Carnéades

Carneades (214–129 bc)

The Greek philosopher Carneades was head of the Academy from 167 to 137 bc. Born in North Africa he migrated to Athens, where he studied logic with the Stoic Diogenes of Babylon; but he was soon seduced by the Academy, to which his allegiance was thereafter lifelong. He was a celebrated figure; and in 155 bc he was sent by Athens to Rome as a political ambassador, where he astounded the youth by his rhetorical powers and outraged their elders by his arguments against justice.

Under Carneades’ direction the Academy remained sceptical. But he enlarged the sceptical armoury – in particular, he deployed sorites arguments against various dogmatic positions. He also broadened the target of sceptical attack: thus he showed an especial interest in ethics, where his ‘division’ of possible ethical theories served later as a standard framework for thought on the subject. But his major innovation concerned the notion of ‘the plausible’ (to pithanon). Even if we cannot determine which appearances are true and which false, we are able to distinguish the plausible from the implausible – and further to distinguish among several grades of plausibility. It is disputed – and it was disputed among his immediate followers – how, if at all, Carneades’ remarks on the plausible are to be reconciled with his scepticism.

 

1 Life

Carneades’ life is ill documented. He was born in 214 bc at Cyrene in North Africa. He moved to Athens where he studied logic with the Stoic Diogenes of Babylon and no doubt also listened to the other leading philosophers of the day. He gravitated to the Academy (see Academy), which was still following the sceptical path laid down by Arcesilaus , and in 167 bc he was chosen as scholarch. The school flourished under his leadership: later authors deemed that he had opened a new phase in its history. Blindness and miserable health obliged him to resign his position in 137; but he continued to philosophize vigorously until his death in 129. And when he died there was an eclipse of the moon.

He was a loud man, and admired even by his opponents for his powerful and persuasive style of argument: he had the irresistible force of a mighty river, the subtlety and resilience of a hunted beast. He lost no argument and left no hearer unmoved. When in 155 bc the Athenians petitioned the Roman Senate for the remission of a fine, they sent three philosophers as ambassadors – Diogenes the Stoic, Critolaus the Peripatetic, and Carneades. At Rome the three men displayed their professional talents to an enthusiastic public. Carneades revealed a particular power to charm and excite – the more so when, on successive days and with equal power, he urged the claims first of justice and then of injustice. Stern Cato hurried business through the Senate and bundled the Greeks off home before they could corrupt the Roman youth.

Like Arcesilaus – and Socrates – before him, Carneades wrote nothing. Several of his pupils took notes on his lectures and wrote memorials of his arguments; and our meagre knowledge of Carneades depends ultimately on these works – all of which are lost. Carneades was persuasive, but he was also elusive; and his pupils disagreed on how to interpret him: his successor Clitomachus, who wrote voluminously about his master, confessed that ‘he could never understand what Carneades believed’ (Cicero, Academics II 139); and Metrodorus claimed that ‘everyone has misunderstood Carneades’ (Philodemus, History of the Academy XXVI 8–10 ).

Also like Arcesilaus – and Socrates – before him, Carneades argued against all-comers, showing himself ‘the most acute and fertile’ proponent of the elenchos or method of refutation (Cicero, Tusculan Disputations V 11). He also argued ‘on both sides’ – notoriously during his ambassadorial visit to Rome. And he was familiar with at least the rudiments of Stoic logic, so that his arguments against the Stoics were often and deliberately expressed as instances of Stoic inference patterns (see Stoicism §11 ).

In addition, he had a weakness for ‘soritical’ arguments – arguments which proceed ‘little by little’ from apparently true premises to an apparently false conclusion (see Vagueness §2). Such arguments were not invented by Carneades. Moreover, they had already been used against the Stoics; for Chrysippus had tried to answer them: before he came to the difficult cases he would ‘fall silent’ (hēsychazein). Carneades thought little of this reply:

As for falling silent, as far as I’m concerned you may snore. What good does it do you? Someone has only to wake you up and pose the same question again.

(Cicero, Academics II 93)

The sorites cannot be slept away (see further Stoicism §11 ).

