3 GREEK PHILOSOPHY AND SIGNS

JAMES ALLEN, UNIVERSITY OF PITTSBURGH

1

Our term “sign” comes, of course, straight from the Latin signum, which in turn renders the Greek appetOV, whose range of uses it tracks pretty closely.

2

As a first approximation, we might say that a sign is something that has or conveys mean­ing. This proposal is on the right lines, but baldly stated it has the potential to mislead. Talk of “meaning” inevitably brings to mind words, statements, and the like — in a word, language or language-like communication devices such as coded messages or signals.

It is not that we do not find the ancient term “sign” and the verb “signify” employed in this way. This use is well and amply attested. Plato’s Cratylus was the most sustained and influential contribution to the long-running ancient debate about whether word-meaning is simply a matter of convention or there is, rather, a natural standard of correctness that gov­erns the relation between words and their meanings so that some words are better suited by nature to mean certain things than others.

Yet another use of “sign” is at least as common. “Smoke is a sign of fire.” “Tracks of this kind are a sign that a leopard has passed this way.” “The fact that there is a ring around the moon is a sign that it will rain tomorrow.” In cases like these there is, it seems, no question of anyone meaning something by the signs at issue. They serve, instead, as evidence or grounds for a conclusion — and this appears to be a very different thing indeed. Yet here too, even in the absence of someone who means something, we still speak of meaning. “The fact that there is a ring around the moon means that it will rain tomorrow,” “Smoke means fire,” and so on. These facts are the basis of the distinction between natural and non-natural meaning drawn in a celebrated article by H. P. Grice, who was himself looking back to a distinction of Saint Augustine’s between natural and given signs (signa naturalia, signa data).¹ Very roughly speaking, natural meaning, which belongs to natural signs as such, is the evidential support that a sign furnishes for a conclusion, while given signs are used by humans, or be­ings relevantly like them, in order to convey their thoughts to other such beings, where it is somehow essential if this task is to be effected that the recipient grasp that this is the intention of the sign’s user.^{2 *}

The fact that the word “meaning,” with its very different history, also extends across the divide separating the natural from the non-natural or given divide suggests that it is not an accident that the same term “sign” comes to be used of these very different cases.

3

For the present, however, I shall concentrate on the natural side of the divide. A (natural) sign furnishes evidence: when all goes well, we come to know something distinct from it by inferring a conclusion from it. To discharge this function, it is not enough that the sign furnish grounds for the conclusion at issue, it must be better or more easily known than it, either in general or on the occasion of its use as a sign. This condition is enshrined in the requirement that a sign be revelatory, which is part of the Stoic definition of the sign as “a true antecedent in a sound conditional revelatory of the consequent.”³ So, for example, though the fact that

it is light follows from the fact that is it day, the latter can hardly be a sign of the former. One cannot know that it is day without, at the same time, knowing that it is light. Compare the familiar examples cited earlier: smoke as a sign of fire, tracks as the sign of an animal’s passage, and the like. Knowledge of the sign is, so to speak, given to us directly, while that of which it is a sign comes to be known through the sign.

The ancient Greek ένάργεια and Latin evidentia mean the quality of being evident or manifest, which I believe remains the dominant sense of “evidence” in modern European languages apart from English. To serve as evidence for or of a conclusion, a sign must exhibit evidence in this sense in addition to furnishing grounds for a conclusion, either absolutely or by comparison with the conclusion for which it is evidence, which fact seems to lie behind the sense of the term meaning evidence for a conclusion.

There is another pervasive, if not completely ubiquitous, feature of the ancient Greek philosophical thought about signs that calls for comment. Inference from signs often, though not always, makes up the inferior side of a contrast with forms of inference, sometimes called “demonstrations” (άπό δέϊξίς), that are, in one way or another, superior to it. The version of this contrast that we find in Aristotle, where for the most part it is implicit, is representative. According to him, one has knowledge, at least in the strict and favored sense, not when one has a true belief and is justified in holding it — the condition that we tend to mean when we speak of knowledge and the focus of most contemporary epistemology — but rather when, in addition, one understands why matters are as one knows them to be, that is, grasps the cause or explanation for their being so. This is knowing the because as opposed to knowing (merely) the that, as Aristotle often puts it, and it is this condition that deserves above all to be called knowledge in his view.

