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Umberto Eco’s Encyclopedia vs. Porphyry’s Tree

  • Andrei Cornea

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  • Andrei Cornea
    Department of European Cultural Studies
    University of Bucharest

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Ever since Hegel taught us that “the historical succession of philosophical systems is the same as the succession of the conceptual determinations of the Idea in their logical derivation”,[1] the borderline between philosophy and the history of philosophy has become increasingly blurred. This may not be bad in itself ; yet, for all its possible merits, the overlapping of philosophy and its historical interpretation poses a risk ; indeed, today it is difficult to know what legitimate task the interpreter or the historian of a philosopher of the past still has : should he confine himself just to explaining an earlier text according to its allegedly original meaning (provided one is able to discover it), or should he try merely to read the arduous dilemmas of his own age in a text of another age ?[2] In other words, are there any limits to interpreting someone else’s system of thought ? Should we avoid at any cost dislodging this system from its original life-setting, imposing our own ideas on it, and counting it among the supporters of our own obsessions ? Or, rather, should we only avoid abuses, but accept a “reasonable” modernization, enabling a vivid “dialogue” with thinkers since long passed away ? But who exactly knows what “reasonable” and “abuse” mean in this context ?

Since I do not think we have a rule to guide us on this matter, I suspect that all we can do is resort to casuistry : it is only individual cases that may enlighten us to a small extent with respect to what an abusive, context-free interpretation, or, conversely, a legitimate one may represent. Therefore, in what follows, I shall try to discuss two closely related texts written by a famous philosopher of our times. I shall ask myself whether or not this author tried to abusively annex a certain tradition of thought to his own philosophy, and whether or not he transgressed the “reasonable” limits of historically interpreting some philosophers of the past. The present text is not a critique of this great author for the sake of mere critique, but just a very limited attempt to more clearly see into the fruitful, but tense relationship between philosophers and their interpreters.


The author I will refer to is Umberto Eco, and his two closely related texts are a) Chapter 2, called “Dictionary vs. Encyclopedia” (DvE) from his book Semiotics and the Philosophy of Language[3] ; b) an essay called “Anti-Porphyry” (AP) published in a collective volume.[4] AP is considerably shorter, while its stand appears to be more radical. There are a few other interesting differences between DvE and AP on which I shall elaborate further on.[5]

In both texts Eco sharply distinguishes between two species of thought which he calls “dictionary-like semantics” and, respectively, “encyclopedia-like semantics”. In AP Eco assimilates the former kind to “strong thought”, i.e. to essentialism or realism, especially because it can satisfy the following major requirement : “Il mondo-modello, le cui strutture il linguaggio rispecchia, deve presentare omologie con il mondo naturale della nostra esperienza, almeno sotto qualque aspetto”.[6]

In AP, Eco also associates the latter way of thinking with “il pensiero debole” (the “weak thought” proposed by Gianni Vattimo) and, in DvE, with a few other anti-essentialist projects, which generally deny the existence of a knowable and objective reality “out there” and hold that any “reality” is context-dependent. Eco sees strong thought being traditionally epitomized by the model of the “Porphyrian tree”, while an appropriate contemporary model of weak thought is the “labyrinth”, particularly in the form of the rhizome, as earlier proposed by G. Deleuze and F. Guattari.[7] Eco contends that “Porphyry is still alive in many semantic theories” of today, which unfortunately makes them suffer from what he calls “a theoretical cramp”.[8] On the other hand, Eco thinks he can discover at least two reputed forefathers of weak thought or rhizome-like way of thinking : Thomas Aquinas and d’Alembert, in his Discours préliminaire to the French Encyclopédie. Our focus will be exclusively on the way in which Eco discusses the alleged “forefathers” of weak thought.

So, in his usually brilliant, paradoxical, and erudite manner, Eco tries to prove two main points : a) “the untenability of that model for definition, structured by genera, species and differentiae, known as the Porphyrian tree”,[9] because allegedly it has been logically subverted from within by weak thought since long ; b) the postmodern weak thought Eco wholeheartedly advocates was not only anticipated by some important thinkers of the past, such as Aquinas and d’Alembert, but also legitimized somehow by them ; therefore, it has not only logic, but also history on its side.

