a Knowledge 34

An impression is an alteration that occurs in the psychē through which something seems to be present or to be the case.168 The Chrysippan account runs as follows:

An impression is an affection occurring in the soul (φαντασία µὲν οὖν ἐστι πάθος ἐν

τῇ ψυχῇ γιγνόµενον), which reveals itself and its cause. Thus, when through sight

we observe something white, the affection is what is engendered in the soul through vision; and it is this affection which enables us to say that there is a white object which activates us. (Aetius, Doxographi Graeci 4.12.1 [=LS 39B])

An impression is thus essentially sentient in nature. Further, in having an impression, the mind produces thought that is linguistically formulable and therefore propositional (“which enables us to say there is”).169 Elsewhere, the relationship of impressions to articulate thought is expressed very clearly: “For impression comes first; then thought, which is capable of expressing itself, puts into the form of a proposition that which the subject receives from a impression.”170 _{However this does not imply that the mind}

receives raw data that it then subsequently interprets. All impressions of rational persons are rational “processes of thought,”171 and all rational impressions may be classified as being either true or false on the basis of the assertions that can be made about them,172 which further accentuates their propositional character. These claims combine to produce a scenario in which the mind’s stock of conceptions is instantly activated upon receiving an impression, such that it presents its object in a

conceptualized form.173

In addition, the Stoics had a specific term for the true impression which was unmistakably trustworthy because it represented its real object with complete accuracy:

167 _{Stobaeus 1.368.12–20 (=LS 53K).} 168 _{Graver, Stoicism, 24.}

169 _{Engberg-Pedersen, Oikeiosis, 147–152, especially 150.}

170 _{Diogenes Laertius 7.49; I translate φαντασία as “impression” instead of “presentation.” See also}

Sextus Empiricus, Math. 8.70 (=LS 33C). For a succinct discussion of the Stoic argument for a linguistic dimension to rationality, see Long, Hellenistic Philosophy, 124–125.

171 _{Diogenes Laertius 7.51.}

172 _{Sextus Empiricus, Math. 7.242–246 (=LS 39G).} 173 _{LS 1.240.}

this was the “cognitive” or “kataleptic” impression (φαντασία καταληπτική)—literally, “impression capable of grasping (its object).”174 Sextus Empiricus reports:

Of true impressions, some are cognitive, others not (τῶν δὲ ἀληθῶν αἱ µέν εἰσι

καταληπτικαὶ αἱ δὲ οὔ). Non-cognitive are ones people experience when they are in

abnormal states. For very large numbers of people who are deranged or melancholic take in an impression which is true but non-cognitive, and arises purely externally and fortuitously, so that they often do not respond to it positively and do not assent to it. A cognitive impression is one which arises from what is (καταληπτικὴ δέ ἐστιν ἡ ἀπὸ ὑπάρχοντος) and is stamped and impressed exactly in accordance with what is, of such a kind as could not arise from what is not . . . For the Stoics say that one who has the cognitive impression fastens on the objective difference of things in a craftsmanlike way, since this kind of impression has a peculiarity which differentiates it from other impressions. (Math. 7.247–252 [=LS 40E])175

As Engberg-Pedersen observes, whether an impression is kataleptic or merely true is a difference of degree with respect to the mind’s contribution. The nature of this

contribution may be elucidated from Sextus’ description of the person having a kataleptic impression as one noticing “in a craftsmanlike way” (τεχνικῶς) the

uniqueness of its properties. The person does this not by having an impression in the sense of an image with some special property that marks it outs as veridical, but by recalling previous knowledge to help him determine what the thing or event is that impinges on his mind. Thus in a kataleptic impression such knowledge is articulated more and more precisely until the description of the thing or event that forms the impression matches exactly that thing or event.176

However, to have an impression—whatever its type—is still simply to entertain a thought, without any implication of commitment to it. Impression is not belief;177 that which transmutes thought into belief is a subsequent mental event called an assent. Specifically, one assents to the unique proposition that is intrinsic to, and the proper object of, any impression.178 _{This implies making a commitment to the veracity or}

desirability of the state of affairs that form the content of an impression, and also having

174 _{See LS 1.250–253, in which there is also a useful summary of the debate between the Stoics and}

the Academics concerning the self-certifiability of such impressions. For the sake of consistency, in my study I shall refer to these impressions as “kataleptic” impressions.