The first principles of a science, in terms of which everything in the domain of that science is to be explained, are themselves self-explanatory, not by being self-evident, but in the sense that, while other things are explained and understood by reference to them, they are not un­derstood or explained by reference to other more fundamental principles. When he is adhering strictly to his own technical terminology, Aristotle calls our grasp of them not “knowledge” (έπιστημη) but νους, “intuition” or however else we choose to translate this elusive term. Knowledge or έπιστημη, most properly so called, is confined to derivative truths, which one must grasp as consequences of the first principles by which they are necessitated and explained if one is to know them in this favored sense. According to Aristotle, this condition consists in the grasp of an argument or syllogism of a special kind, viz., a demonstration, which in turn is defined as a syllogism by grasping which we know (Nicomachean Ethics 6.3, 1139b31-2; Analytica posteriora 1.2, 71b18).

Consider a favorite example of his: the demonstration that the planets do not twinkle (Analytica posteriora 1.13, 78a30-b4). Not-twinkling belongs to all that is near, nearness belongs to the planets; therefore the planets do not twinkle. Those familiar with Aristotelian logic will recognize this as a categorical syllogism in the first figure mood, Barbara. A crucial feature of a demonstration, according to Aristotle, is that the so-called middle term, in this case nearness, state the cause or explanation. It is because the planets are near that they do not twinkle, and it is, therefore, by grasping this syllogism that one understands why the planets do not twinkle at the same time as one grasps that they do not.

But suppose, says Aristotle, that the premise stating that not-twinkling belongs to all that is near converts, that is, not only does not-twinkling belong to everything that is near but near­ness belongs to everything that does not twinkle. In these conditions, it is possible to construct an argument, also a syllogism in Barbara, that deduces the conclusion that the planets are near, one of the premises of the demonstration above, from the converted proposition, everything that does not twinkle is near, together with the fact, which can be established by observation, that the planets do not twinkle. Though the argument is no less valid and its premises and conclusion no less true, it is not a demonstration, strictly speaking, since the conclusion is not explained by the premises. The middle term, not-twinkling in this case, is not the cause; that is, it is not because the planets do not twinkle that they are near, though it is because they do not twinkle that, when guided by this argument, we are justified in concluding that they are near. In old-fashioned terms, not twinkling is the ratio cognoscendi not the ratio essendid

But though not the cause, not-twinkling is evidence for the nearness of the planets or, alternatively, a sign of their being near.

Thus in Aristotle’s hands talk of signs often signals a contrast between inferences that put us in a position to know the that and inferences that lay bare the causes thereby enabling us to understand the why. Signs are, if you will, mere evidence. Indeed the few remarks that Aristotle devotes explicitly to sign-inference are in passages concerned with forms of argu­ment that are most prominent in rhetoric, where the object is not a deeper understanding of the kind sought in the sciences, but the simple establishing of the facts (Analytica priora 2.27; Rhetorica 1.2, 1357a33ff.; 2.25, 1402b12ff.).^[8]

4

Two observations should be made before we proceed. First, some ancient philosophers, especially but not only the pre-Socratics, were happy to speak of signs in connection with inferences by means of which the sciences are constituted and an understanding of the ultimate causes at work in nature secured (if not quite in the Aristotelian way). This seems often to coincide with a tendency not to draw the kind of distinctions between types of inference and types of ground that we have been considering, or at least not to assign it a place of such cen­tral importance. Epicurus is an example, about whom I shall have more to say soon. Second, for those who do make the distinction, experience (epnetpia, experientia) is an especially fruitful source of sign-inferences of the less exalted sort.

Since at least the time of Plato and Aristotle, experience was conceived in something like the following way. It arises out of repeated episodes of perception and is confined to the objects that fall under perception, which are, if you will, inferentially brute or discrete: by themselves and as such, they imply nothing substantively different from their own existence. Nevertheless, observation of recurring patterns of sequence and conjunction among such ob­jects furnishes us with a stock of empirical generalizations, which are of great value not least in supporting sign-inferences like that from smoke to fire.

⁴ Compare Patzig 1981.