I believe that neither point was properly proven. In my opinion, in order to make his thesis sound plausible, Eco not only overstretched to the limit the meaning of some texts he chose in order to serve his argument, but — and this is extremely disturbing — he particularly “expurgated” almost completely d’Alembert’s Discours of an important topic which, had it been present, could have weakened his hypothesis. By this device Eco apparently succeeded in turning upside down the meaning of the word “encyclopedia”, such as it was understood by the French encyclopedists and, paradoxically, in getting the term stuck to something I see very much as opposed to it in spirit — il pensiero debole, epistemological relativism, or the rhizome of postmodern anti-essentialism. Essentially, I suspect that the alleged affinities between Aquinas, d’Alembert and Umberto Eco’s encyclopedia-like semantics, or weak thought, or rhizome remain very questionable.


As I have mentioned above, U. Eco’s model for what he calls strongthought or dictionary-like thought is the famous “Porphyrian tree” — actually the medieval iconic representation of the content of a passage from Porphyry’s Isagoge, a school commentary on Aristotle’s Categories. Boethius translated into Latin this short didactic treatise which turned out to be extremely influential on medieval thought by unleashing what later was called “the quarrel of universals”.[10] Let me quote this relevant passage from Isagoge : “Substantia est quidem ipsa genus, sub hac autem est corpus, sub corpore vero animatum corpus, sub quo animal, sub animale vero rationale animal, sub quo homo, sub homine vero Socrates et Plato et qui sunt particulares homines”.[11]

After having accurately described how, according to Porphyry, species are embedded in genera, and how differentiae work in order to divide upper genera into lower genera and so on, up until the last species, which are indivisible into other species and under which there are but individuals, Eco tries to argue for the logical untenability of the tree, as a method of representing the structure of knowledge. He claims that : “[…] il crampo logico che affetta ogni dizionario teorico si manifesta all’origine stessa del problema e cioè nella teoria della definizione formita […] nella Isagoge di Porfirio il Fenicio”.[12]

He finds at least two major inconsistencies with this theory, which, allegedly, subvert the Porphyrian tree from within and from its very outset :

a) a given hierarchy between certain genera and species seems to be arbitrary rather than necessary : for instance, at a certain point, Porphyry divides the upper genus animal by means of the differentiae rational/irrational.[13] Then he divides again the lower genus rational-animal by means of the differentiae mortal/immortal and, eventually, he obtains two species : man, who is a mortal rational-animal, and god, who is an immortal rational-animal. (Rational-animal is the lower genus shared by both men and gods, who differ by species.) Now, if we want to tell the difference between, say, man and horse (a mortal irrational-animal), we have to start once again from the common upper genus animal, once more we must divide it by means of the differentiae rational/irrational, and then divide the other lower genus irrational-animal by means of the differentiae mortal/immortal. As a result, man and horse turn out to belong to different lower genera and not just to different species, and so their differentia turns out to be a generic one, larger than the specific one. But — Eco says — nothing prevents us from inverting the above-mentioned order of division. And indeed, Porphyry offers a different division, as well.[14] Eco also quotes Abélard who in his Editio super Porphyrium accepted that upper genera may be divided into subordinate genera in different ways and, therefore, differently conceived of.[15]

In fact, one could logically define man indifferently either as a mortal rational-animal, or as a rational mortal-animal, where rational-animal and mortal-animal could both be genera proxima alternatively predicated of the same species : man. Yet, these genera were differently built by alternative and equally possible divisions of the upper genus animal. But if we adopted the latter division, man and horse would belong to the same subordinate genus and would differ only in species, while man and god would differ in genus. Consequently, Eco suggests, the construction of the tree becomes relative to one’s own particular perspective, as the tree “can be freely reorganized according to alternative hierarchies”.[16] Which is paramount to saying that essentialism dissolves itself into relativism, because of its internal logical inconsistencies !

