follows.

Zeno founded Stoicism in about 300 BCE. Arcesilaus targeted the Stoic epistemology in dialectic from about 275 to 240 BCE. Chrysippus sharpened ended defended Stoicism in the period roughly from 240 to 210 BCE. From about 170 to 150 BCE, Carneades continued worked to clarify the Academic dialectic against the Stoics. Clitomachus is in the period from about 140 to 110 BCE, and Philo is in the period from about 100 to 88 BCE.

Cicero writes about all this after the the collapse of the Academy and near the end of his life in about 46 to 44 BCE. In the following year, 43 BCE, Cicero died. Julius Caesar had been assassinated in the prior year, and the new regiment murdered Cicero as part of its attempt to eliminate political enemies.



Academica II.78

"Arcesilaus’s position wasn’t widely held at first, despite the prominence he achieved by the sharpness of his intellect and his curiously attractive manner of argument. After him, it was retained by Lacydes alone. Later, however, it was strengthened by Carneades, who was four generations from Arcesilaus (since he was a student of Hegesinus, who was a student of Evandrus, the pupil of Lacydes, who had studied with Arcesilaus). But Carneades maintained the Academic position for a long time—he lived for ninety years—and his students did rather well. Clitomachus was his most industrious student, as the number of his books reveals, but Hagnon was equally remarkable for his intellect, Charmadas for his eloquence, and Melanthius of Rhodes for his charm. (Metrodorus of Stratonicea was also thought to have known Carneades well.) More recently, your teacher Philo worked with Clitomachus for many years; and while Philo lived, the Academy didn’t lack an advocate" (Academica II.16). This is the one disagreement still outstanding. The view that the wise man won’t assent to anything has no part in this controversy: he could fail to perceive anything and yet still have opinions. In fact, this is said to have been the position approved by Carneades—although, since I trust Clitomachus rather than Philo or Metrodorus, I consider it a position that Carneades argued for rather than approved. But let’s put this to one side. It is quite clear that once opinion and perceiving have gone, what follows is the suspension of all assent. Hence, if I show that nothing can be perceived, you must allow that the wise man will never assent (78)


Cicero is the speaker.

This shows that there was some question about how to interpret Carneades and that within the Academy there were two interpretations. One is associated with Clitomachus. The other is associated with Philo and Metrodorus.

Cicero endorses Clitomachus's interpretation of Carneades.



Academica II.108

For my part, I regard standing firm against one’s impressions, fighting off opinions, and restraining one’s assent from slipping as great actions; and 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. (108)


Cicero is the speaker.

Cicero endorses Clitomachus's interpretation of Carneades.

Cicero also has a certain understanding of Clitomachus's interpretation. As Cicero understands him, Clitomachus to takes Carneades to show how we can live without "opinion and rashness."

We need to keep in mind that Cicero might be wrong about Clitomachus's interpretation.



Academica II.112

If I were arguing with a Peripatetic, I would deal straightforwardly with a straightforward person. If he said that an is apprehensible when it is from something true, without adding that significant qualification ‘and stamped in a way it couldn’t be by something false’, I wouldn’t contest this very seriously. And even if his reply to my claim that nothing is graspable was that the wise man would sometimes hold opinions, I wouldn’t rebut his view—especially since even Carneades didn’t fight strongly on this issue.


Cicero is the speaker.

We see again there was uncertainty in the Academy about how to understand Carneades.



Academica II.139

And it’s true that Carneades used to defend Calliphon’s view so enthusiastically that he even seemed to approve it—though Clitomachus affirmed that he never could work out which view had Carneades’ approval. (139)


Cicero is the speaker.

This is in tension with Cicero's previous claim that he thinks Clitomachus is right about Carneades.






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