Like Arcesilaus, Carneades was especially energetic in his attacks on the Stoa: he read Stoic texts assiduously, and confessed that ‘had Chrysippus not existed, I would not have done either’ (Diogenes Laertius IV 62). But his aim extended more widely – we happen to know that he discussed some aspects of Epicureanism; and Sextus Empiricus affirms that ‘with regard to the criterion of truth, Carneades attacked not only the Stoics but all his predecessors’ (Against the Mathematicians VII 159). Moreover, he maintained that, on some issues at least, ‘the dispute between Stoics and Peripatetics concerned not substance but terminology’ (Cicero, On Ends III 41), so that an argument against the former was thereby an argument against the latter (see Antiochus §2 ). It should not be thought (as some have thought) that his philosophy was purely polemical and ad hominem.

Carneades had a particular interest in ethics, where he not only discussed philosophical matters but also composed an idiosyncratic work on consolation. He also reflected on philosophical theology, and on such related issues as divination and the doctrine of fate. But it was primarily for his epistemological attitudes that he was notorious: he argued for some version of scepticism – and at the same time he advocated a ‘criterion’, namely to pithanon or ‘the plausible’. This last item was – or at any rate seemed to some of his disciples to be – a profound innovation; and it was presumably ‘the plausible’ which encouraged the suggestion that Carneades had not merely continued the tradition of Arcesilaus but had instituted a New Academy.

 

2 Ethics

Dogmatic philosophers disagreed over the telos or (Latin) summum bonum, the goal of life or the highest good (see Telos). Carneades catalogued the differing doctrines and incorporated them into a schedule – the ‘division of Carneades’ – which set out ‘not only the opinions on the highest good which have been championed by philosophers up to now but all opinions which can possibly be maintained’ (Cicero, On Ends V 16). The division was celebrated, but no coherent version has survived. Carneades himself urged that the telos is ‘the enjoyment of the goods to which nature first inclines us’ (Cicero, Academics II 131): it is not known how he advocated the view – which in any event he advanced only as part of an ad hominem argument against the Stoics.

On the two Roman speeches on justice we have a little more information. The first speech was an anthology: Carneades ‘put together everything which had been said in favour of justice’ (Lactantius, Divine Institutions V 14.5). On the following day he first distinguished between ‘civil’ justice and ‘natural’ justice. He then urged that civil justice makes good sense: that is to say, it is in the interest of the legislators to enforce the laws which constitute civil justice and which they have conventionally established. But civil ‘justice’ is not just at all. Natural justice, on the other hand, is just – but it is either a phantom or a folly. If the Romans, with their wealth and their conquests, ‘wish to be just, that is, to give back what is not theirs, then they must return to their cottages and live in poverty and misery’. For the community as a whole, natural justice is absurd. And for the individual too. Suppose that you are selling a house which you alone know to be riddled with dry rot: do you show the rot to a prospective purchaser? If you do not, you are prudent – and unjust. If you do, you are just – and foolish. Suppose that you have been shipwrecked and find a fellow sailor clinging weakly to a floating plank: do you dislodge him and grab the plank yourself? If you do, you are prudent – and unjust. If you do not, you are just – and dead.

The second speech, no less than the first, was a cento of familiar arguments and examples. Carneades’ originality lay not in invention but in presentation. What he himself thought of the matter, and what he intended in arguing ‘on both sides’, we cannot tell. But he produced, as Socrates had produced, perplexity and disquiet and hostility. Cato was enraged. (But the Christian Lactantius was pleased; for Carneades had unwittingly shown that pagan philosophy, ignorant of divine truth, had no understanding of the nature and the glory of justice.)

 

3 Theology

Carneades collected arguments against the existence of gods. Some of these mockingly followed Stoic patterns of reasoning. Thus: the gods, being living creatures, must be capable of sense perception; anything which perceives is thereby pleased or displeased; anything which may be displeased may change for the worse; anything which may change for the worse may be destroyed: therefore if there are any gods they can be destroyed. But gods cannot be destroyed. Hence there are no gods. There was also a batch of soritical arguments. Thus:

If Zeus is a god, then Poseidon is a god; if Poseidon is a god, then Achelous is a god; if Achelous is a god, then the Nile is a god;…then streams are gods. But streams are not gods. Therefore Zeus is not a god. But if there were any gods, then Zeus would be one. Hence there are no gods.