b) Eco notices that, by adding differentia after differentia to the supreme genus (of this category), substantia — such as corporeal,animate,sensitive,rational,mortal —, genera and species actually become just “clusters of differentiae”.[17] Now, differentiae are qualities, not substances and, therefore, the Aristotelian, basic distinction between substance and the rest of categories evaporates and is in fact reduced to a “verbal ghost” : “Si potrebbe […] dire que la sostanza altro non è que la matrice vuota di un giocco di differenze. Generi e specie sono fantasmi verbali que coprono la vera natura dell’albero et dell’universo que esso rappresenta, ununiversodipuredifferenze”.[18]

Further, Porphyry’s differentiae are basically twofold : specific differentiae (differentia specifica, diaphora eidopoios) and accidental differentiae, which are very often assimilated to accidents ; accidents (accidentia, ta symbebekota) are themselves twofold : intrinsic (kath’hauto) and extrinsic or separable accidents (separabilia, chorista). The specific differentia belongs to the definition or the notion (logos) of a substance by joining genus proximum (e.g. : man is a mortal rational-animal). Intrinsic accidents are differentiae that are always and necessarily predicated of the subject, although they do not belong to the notion, such as the equality of the angles of a triangle with two right angles, which is not part of the notion of triangle.[19] On the contrary, separable or extrinsic accidents are unnecessary accidents, which may occur by chance, such as a certain size or shape of a certain triangle.

What Eco wants to prove is that not only there is no relevant distinction between essential and accidental differentiae, and also between intrinsic and extrinsic accidents, but that even some ancient philosophers, like Aquinas and perhaps Aristotle, were aware of this situation. Eco writes : “According to Aristotle their number (of the differentiae) cannot be known a priori (Metaphysics, VIII, 2, 1042b-1043a). It is true that he says this of non-essential differentiae, but who really knows which differentiae are strictly essential or specific ?”[20]

Actually Aristotle says nothing of the kind. He only gives a lot of examples of the diversity of specific (not accidental) differentiae of various sensorial things. Yet he assigns each class a single specific differentia and not an indefinite number, as Eco suggests. For instance, “the threshold is a piece of wood placed in a determined way”, “ice is solidified or condensed water in this determined way”, etc. What we cannot know a priori is the total number of classes or substances, not the number of specific differentiae assigned to each class — which number is but one. So, I do not understand how substances can turn out to be just “clusters of differentiae” !

But the obvious implication of Eco’s rhetorical question is that already for Aristotle there could be no clear-cut distinction between specific and accidental differentiae and that, practically, all differentiae have a tendency to develop into non-essential, extrinsic and even arbitrary accidents.[21] This makes strong thought be intrinsically inconsistent, since it gets subverted from within by an all-pervading weak thought.

Eco goes further and tries to convince the reader that this relativist conclusion was already shared by Thomas Aquinas. He quotes the following passage from De Ente et Essentia, 6 : “In rebus sensibilibus etiam ipsae differentiae essentiales nobis ignotae sunt : unde significantur per differentiae accidentales quae ex essentialibus oriuntur, sicut causa significatur per suum effectum, sicut bipes ponitur differentia hominis”.[22]

Eco comments : “[…] essential differentiae cannot be known directly by us ; we know (we infer !) them by semiotic means, through the effects (accidents) they produce, and these accidents are the sign of their unknowable cause”.[23]

And also : “[…] quelle que conosciamo come differenze specifiche non sono le differenze essenziali stesse, ma ne sono per così dire dei segni […] ; sono manifestazioni superficiali dell’essere di qualcosa d’altro, per noi incognoscibile”.[24]

As we can see, Eco imperceptibly slips from “essential differentiae not known directly by us” to “their unknowable cause”, and from “what we know as specific differentiae are not essential differentiae themselves” to “superficial manifestations of the being of something else which is unknowable to us”. In Eco’s terms, Aquinas’s analysis of scientific knowledge surprisingly becomes a statement of agnosticism. So, Eco concludes the analysis of Aquinas’s texts quite explosively :