According to the view in question, however, no amount of experience by itself is suf­ficient to uncover the underlying natures of things because of which they behave as they are observed to do; these natures are the causes in terms of which genuine explanations must be framed, and they can be revealed, if at all, only by the insights of a special faculty of reason. Plato, Aristotle and those who follow them on this point insist that a real art (τέχνη) and real knowledge (έπτστημη) must go beyond experience to grasp the causes with the aid of reason conceived in this special way. The other distinction with which we shall be chiefly concerned is that between reason and experience.

5

These facts need to be kept in view as we turn to what is far and away the most extensive discussion of signs in surviving ancient Greek philosophical literature, that found in Sextus Empiricus, who was a Pyrrhonian Sceptic active, probably, in late second century A.D. His task as a sceptic was to call into question pretensions to knowledge in each department of philosophy. To this end, he adopts a framework dividing philosophy into parts, within which he expounds in enormous and enormously valuable detail the views of his dogmatic opponents before undertaking to refute them. He tackles epistemology first (which belongs to the logical division of philosophy as the ancient Greeks conceived it), and he treats as common ground a division of labor between the criterion, on the one hand, and signs and proofs on the other (Adversus mathematicos 7.24-26, cf. 396; 8.140, 319; Outlines of Pyrrhonism 2.96).

Knowledge of evident matters is the province of the criterion according to the framework that he adopts, and the truths won with its aid are in turn the basis of inferences by signs or demonstrations that promise to extend knowledge to the realm of the non-evident. It is plain that in setting up this framework Sextus does not distinguish between the function of signs and that of demonstrations and that he assigns to both an elevated part in the formation of natural philosophical theory.

The views that Sextus goes on to present and examine when he turns to signs do not really fulfill the corresponding expectation, however, and this is only the first in a series of peculiari­ties in his account. His discussion is framed in terms of a distinction between commemora­tive and indicative signs, only the former of which, he says, are acceptable to the Pyrrhonists (Outlines of Pyrrhonism 2.200-01; cf. Adversus mathematicos 8.154).

A commemorative sign is: “that which, having been evidently co-observed with the signified, together with its occurrence when the signified matter is non-evident, leads us into a recollection of what was co-observed with it but is now not manifest.”

An indicative sign is: “that which has not been evidently co-observed with the signi­fied, but from its own nature and constitution signifies that of which it is a sign.”

Though this distinction is philosophical in the sense of being concerned with episte­mological issues of completely general import, there are good reasons to believe that it was not the creation of professional philosophers, but rather had its origin in the context of the long-running debate between the self-styled Empirical school of medicine, which arose in the mid-third century B.C., and its opponents, the medical rationalists.^[9]

The Empiricists accepted the challenge laid down by Plato and Aristotle and undertook to show that experience was entirely sufficient to give rise to an art by itself without the aid of reason in the special sense in which it refers to a faculty whose distinctive characteristic is the ability to grasp truths not accessible to observation. Rationalism, on the other hand, was not a single school, but a tendency common to medical thinkers of diverse views belonging to different schools who were united only by the conviction that a true art must go beyond experience and grasp the hidden natures and causes of things by means of reason.

The commemorative sign was, it seems, the favored tool of the Empiricists; the indicative sign that of the rationalists. Both seem to have their home in the practice of an art rather than the original process of constituting one. Commemorative signs point to evident events and conditions with which they have been conjoined in past experience. In the sphere of medicine, indicative signs reveal the hidden, pathological conditions underlying the patient’s symptoms, which in turn indicate the appropriate therapy. To be sure, indicative signs could perhaps be viewed as playing a double role, as the means by which theory is applied to particular cases in practice and as the means by which elements in the theory are inferred from evident observa­tion in the first place, which would make for closer fit with Sextus’ framework. There is little evidence for this, however.

Let me mention two more important oddities. If there was a position that does meet the expectations created by Sextus’ framework, it would seem to be that of Epicurus and his fol­lowers, who make explicit appeals to signs as the basis of their theories about non-evident matters in the realm of natural philosophy, atoms, and the motions of distant heavenly bodies, for instance. But though he mentions Epicurus a couple of times in passing, Sextus has nothing substantive to say about Epicurean views (Adversus mathematicos 8.177, 185).

