Stoicism

12. Cognitive certainty

The main Stoic epistemological theorist was Zeno of Citium, who developed his ideas in response to a series of challenges from the Academic sceptic Arcesilaus (see Arcesilaus §2). His key term is katalēpsis – ‘apprehension’ or ‘cognition’ – the infallible grasping of some truth, usually by use of the senses. Arcesilaus systematically questioned the grounding of this notion, and argued instead for akatalēpsia, ‘inapprehensibility’, or ‘the impossibility of cognition’.

The starting notion is phantasia, literally ‘appearance’ but commonly translated as ‘impression’ or ‘presentation’. To have an impression is simply for things to strike you as being a certain way. Whether or not you take the impression to be true depends on a further cognitive act, assent (synkatathesis), which you may give or withhold at will. Since mature human beings are rational, their impressions are called ‘rational impressions’, meaning that their content can be expressed in language. Strictly speaking it is the proposition associated with it that we are taking to be true when we assent to an impression.

Zeno symbolized an impression by spreading the fingers of one hand, and assent by pulling them together. The next stage, represented by a fist, was katalēpsis, literally ‘grasping’, that is, infallibly recognizing the truth. This is not so much successive to assent as an ideally successful way of assenting, based on a sufficiently lucid impression. If instead someone assents to an unreliable impression, that will not count as cognition, but as mere fallible ‘opinion’ (doxa).

One final stage in the hand simile is epistēmē, ‘knowledge’ – not everyday knowing (which is better identified with katalēpsis) but absolute, scientific knowledge, such as is possessed only by the wise. Zeno symbolized epistēmē by bringing the other hand over to grasp his fist firmly. The point is as follows. Katalēpsis is infallible, in that it successfully applies a simple guaranteed cognitive mechanism shared by virtually all human beings: the truth stares you in the face, and you assent to it without the slightest possibility of being wrong. However, although on this very ordinary model of knowing all of us know lots of things, only the genuinely wise know that they know. This is because the wise, having a complete set of mutually supporting cognitions, could never be argued into disbelieving one of them. The unwise, that is, most people, could be argued out of their assent to genuine cognitions, because they are likely to have also a number of false beliefs, adopted as if they were genuine cognitions. You may, for example, plainly witness a miracle but disbelieve it because, being an Epicurean sympathizer, you falsely believe that the gods do not intervene.

The interest of the Stoic–Academic debate lies largely in its concentration, not on the wise, but on the infallible cognition attributed to ordinary people. The Stoics remained convinced, perhaps like most of us, that in everyday encounters where the truth stares you in the face you cannot be wrong and would be insane to withhold assent. But this common-sense position proved extraordinarily vulnerable to Academic criticism.

Debate centred on the kind of impression to which assent might be fully justified. Zeno called this the phantasia katalēptikē, ‘cognitive impression’, and initially defined it as one which is ‘(i) from something real (apo hyparchontos), and (ii) moulded and impressed according to that real thing itself’. Here (i) is likely to mean, not ‘caused by something real’ (no impression, however delusory, could be either caused by something unreal or totally uncaused), but ‘representing something actual’ – where it is indifferent whether the thing represented is an object or a fact. What (ii) adds is that the impression depicts this thing in full graphic detail. Arcesilaus’ complaint was that such an impression would still not be unmistakably true, since an identical but false impression could occur. This led Zeno to add a third clause, ‘(iii) such as could not be from something unreal’, which we can take to mean ‘such as could not represent some non-actual object or fact’.

The problem now was whether there could be such an impression. The ensuing debate focused partly on the nature of external objects, with the Stoics asserting that each object – even an identical twin – has some unique feature (see §6 for the metaphysical justification of this), and the Academics asking in reply how we could ever be sure that the relevant feature was currently evident. The Stoics also tried to describe the phenomenological features of these cognitive impressions, suggesting that as a species of impression they somehow carried their own badge of identity ‘just as horned snakes differ from other snakes’. The Academic reply, now through the mouth of Carneades, included appeal to cases where false impressions are so graphic that they lead to action, exactly as allegedly cognitive ones do: can the latter then have any intrinsic features to differentiate them from the former?

The final word belongs to a group reported simply as the ‘later Stoics’ (Sextus Empiricus, Against the Professors VII 253–60), probably including Antipater, a contemporary of Carneades. They point out that in all but the most special circumstances we simply have no choice whether to assent to a cognitive impression. Once you have such an impression, you do believe it, and that is that. What is in our own hands is not whether, once we are in a position where the truth is unmistakable, we accept it, but whether we take the trouble to get ourselves into such a position in the first place (moving closer, turning on the light, and so on).

This is quite an effective reply to those, like the Academics, who recommend suspending assent. But it leaves the question why the irresistibility of certain impressions should imply their truth. The Stoics here had recourse to a teleological argument: we would not have been given this superb cognitive equipment for any other purpose than to learn the truth. But of course the Academics could easily question the empirical premises on which that teleology was founded, bringing the debate full circle.