Thus ‘rational’ is an accident (sc. of man) and so are all the differentiae in which the traditional Porphyrian tree dissolves itself. The tree of genera and species, the tree of substances, blows up in a dust of differentiae, in a turmoil of infinite accidents, in a non-hierarchical network of qualia. The dictionary is dissolved into a potentially unordered and unrestricted galaxy of pieces of world knowledge. The dictionary thus becomes an encyclopedia, because it was in fact a disguised encyclopedia.[25]

And what is this “encyclopedia” like, after the discovery of its presence in the shadow of the tree ? It is purely relativistic and parochial : it is just local knowledge that “cannot be recognized and organized as a global system ; it provides only ‘local’ and transitory systems of knowledge which can be contradicted by alternative and equally ‘local’ cultural organizations ; every attempt to recognize these local organizations as unique and ‘global’ — ignoring their partiality — produces an ideological bias”.[26]

The subversion from within of strong thought seems to have won the day.


a) I think Eco shows a tendency to jump to conclusions that no relevant texts support. So is the above-mentioned one : “thus ‘rational’ is an accident and so are all the differentiae […]”. The reader may be under the impression that Thomas Aquinas endorsed this conclusion, or at least was inclined to do it, but in fact it is just Eco who tries to wrongly annex Aquinas to his own anti-essentialist belief. Actually Aquinas states quite plainly that essential differentiae, on the one hand, and accidental, either intrinsic or extrinsic differentiae, on the other, must be thoroughly distinguished : “[…] homini, in eo quod est homo, convenit rationale et animal, et alia quae in ea definitione cadunt ; album vero vel nigrum vel quodcunque huiusmodi, quod non est de ratione humanitatis, non convenit homini in eo quod est homo”.[27]

Therefore, according to Aquinas, “rational” is an essential differentia of man and not an accident, because it belongs to the definition or substance of man as man, while “black” or “white” are just extrinsic accidents, since they are not included into man’s rationality, nor are they inseparable from man’s being. This is why they do not fit (non convenit) man as man. So, not all differentiae are alike !

Moreover, not all accidental differentiae are alike, either : what Aquinas really said in the passage quoted above by Eco from De Ente et Essentia is that “in rebus sensibilibus” we cannot know directly the essences themselves ; yet, we can know them from their necessary effects which are intrinsic accidents of those respective things. Here “differentiae accidentales” has the meaning of intrinsic accidents, not of extrinsic or separable accidents, as Eco seems to have construed it. Therefore, the link between essence and intrinsic accident (or between cause and its necessary effect) is underscored by Aquinas, not dissolved, and it is necessary, not fortuitous. We can deduce from — say — the fact that man can laugh that he is a rational animal, because laughing is a necessary effect (intrinsic accident or an accidental, intrinsic differentia)[28] of the rational essence of man (unlike his skin color, which is an extrinsic accident), and so we get an indirect, yet precious and real knowledge of the essence of man. Therefore, necessary effects are not “superficial manifestations”, nor are so the causes or essences of sensible things ultimately “unknowable to us”. They are knowable, though indirectly, by means of reasoning and science. Unlike them, it is the essences of separate beings, the existence of which we can still infer, that are unknowable to us during this lifetime.[29]

Generally, if there were no accepted distinction between essential and accidental differentiae on the one hand, and between intrinsic and extrinsic accidents on the other, all our knowledge would be just an exercise of conjecturing. And without the belief that intrinsic accidents (effects) can necessarily lead even to their essential, supreme causes, Aquinas would have never tried to prove God’s necessary existence :

Respondeo dicendum quod duplex est demonstratio. Una quae est per causam, et dicitur propter quid : et haec est per priora simpliciter. Alia est per effectum, et dicitur demonstratio quia : et haec est per ea quae sunt priora quoad nos : cum enim effectus aliquis nobis est manifestior quam sua causa, per effectum procedimus ad cognitionem causae. […] Unde Deum esse, secundum quod non est per se notum quoad nos, demonstrabile est per effectus nobis notos.[30]

