Stoic epistemology 101: Zeno and the metaphor of the hand movement

(Thanks to Jennifer Lynn Sears [[email protected]] for the idea of this sequence of emoticons. See text for explanation.)

If we don’t understand, at least approximately, how the world works, we are likely to mislive our lives. This was a cardinal assumption of pretty much all the Hellenistic philosophies. The Cynics, the Cyrenaics, the Epicureans, the Skeptics, and the Stoics all thought that we should live “according to nature,” though they cashed out that phrase in different ways. For the Epicureans, for instance, it was in accordance to nature to seek pleasure and, especially, to avoid pain. For the Stoics, following nature meant to take seriously the fact that we are social animals capable of reason. And so forth.

This approach to ethics (understood as the study of how to live one’s life) has two interesting implications: first, a rejection of what in modern philosophy is known as the is/ought gap, famously described by David Hume:

“In every system of morality, which I have hitherto met with, I have always remarked, that the author proceeds for some time in the ordinary way of reasoning, and establishes the being of a God, or makes observations concerning human affairs; when of a sudden I am surprised to find, that instead of the usual copulations of propositions, is, and is not, I meet with no proposition that is not connected with an ought, or an ought not. This change is imperceptible; but is, however, of the last consequence. For as this ought, or ought not, expresses some new relation or affirmation, 'tis necessary that it should be observed and explained; and at the same time that a reason should be given, for what seems altogether inconceivable, how this new relation can be a deduction from others, which are entirely different from it.” (Treatise of Human Nature, section 1, pp. 469-470)

But if you are building a naturalistic ethics, i.e., an ethics grounded in (though not uniquely constrained by) human nature, then there isn’t any sharp distinction between facts and values. This isn’t to say that facts rigidly determine values (I’m going to call this the Sam Harris fallacy), since there will often be more than one reasonable way to interpret any given set of facts. That’s why the Stoics insisted that in order to arrive at a good ethics one ought to study both “physics” (i.e., science and metaphysics) and “logic” (i.e., everything that improves our thinking abilities, including cognitive science). So Hume is right when he says that a (philosophical) account has to be given every time one goes from facts to values. But he is wrong when he says that such an account is “inconceivable.”

The second implication of “living according to nature” is that epistemology, i.e., a theory of knowledge, all of a sudden emerges as an important issue for all of us to consider, as opposed to a rather obscure and technical subfield of philosophy. If living a good life depends on reasoning correctly about the world, then we should be concerned with how, exactly, do we arrive at knowledge, or understanding (which are not necessarily the same thing), of that world.

The Stoics — like the Epicureans — thought that ultimately our knowledge of the world is grounded in our sensorial experience. But they also argued that sensorial experience by itself does not provide us knowledge. One needs to think correctly about what our senses are telling us, i.e., one has to arrive at right judgments about one’s own sensorial experiences. Moreover, they thought that the highest level of understanding of the world requires not just correct judgment, but an understanding grounded into a general model of how the world works — essentially what we would term today a scientific model of the world.

Scott Rubarth wrote a very clear article on Stoic philosophy of mind for the Internet Encyclopedia of Philosophy that includes a discussion (in section 3) of the relevance of Stoic epistemology to Stoic psychology (and, in section 4, to Stoic ethics). Interested readers are strongly encouraged to check out Rubarth’s essay, but here is how he puts the crucial point of concern for our present discussion:

“Although we may entertain and experience all sorts of presentations [phantasiai], we do not necessarily accept or respond to them all. Hence the Stoics held that some phantasiai receive assent and some do not. Assent occurs when the mind accepts a phantasia as true. Assent is also a specifically human activity, that is, it assume the power of reason. Although the truth value of a proposition is binary, true or false, there are various levels of recognizing truth. According to the Stoics, opinion (doxa) is a weak or false belief. The sage avoids opinions by withholding assent when conditions do not permit a clear and certain grasp of the truth of a matter. Some presentations experienced in perceptually ideal circumstances, however, are so clear and distinct that they could only come from a real object; these were said to be kataleptikê (fit to grasp). The kataleptic presentation compels assent by its very clarity and, according to some Stoics, represents the criterion for truth. The mental act of apprehending the truth in this way was called katalepsis which means having a firm epistemic grasp.”

Okay, there is quite a bit of jargon here, but it’s actually helpful. Let’s try to clear things up a bit, I promise it will be worth it.

The impressions (or presentations, as Rubarth calls them) we get from our senses are phantasiai (the root of the English word phantasm, or ghost). They are the raw data of our understanding of the world, but do not constitute understanding by themselves.

Impressions usually come with a preliminary or implied judgment attached to them, which is weak, and sometimes (or often) false. This is what the Stoics referred to as “opinion” (doxa).

But impressions can (and should) be subjected to rational evaluation, to decide whether we should grant or deny assent to them. Even if we do, that does not guarantee that the impressions are thereby true. We may still, in good faith, give assent to false impressions (I’ll give an amusing example in a minute).