175 _{See also Diogenes Laertius 7.54, who notes that the Stoics regarded the kataleptic impression as}

“the criterion of truth, i.e. the impression arising from what is.”

176 _{Engberg-Pedersen, Oikeiosis, 157–160.}

177 _{See LS 1.239–240, where Long and Sedley helpfully explain that “a Stoic impression in not an}

impression that something is the case—which in modern English, does imply some degree of belief—but just the impression of something’s being the case” (emphases theirs).

the capacity to refrain from doing so.179 Assents can be strong or weak: the wise man’s strong assent is one that is not only firm and certain but is also irreversible, while the weak, less reliable assent of an ordinary person is characterized by precipitancy and changeability.180 In regard to kataleptic impressions, the Stoics assumed that the rational human being was endowed with the mental ability to make accurate discriminations that are congruent with living according to nature. As such, he was therefore naturally predisposed to give his assent to such impressions,181 the outcome of which was “cognition” or katalēpsis (κατάληψις), i.e., assent to a kataleptic impression.182

Drawing together what has been discussed thus far: the Stoic framework for understanding the formation of belief in the human mind has two components:

impression and assent. Any occurrent thought, inclination, desire, or belief that a person may have is necessarily some combination of these two components. In Stoic

epistemology, the highest cognitive state of “knowledge” or “scientific knowledge” (ἐπιστήµη) occurs only when an impression is kataleptic and the corresponding assent is strong. Though katalēpsis is a necessary condition of knowledge, it is not sufficient to constitute it because the cognition has to be impregnable to any thinking that might engender a change of mind. All other combinations of impression and assent produce “opinion” (δόξα), for our sources also tell us that doxa involves weak assent, or assent to what is not kataleptic.183 The Stoic account of these things may be depicted in tabular form, which shows how two kinds of assent, to three kinds of impression, result in six possible types of beliefs (see Table 1).

179 _{LS 1.322; Long and Sedley observe also that Epictetus calls assent “the power to use impressions”}

(Diatr. 1.1.12).

180 _{Stobaeus 2.111.18–112.8 (=LS 41G); Plutarch, St. rep. 1057B (=LS 41F). As Graver, Stoicism, 26,}

expresses it: “The ordinary mind is, as it were, a pushover, yielding easily to impressions which the wise person would resist.”

181 _{Cicero, Acad. 2.30–31, 2.37–38 (=LS 40N). See also Steven K. Strange, “The Stoics on the}

Voluntariness of the Passions,” in Stoicism: Traditions and Transformations, ed. Steven K. Strange and Jack Zupko (Cambridge: Cambridge University Press, 2004), 47–48.

182 _{Cicero, Acad. 1.40–41 (=LS 40B).}

183 _{See e.g. Sextus Empiricus, Math. 7.151–157 (=LS 41C); Cicero, Acad. 1.41–42 (=LS 41B);}

Stobaeus 2.111.18–112.8 (=LS 41G); 2.73.16–74.3 (=LS 41H). Brennan, “Stoic Theory,” 27, notes that as the definition of knowledge is conjunctive, with knowledge and opinion between them exhausting the options, DeMorgan’s laws confirm that opinion’s definition should be disjunctive in this fashion.

Impression

true false

kataleptic merely true

Assent strong knowledge katalēpsis (in the wise) opinion opinion weak opinion katalēpsis (in the non-wise) opinion opinion

Table 1. Impression and Action in the Formation of Belief.184

We should note that knowledge requires a strong assent, and can only be found in the wise person, whose perfected reason contains no inconsistencies. All beliefs found in the non-wise, even if kataleptically true, are merely opinions.