Eco also refers to a passage he regards as crucial, taken from Summa contra Gentiles,[31] suggesting that Aquinas thought man cannot know what he is (quid est), but only that he is so (quod est). Eco’s conclusion is that to Aquinas essences even of res sensibiles remain forever unknown, and consequently we should perhaps ignore them altogether as irrelevant.[32] But if we attentively read the whole passage (and not just part of it, like Eco), we get a different understanding of it : Aquinas actually argues that the soul (and not man as such, whose supreme knowing power is the intellect) cannot know about herself by herself (de seipsa per seipsam) what she is (i.e. her essence) ; she can only know by her own means that she exists (quod est). So, most people err with respect to the essence of the soul. However — Aquinas says —, we possess the theoretical sciences (scientiae speculativae) which allow us to know what the soul really is (her essence, quod quid est) by means of theoretical thinking, which deduces causes from their necessary effects, as he clearly states at the end of this chapter[33] : “Sicut de anima scimus quia est per seipsam, inquantum eius actus percipimus[34] ; quid autem sit, inquirimus ex actibus et obiectis per principia scientiarum speculativarum : ita etiam de his quae sunt in anima nostra, scilicet potentiis et habitibus, scimus quidem quia sunt, inquantum actus percipimus ; quid vero sint, ex ipsorum actuum qualitate invenimus.”[35]

So, if essences were manifest, science would be useless. But if no essences at all could be inferred from their intrinsic accidents (necessary effects), and these could not be distinguished from the extrinsic ones (arbitrary accidents), science would be impossible. So again, contrary to what Eco wants us to believe, Aquinas thinks causes and essences of sensorial things are ultimately knowable to us by means of the theoretical sciences (scientiae speculativae). Therefore it is preposterous to attribute Thomas Aquinas a relativist creed — well-suited, say, to Richard Rorty.[36]

Of course, Eco is free to believe whatever he likes regarding essences, differentiae and accidents, and he is entitled to criticize the essentialist conception of Aristotle, Porphyry or Aquinas. What he is less entitled to, in my opinion, is to annex these writers of the past to his own anti-essentialist conception by means of what I would call a distortion of their thought.

b) In AP, U. Eco says that Aquinas “understood that differentiae are accidents”,[37] but could not afford to draw all the consequences from this conclusion, because — Eco said — politically and psychologically, Thomas was more or less consciously still bound to a worldview according to which “the tree imitates the structure of reality” (l’albero mimi la struttura di reale). Here we encounter perhaps Eco’s main misinterpretation concerning these old texts. So, let us remember what the major prerequisite that Eco himself had assigned to strong thought was, as epitomized by the Porphyrian tree : “Il mondo-modello, le cui strutture il linguaggio rispecchia, deve presentare omologie con il mondo naturale della nostra esperienza, almeno sotto qualque aspetto.”

The above means that for strong thought (or what he calls “dictionary-like semantics”), logic cannot be separated from ontology and metaphysics as a matter of principle, if not in every detail, because together they make up an organic whole.[38] The link between logic and ontology is a metaphysical theory of truth as homology or correspondence between the exterior world and the logos.[39] Unfortunately Eco forgets this characteristic which he himself had quite correctly ascribed to strong thought previously, for he sets out to discuss the Porphyrian tree as a mere logical device, detached from its ontological and metaphysical counterparts : “We can disregard the metaphysics underlying the Porphyrian tree, since we are interested in the fact that this tree, independent of its alleged metaphysical grounds and conceived as a representation of mere logical relationships, has influenced all subsequent discussions on the method of definition.”[40]

Yet, this purely logical approach is exactly what we should not accept, if we treated the Porphyrian tree as a model ofstrong thought ! Indeed, what Eco does is to subvert strong thought himself, precisely because he seeks to reduce it to mere logic, while pretending on the other hand that strong thought (or dictionary-like thought) is self-subverting and logically untenable ! Of course, a Porphyrian, Aristotelian, Platonic or any other version of strong thought can be criticized, contested or done away with at any time. But to criticize this worldview as a whole, as a common foundation of both metaphysics and logic — which is perfectly legitimate — is one thing, and another, a very different one indeed, is to halve it first and then point at the alleged self-inconsistency of either of the extant halves.