On the other hand, he devotes much attention to the Stoics, whose definition of the sign I cited above. But this turns out to be perhaps the most puzzling thing of all in Sextus’ treat­ment of signs. He has, as we have seen, no complaint against the commemorative sign and promises to direct his fire exclusively on indicative signification. The Stoic theory against which he argues should then be a theory of indicative signification, or at least have its primary application to indicative signs whether the Stoics used this terminology or not. And indeed the text of Sextus plainly states that the Stoic definition is merely an alternative characterization of the indicative sign (Outlines of Pyrrhonism 2.102). So awkward is the placement of this assertion, and so poorly does it fit its context, however, that scholars, including the editor of the standard edition, have rejected it as an interpolation. If this is right, as there is good reason to believe that it is, what we have is an ill-fated effort to paper over a gap between Sextus’ avowed purpose to combat the indicative sign and the prominence he gives to the case against a Stoic theory whose relation to indicative signs is the opposite of clear.

6

Indeed, such evidence as we have points to a closer affinity with empirical reasoning of the kind that falls under the head of commemorative signification. Unlike the Empiricists, the Stoics did not question the possibility of grasping the hidden natures of things or reject causal explanations based on them. Indeed Sextus also preserves a Stoic theory of demonstra­tion whose chief application appears to have been causal explanation in natural philosophy, which is accorded its own discussion by Sextus (Outlines of Pyrrhonism 2.134-92; Adversus mathematicos 8. 199-481).^[10] But the Stoics seem to have supposed that we are in a position to grasp the causes far less often than many rationalists supposed. Thus Chrysippus (ca. 280-207 B.C.), the third scholarch of the Stoa and the philosopher most responsible for working out the orthodox Stoic position in detail, urges us to rely on experience and history — terms that figure prominently in the Empiricists’ own self-description — in those all too frequent cases where causal speculation is likely to lead us into error (Plutarch, De Stoicorum repugnantiis 1047c). And Posidonius (ca. 135-50 B.C.), the most prominent Stoic of his time, could be faulted by other Stoics for aetiologizing in the Aristotelian manner rather than preserving a more authenti­cally Stoic reserve before the hiddeness (entKpVYtg) of the causes (Strabo 2.3.8).

As it happens, there is a Stoic discipline occupied with signs whose method was in good part empirical, namely divination, about which we know a good deal owing to Cicero’s inter­est (106-43 B.C.). He tackled the subject in his work De divinatione where, proceeding as an Academic skeptic, he expounds the Stoic view before undertaking to refute it.⁸ In a way that should sound very familiar by now, he distinguishes knowledge that, which is obtained through signs, from knowledge of causes, which, to be sure, when complete, would make it possible to know the future in every particular, but which, in this form, is available only to a god (De divinatione 1.127; cf. 12, 16, 29, 35, 86, 109). Much of the time, then, human beings are obliged to fall back on signs.

They are greatly helped by the fact that the signs in question were fashioned by divine providence for the benefit of humankind. According the Stoics, divination is the power to grasp and interpret the signs sent by Gods to human beings (De divinatione 2.130; Sextus Empiricus, Adversus mathematicos 9.132; Stobaeus, Ekologai 2.170). It has two parts, artifi­cial and natural. The former is so-called because the signs with which it is occupied require specialized expertise to interpret, while the natural division relies on things like inspired ut­terances and dreams which do not (though there are, unsurprisingly, complications having to do with the skilled interpretation that dreams and prophetic utterances do sometimes require). Though artificial divination is also concerned with the interpretation of portents, much the largest share of its attention is absorbed by signs discovered by long observation, whose ef­ficacy is explained along empirical lines and illustrated with examples drawn from medicine, viewed as an empirical art, and other arts viewed in the same way.

Nor do I ask why this tree alone should flower three times nor why it makes the time for ploughing fit with the sign of its flowering. I am content with this, that, even though I do not know why this happens, I do know what happens. So for every kind of divination I shall give the same answer as I did for the things I have cited. I see the efficacy of the scammony root for purging and birthwort for countering snake bites... and this is sufficient; I do not know why they work. In the same way I do not understand adequately the explanation for the signs of wind and rain.. I recognize, I know, and I vouch for the force and result of them (De divinatione 1.16; translation from Wardle 2006: 50).