(Sextus Empiricus, Against the Mathematicians IX 183)

According to Cicero, ‘Carneades said these things not in order to do away with the gods – what could be less appropriate in a philosopher? – but in order to show that the Stoics explain nothing about the gods’ (On the Nature of the Gods III 44). Perhaps so – in any event, it would be wrong to conclude that Carneades was a convinced atheist; for if even the arguments are not ad hominem – ad Stoicos – they will surely have formed the one half of a set of arguments ‘on both sides’.

Carneades also argued against divine providence, and in particular he disputed the Stoic view that beasts exist for the benefit of mankind – what about bats and scorpions and crocodiles? And he rejected the science of divination (which the Stoics had generally applauded), urging that when a seer gets things right, the success is mere luck. Now divination, according to Carneades, presupposes causal determinism; for ‘even Apollo cannot foretell an event unless there are causes in nature which so constrain it that it is necessary for it to occur’ (Cicero, On Fate 32 ).

The Stoics, who defended divination, held that everything does depend on such naturally necessitating causes – such was their doctrine of fate (see Stoicism §20 ). The doctrine had been variously attacked. Carneades allowed that some of the arguments used against it were fallacious: they falsely conflated the thought that an event is causally determined with the thought that someone may have truly said in advance that it will occur. (To say truly that something will happen is not the same as to divine or foretell it.) And he produced a better argument:

If everything comes about by antecedent causes… then necessity determines everything; if so, then nothing is in our power. Now some things are in our power. But if everything comes about by fate, then everything comes about by antecedent causes. Therefore not everything which comes about comes about by fate.

(Cicero, On Fate 31)

The Epicureans also rejected fatalism. In doing so they introduced their celebrated theory of ‘atomic swerves’ (see Epicureanism §12 ): atoms may suddenly, and for no cause, change trajectory; and these swerves ensure that there may be ‘voluntary motions of the mind’ which leave some actions in our power. But Carneades criticised the Epicureans no less than the Stoics, maintaining (truly enough) that voluntary motion can be better defended than by the introduction of uncaused swerves.

 

4 Scepticism

Carneades and Clitomachus and all their friends trample on the doctrines of everyone else and themselves expressly affirm that everything is inapprehensible and that a false appearance always neighbours a true one.

(Hermias, Mockery of the Pagan Philosophers 15)

According to Carneades, we can apprehend nothing – not even (as Cicero adds) that we can apprehend nothing; for next to and indistinguishable from any true appearance there will always be found a false appearance.

Carneades fired broadsides against every philosophical attempt to provide a criterion of truth. He peppered them with bent oars and round towers and moving coastlines – with all the ‘illusions’ which have diverted later sceptics. In particular, he reflected on the reigning Stoic account of knowledge, which turned on the notion of an ‘apprehensive appearance’ (phantasia katalēptikē) (see Stoicism §12 ).

An appearance (phantasia), being the origin of cognition in animals, ought, like light, both to reveal itself and to indicate the evident item which produces it.

But phantasiai, like unreliable messengers, do not always report correctly the information with which they are charged. What is more, even if a phantasia does manage to give a correct report,

none is true in such a way that it could not be false; rather, for any phantasia which is thought to be true, a false phantasia indistinguishable from it (aparallaktos) can be found.

(Sextus Empiricus, Against the Mathematicians VII 163–4 )

He offered numerous proofs and illustrations of this indistinguishability. Consider the twins, Castor and Pollux: it looks to me for all the world as though Castor is sitting opposite me at the dining table – and indeed he is sitting there. But is this appearance apprehensive, does it give me knowledge that Castor is there? No – for an indistinguishable appearance would have been caused by his twin, Pollux.

In general, if you know something, you must have apprehended it; apprehension is assent to an apprehensive appearance; and an appearance of something is apprehensive if it is true of that thing, if it was caused by that thing, and if it could not have been produced by anything else (see Stoicism §12 ). Like Arcesilaus, Carneades fastened on to the third condition:

They say that they reject this one element, that something true can appear in such a way that what is false could not appear in the same way.

(Cicero, Academics II 33)

If an appearance is apprehensive, then were it not the case that so-and-so it could not seem to me that so-and-so. But this is never so: it could seem to me that Castor was sitting opposite me even if (say) not he but Pollux were there. No appearances are apprehensive. Nothing is known.