A kataleptic impression is one of which the individual can be highly confident, because katalepsis is a special, high grade, kind of assent. It is so strong that we have a really hard time denying it (again, an example coming soon).

Finally, true knowledge requires the ability to fit the specific impression within the broader context of our understanding of the world, and is achievable by the sage, or by the sort of social epistemic effort we call science.

As always, the Stoics presented their complex ideas by way of metaphors. Zeno of Citium — the founder of Stoicism — proposed one based on different positions of one’s hand (see top image, except for the last emoticon, which is close to, but not exactly what Zeno suggested):

“Zeno professed to illustrate this by a piece of action; for when he stretched out his fingers, and showed the palm of his hand, ‘Perception,’ said he, ‘is a thing like this.’ Then, when he had a little closed his fingers, 'Assent is like this.’ Afterwards, when he had completely closed his hand, and held forth his fist, that, he said, was comprehension. From which simile he also gave that state a name which it had not before, and called it κατάληψις [katalepsis]. But when he brought his left hand against his right, and with it took a firm and tight hold of his fist, knowledge, he said, was of that character; and that was what none but a wise man possessed.” (Cicero, Academica II.XLVII)

So the sequence (compare with the hand gestures above) is:

raw impression (perception, including a preliminary judgment leading to opinion) > (reasoned) assent > kataleptic impression (comprehension, understanding) > knowledge

Let’s ground all this in some examples, to bring the theory to bear on real life. Suppose I see an attractive woman (or man, depending on one’s taste) walking across the street from me. My first impression (phantasia) is that she is lovely. My “opinion” (doxa), or preliminary judgment (which may be subconscious, and which is already bundled with the impression) is that it would be lovely to have sex with her. But then my rational faculties kick in and I do what Epictetus suggests we do with all impressions:

“So make a practice at once of saying to every strong impression: ‘An impression is all you are, not the source of the impression.’ Then test and assess it with your criteria, but one primarily: ask, ‘Is this something that is, or is not, in my control?’” (Enchiridion 1.5)

As a result of this challenge to my own impression I decide that no, it would most definitely not be good to have sex with the woman, for a variety of reasons, ranging from the fact that I think that casual sex is demeaning (it uses others an means to my own ends) to the even more relevant fact that I’m about to get married to a woman I love and would never do anything to jeopardize that relationship.

But I had to work on my initial impression in order to arrive at my conclusion. Which means the impression itself was not kataleptic, it didn’t present itself to me as obviously true (or false). An example of a kataleptic impression is again given by Epictetus:

“For what reason do we give our assent to something? Because it appears to us to be the case. If something appears not to be the case, it is impossible for us to give our assent. And why so? Because that is the nature of our mind, that it should agree to things that are true, not accept things that are false, and suspend its judgement with regard to things that are uncertain. What is the proof of that? ‘Form the impression, if you can, that it is night at present.’ That is impossible. ‘Put aside the impression that it is day.’ That is impossible. So whenever anyone assents to what is false, one may be sure that he does not willingly give his assent to falsehood (‘for every mind is deprived of the truth against its will’, as Plato observes), but rather that what is false seemed to him to be true.” (Discourses, I.28.1-5)

Epictetus is making two points here: first, he is providing us with an instance of a kataleptic impression: if you have the impression that it is day outside, that impression strikes you with such force that it is undeniable. (Yes, yes, you could be hallucinating, or an evil neuroscientist may be playing tricks on you, or you could be a brain in a vat. But, seriously, setting aside increasingly bizarre and uninformative thought experiments in philosophy of mind, you get the point, right?)

Second, he uses that example to reiterate Plato’s original point that nobody assents to falsehood on purpose (remember that assenting to something means to be rationally convinced of that something, of course one can pretend for all sorts of instrumental reasons to accept a notion she knows is not actually correct). Plato, and the Stoics, use that conclusion to establish their concept of amathia, the notion that nobody does evil on purpose. But that’s another story.

There is a lovely (though likely apocryphal) story that reminds us of just how difficult it is to actually be confident in one’s impressions, even if they appear to be kataleptic. The Stoic Sphaerus was once the guest of the king, and he was discoursing about impressions, opinions, and katalepsis. The king offered him a plate featuring some lovely looking pomegranates. Sphaerus reached out for the fruit, only to find out that it was made of wax. The king laughed and asked the philosopher how come he had assented to the wrong impression. Without skipping a bit, Sphaerus replied that he only assented to the impression that the fruit looked deliciously edible, not that it actually was. Clever, but the king had indeed made his point. 

A better answer would have been for Sphaerus to reply that he never claimed to be a sage, and only sages — according to the Stoics — have true knowledge. The best the rest of us can do is to be aware of the distinctions illustrated by Zeno’s analogy of the end movements, and constantly try to heed Epictetus’ advice to engage our impressions in critical questioning.

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