Thus the Stoics came down squarely on the empirical side of a long-running debate about divination especially prominent in discussions of astrology. At issue was the question whether its efficacy is to be explained as the result of discovering the causal influences exerted on hu­man beings and their affairs by heavenly bodies or rather merely a matter of grasping empirical correlations the causes responsible for which remain hidden.^[11]

The fact that natural signs are the concern of artificial divination while natural divina­tion is occupied with what look rather like bearers of non-natural meaning is perhaps only a superficial paradox. Yet the distinctions with which we began are bound to take on a different look in the context of a view like the Stoics’, according to which the universe is governed down to the last detail by a providential deity whose benevolence extends to the provision of signs for us to read. The Stoics maintained that the world was so created at the beginning that certain signs run ahead of certain things (De divinatione 1.118, cf. 35). At the very least, the clean division between natural signs and bearers of natural meaning, which do not depend on intention for their significance, on the one hand, and given signs or bearers of non-natural meaning, on the other, which signify as a result of an intention to signify that must be grasped for this purpose to be effected, will not look quite the same.

One way to approach this point sets out from a familiar problem: How can experience of conjunctions among objects or events between which reason cannot discern any other relations furnish a ground or reason for inferring one from the other? One response, most famously as­sociated with David Hume, is to deny that it can and insist that the observation of conjunctions does not put us in possession grounds for inferences properly so called, but rather gives rise to customs or habits by which practice is governed in the absence of reason. It is noteworthy that there was a prominent strand of radical anti-rationalism among the medical Empiricists, some of whom insisted that they were not engaged in the business of reasoning at all, but were instead guided by dispositions, implanted by experience, to be reminded of one thing by the perception of another with which it had been conjoined in past observation. Others were willing to speak of reasoning, but insisted that the kind of reasoning that they employed was of an ordinary, everyday sort restricted to the phenomena, which they called epilogismos in order to distinguish it from reason of the objectionable rationalist kind, which they called analogismos.^{9 [12] As we have seen, however, conspicuous correlations among events between which reason can discern no connection were, according to the Stoics, deliberately contrived for the benefit of humankind by god.}

No doubt it is possible to be guided by these signs without being aware of or paying heed to the divine intention of which they are the expression. But one may also, and I take it the Stoic diviner will, go further and view divinatory signs as a system of divinely instituted signals, with the result that the faith he reposes in the signs that he studies will not be a mat­ter of either rationally groundless custom, on the one hand, or conviction grounded in purely empirical reasoning — supposing there is such a thing —, on the other, but more like the trust one places in the testimony of an unimpeachable authority. Long observation and experience will for him be a source of clues about what the gods mean to tell us, rather than being viewed simply as the source of grounds to be exploited in empirical reasoning or the causal basis for mental habits of association.

Or rather, they will be this in addition to being that. The Stoics were far from repudiating the idea of the empirical. We have seen Chrysippus appealing to it. It is plain that even in the art of divination as the Stoics conceived it there will be an empirical aspect or dimension to what is known in the sphere of artificial divination and an empirical level to the diviner’s understanding of it. This is implied by the comparison between divination and less exalted arts. The concern with divinely sent signs as such seems to be distinctive of the diviner’s art — witness the Stoic definition of divination — though it is an intriguing question whether the regularities on which empirical arts of a less elevated kind rely are also deliberately contrived by divine agency for the benefit of humankind. Certainly Stoic views about providence are not incompatible with the suggestion. Yet there are some differences. The more ordinary empirical arts, or arts with a substantial empirical component, are only at one remove from a grasp of the nature of the matters with which they deal and the causes at work in them, whereas such an understanding may be in principle impossible for human beings in the sphere of divina­tion. The divine intentions behind the regularities studied and exploited by, for example, the medical art are, one suspects, no business of the doctor as such. It is plausible to think that the perspective proper to medicine and other arts like it is a naturalistic one, even though to the Stoic way of thinking, this is a narrow or restricted way of viewing matters that can be subsumed in a broader perspective from which nature is seen as the expression of divine reason, indeed, in a sense, identical to it.