Thus far, destruction. But there is also an apparently positive side to Carneades’ scepticism. Alongside the distinction between true and false appearances there is a second and independent distinction between ‘plausible’ (pithanos) and implausible opinions. (The word pithanos was often Latinized as probabilis and hence rendered in English as ‘probable’; but ‘probable’, in its modern sense, is a false translation of pithanos.) Truth and falsity are determined by the relation of an appearance to the items of which it is an appearance. Plausibility and implausibility are determined by the relation of an appearance to the item to whom it appears. An appearance is plausible if it tends to persuade or to evoke assent: it looks to me as if there is a coil of rope in the potting-shed – and the appearance is plausible in so far as I find myself inclined to accept that there is a coil of rope there.

What is plausible for me may not be plausible for you. And there are degrees of plausibility, some appearances being more persuasive than others. Moreover, we may scrutinize our appearances. Perhaps it is really a snake, not a coil of rope? I prod about in the potting-shed with a stick: nothing budges – and I now have a ‘scrutinized’ plausible appearance of a coil of rope. Again, appearances do not come to us as isolated atoms: they arrive in molecules, so that a plausible appearance may be controverted or uncontroverted by its associates. There seem to be no sloughed skins in the shed, I see no notice urging me to Beware of Serpents in the Grass, and so on. None of the other appearances associated with the appearance of the coil of rope controverts that appearance: I have an ‘uncontroverted and scrutinized’ plausible appearance of a coil of rope.

Plausible appearances, however well scrutinized and however uncontroverted, may always be false. None the less, we shall prefer the plausible to the implausible, the more plausible to the less plausible, and the uncontroverted and scrutinized plausible to anything else.

Such is Carneades’ account of plausibility: herein appeared to lie his chief innovation – on account of which his ‘New’ Academy was later distinguished from the Middle Academy of Arcesilaus. What was the philosophical role and function of the account? The problem is this: on the one hand, the plausible, of which Carneades seems to approve, is that which evokes assent; on the other hand, Carneades apparently argues for a scepticism which repudiates any act of assent. Carneades’ own pupils were puzzled, and interpreters have found no solution which commands general agreement.

One of Carneades’ pupils probably construed the theory of plausibility as a theory of knowledge. Carneades’ destructive arguments proved that the standard account of knowledge was flawed. Hence he had to devise another account – and the theory of the plausible lay at its heart. Carneades was not a sceptic – on the contrary, the point of the pithanon pricks the bubble of scepticism (see Philo of Larissa §2 ). Later, St Augustine (on what authority is uncertain) affirmed that Carneades had never intended to attack ‘ordinary’ knowledge: his sceptical assault was limited to philosophical knowledge; and the theory of plausibility offered an account of our ordinary knowledge of ordinary things.

Or perhaps plausibility offers not knowledge but a knowledge substitute. We cannot strictly know anything – but that is no reason to suspend judgement, nor does it imply that all appearances are on an equal footing. Plausibility provides a criterion for rational belief – and rational belief is all we have on earth and all we need to have.

Sextus Empiricus presents Carneades’ ‘plausible’ as a criterion of action: it is concerned with ‘the discrimination of what is good and what is bad’ (Outlines of Pyrrhonism I 226). Carneades suggests not that it is rational to believe what is plausible but that it is rational to act on what is plausible. (And rationality will recommend satisfaction with different degrees and types of plausibility in different practical circumstances.)

Or does the plausible play a purely descriptive and explanatory role? The question to which the plausible offers an answer is perhaps not ‘How should a sceptic act?’ but rather ‘How can a sceptic act?’ Dogmatists argued that without beliefs a sceptic could never stay alive (see Arcesilaus §2 ). But according to Carneades, a sceptic’s actions may be determined by the appearances; for not all appearances are equally plausible – and a sceptic will be moved by the most plausible appearance. Not, of course, that a sceptic will believe the appearance to be true: the appearance evokes ‘assent’ merely insofar as it is acted upon.

These brief suggestions do not exhaust the gamut of interpretations; and the surviving texts scarcely allow a rational choice among them: only in the Elysian fields – if anywhere – shall we learn the truth about Carneades.