If this suggestion is on the right lines, the distinction between the natural and the non­natural does gain a purchase in Stoicism. Not only can there be analogues of indicative sig­nification, which do not raise the question that we have been considering — the conclusion of the sign-inference will be accepted on the strength of the rationally compelling grounds afforded by the sign, but the presumably much larger mass of signs grasped through long observation can be understood along purely empirical lines. What is more, they will be so un­derstood much of the time and by human beings reasoning in most capacities. What is striking and distinctive about the Stoics, however, is that one branch of divination as they conceive it is both an impeccably rigorous application of empirical method and a means of interpreting divinely given signals. Understood in one way and viewed from one perspective, the signs with which it is occupied are or are used as natural signs. Viewed in broader perspective, however, the empirically grounded sign-inferences that the diviner draws are not natural in a way that can be sharply contrasted with the non-natural. For they are not only the product of divine intentions, but of intentions whose divine author intends that they be recognized, at least by diviners, whose other tasks, it will be recalled, include interpreting other kinds of message from the gods, for example, portents.

7

Matters are otherwise when we turn to the Epicureans, whose views about the gods could hardly be more different from the Stoa’s. The gods of Epicurus, such as they are, did not cre­ate the world, exert no influence on it, and could not care less about human beings. Nothing in the world observed by human beings is the product of divine intention, and there is, as a result, a clean break between natural signs and the signs human beings create and give to one another, even if the Epicureans do not themselves speak of “signs” in this connection. The break stands out that much more clearly as, in the Epicurean view, the development of the latter depends on the prior existence of the former. Epicurus’ pioneering account of the origin of speech and language envisages a transition from an early phase in which human beings’ spontaneous vocal utterances serve as what we would call natural signs of their mental states and emotions, to later phases where the possibility of conveying information that is revealed in this way is deliberately exploited by human beings, who now fashion and use words in order to communicate their thoughts to each other (Letter to Herodotus 75-76; cf. Lucretius, De rerum natura 5.1056-90).^[13]

Our attempts to understand Epicurean views about sign inference have been greatly as­sisted by the survival, in the form of a papyrus buried at Herculaneum by the eruption of Mount Vesuvius in A.D. 79, of a work by the first-century B.C. poet and Epicurean philosopher Philodemus: On Signs and Sign-inferences (the De signis for short).^[14] Among the problems presented by what we find in it is one that has to do with the distinction between the empiri­cal and the rational, or rather its apparent absence. As we have already seen, the Epicurean position would seem at first to be a paradigmatic example of rationalist thought. According to empiricism, knowledge is confined to the phenomena, which are accessible to perception, and the patterns of conjunction and sequence that are observed to obtain among them and does not extend to so-called non-evident matters.

A very large part, perhaps the largest part, of Epicurus and his followers’ energies were occupied with natural philosophy. Their motives were idiosyncratic to be sure, namely, by offering a purely naturalistic account of nature and natural phenomena to remove divine agency from the picture and so free human beings from superstition, which was in their — the Epicureans’ — view the principal obstacle to happiness. To this end, Epicurus elaborated an atomic theory of matter and offered explanations for natural phenomena, paying special attention to heavenly phenomena.

To show how we could in fact know the contents of his theory, he also developed an epistemology. This theory seems to fit very comfortably in Sextus’ epistemological frame­work. Direct observation of the phenomena secures ground-level truths, which in turn serve as points of departure for sign-inferences and demonstrations by means of which truths about the non-evident realm are won, whether about atoms, rendered inaccessible to perception by their smallness or heavenly bodies, put beyond the reach of observation by their distance from us (Epicurus, Letter to Herodotus 38, 39; Letter to Pythocles 87, 97, 104; Diogenes Laertius 10.32). It looks very much as if the Epicureans are to be classified as rationalists who sub­scribed to a theory of indicative signs, as Sextus conceived it, even if they did not describe themselves in this way or use the term “indicative sign” itself (and those who did held a view in some ways different from what Sextus leads us to expect).

To judge by Philodemus’ testimony and hints from other Epicurean works, however, this expectation was not fulfilled. We search in vain for the contrast that defined the controversy between rationalism and empiricism. The position that we find instead appears to occupy a no-man’s land that should not exist according to the framework of assumptions in terms of which rationalists and empiricists defined their opposition to each other. The medical Empiricists define experience as knowledge of what has been observed to occur in the same way many times. That a ring around the moon precedes rain or that venesection is followed by the remission of fever become part of experience by being observed repeatedly. No amount of observation, however, can make these anything other than empirical generalizations by grasping which we know that without being any closer to understanding the underlying causes and natures because of which things are as they are observed to be and in terms of which a genuine explanation of why they are would have to be formulated. One important consequence is that the so-called transition to the similar whereby we take things similar to those of which we have had experience to be similar to them cannot be a source of new knowledge by itself, but only a source of hypotheses which must be confirmed by observation before they become known by becoming part of experience.^[15]

According to the Epicurean views preserved by Philodemus, sign-inferences, whether about humdrum matters like smoke and fire or the fundamental truths of physics, are all grounded in what looks very much like the repeated observation of the same thing that is the Empiricists’ point of departure. Indeed, the Epicureans sometimes speak, as the Empiricists did, of experience and history. Yet somehow the result of such observation is that it becomes inconceivable that things could be other than they have been seen to be. And the scope of the inferences that we are entitled to draw on the basis of observation is not confined to items of precisely the same type as those that have been observed. Not only may we infer that all hu­man beings are mortal wherever they may be from the fact that those we have observed are, but our knowledge of atoms and the void is based on inferences from the observed behavior of medium-sized bodies in our vicinity. What is more, the knowledge we gain in this way far from being restricted to facts that — empirical truths as we have been calling them — em­braces necessary truths about the ultimate causes of things in terms of which everything else is to be explained and understood.

That this runs counter not only to our expectations but to those of the Epicureans’ philo­sophical contemporaries is plain from the form and content of the De signis itself. The work takes the form of series of objections to Epicurean views with replies by Epicurean authorities. The opponents are not specified by name. They are usually thought to be Stoics, though it has been plausibly suggested that they were Academic skeptics. Be that as it may, they appear to have been moved by concerns of just the kind that we would expect, as we can see from the questions with which they challenge the Epicureans. “Why should the fact that all the human beings whom we have observed are mortal exclude the possibility that human beings whom we have not observed might be immortal?” “Why should the fact that bodies of observable size move only through surroundings relatively empty by comparison with them entitle us to infer that atoms move through absolutely empty space, that is, a void?” And “If the observed behavior of visible bodies is the basis of inferences to conclusions about the atoms, should we not infer that the so-called atoms are in fact breakable like all bodies in our experience without exception?”

The Epicureans had much to say in their own defense as the De signis makes clear. One way of describing their position would be to say that it defies or overcomes the limitations on experience as they are understood in the debate between rationalism and empiricism in both its ancient and modern versions. This way of putting things is, however, misleading if it sug­gest that the Epicureans made larger claims for what went under the name of “experience.” So far as one can tell, they understood terms like “experience” and “observation” as others did. Rather, they seem to have supposed that observation furnished the basis for a grasp of the phenomena that was, if you will, more than empirical because it amounted to a limited grasp of the natures and causes at work in what was observed, which in turn furnished the basis for inferences to conclusions about the unobserved and the unobservable. A part in their account was played by epilogismos, which, however, differs in ways that are hard to get a fix on from what went under that head among the medical Empiricists.^[16] The account as a whole presents many difficulties, and not only because of the poor state of the mainly papyrlogical evidence on which we are obliged to rely.

JAMES ALLEN

Grappling with those difficulties is a task for another day, however. The object of this essay is not to get to the bottom of these problems, but to draw attention ancient Greek philo­sophical views about signs that do not fit easily with our assumptions, even though those assumptions belong to a framework that we have largely inherited from the Greeks. The existence of such views does not show that the framework is anything other than sturdy and useful in the extreme, but rather that it was not obvious or inescapable.

BIBLIOGRAPHY

Adamson, P.

2008 “Plotinus on Astrology.” Oxford Studies in Ancient Philosophy 35: 265-91.

Allen, James

2001 Inference from Signs: Ancient Debates about the Nature of Evidence. Oxford: Oxford

University Press.

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