Of course, Eco is right in saying that, from a strictly logical point of view, man’s genus proximum can be either rational-animal or mortal-animal, as his differentia can be either mortal or rational, depending on how one divides the upper genus animal. But this alternative logical approach can only have a didactic significance for a Neo-Platonist, as Porphyry plainly stated at the beginning of Isagoge.[41] He may have also suggested the same strictly logical perspective, appropriate just to school exercises, when he said that, on the one hand, man and horse do not differ by genus, as being both mortal, and, on the other, that man and god do not differ by genus, either, as being both rational.[42] But neither Porphyry, nor Plotinus, nor Plato, nor Aristotle, nor any other philosopher, maybe until Hume or Kant, could have imagined logic being ultimately cut off from metaphysics and ontology.[43]

In fact, man’s natural genus proximum had to be rational-animal rather than mortal-animal, because man was thought to be closer to gods than to beasts. (If man’s genus proximum is rational-animal, men and gods will form a unity by their genus proximum — rational-animal —, while men and beasts will form a unity only by their upper genus : animal.) Why so ? Because man, owing to his intellect, which enables him to transgress somehow his mortality, was supposed to have a share in the divine, as Aristotle had made clear centuries before Porphyry : “But we must not follow those who advise us, being men, to think of human things, and, being mortal, of mortal things, but must, so far as we can, make ourselves immortal, and strain every nerve to live in accordance with the best thing in us (reason) ; for even if it be small in bulk, much more does it in power and worth surpass everything.”[44]

As with respect to the relationship between gods, men and beasts, he adds : “[…] the other animals have no share in happiness, being completely deprived of such activity. For while the whole life of the gods is blessed, and that of men too in so far as some likeness of such activity belongs to them, none of the other animals is happy, since they in no way share in contemplation”.[45]

Therefore, I think one can hardly doubt that man’s natural differentiae in the Porphyrian tree had to be arranged ultimately according to this order, animal, rational, mortal (an order usually followed by Porphyry, Boethius, Abélard, Thomas, etc., in most of their examples) rather than to any other one, no matter how logically accurate in itself.[46] The rationale for the above-mentioned arrangement was that it was thought to fit a metaphysical, generally-shared idea of man — his closer kinship with gods, rather than with beasts.[47] Therefore, we cannot accept Eco’s formula that the ancient or medieval strong thought may have conceived the tree as being “a context-sensitive structure”,[48] unless we want to modernize and dislodge this thought from the outset.

Naturally, while committed to some didactic, limited purposes, a writer like Porphyry or Boethius could postpone explaining why a certain upper genus, like animal, was preferably divided in a certain way ; they could even admit another division for the sake of demonstration. But as a matter of principle, apart from the sophists and the skeptics, no ancient or medieval philosopher could have ever agreed with Eco that the tree of nature and knowledge “can be freely reorganized according to alternative hierarchies”.[49] Unlike many modern and postmodern thinkers, all those philosophers clung to a worldview where logic, ontology and metaphysics were ultimately inseparable. This is exactly what strong thought is all about. Is it, then, self-subverting, as Eco claims ? In fact, one is allowed to argue either for, or against its alleged inconsistency, if only one takes strong thought seriously, i.e. as a whole — which is exactly what Eco failed to do.


Still, Aquinas allegedly was only a “remote relative” of Eco’s encyclopedia-like thought ; remember that, according to Eco, though perceiving its internal inconsistencies, Doctor Angelicus would not give up “the tree”, because of some “political and psychological” resistances. On the contrary, Eco holds that, with d’Alembert’s Discours préliminaire, weak thought, modelled on what he calls the labyrinth of the 3rd type and epitomized by the rhizome, was already ripe : “Il labirinto di terzo tipo […] è il modello que è stato scelto da un pensiero debole per eccellenza, quello degli enciclopedisti del xviii secolo, un pensiero della ragionevolezza illuministica, non della razionalità trionfante.”[50]

In DvE he seems to be a little more cautious : the Encyclopédie and the Enlightenment are said to be only “a midway solution between the tree and the rhizome” ; still, they “made in fact the rhizome thinkable”.[51]

In my opinion, however, U. Eco approaches d’Alembert in the same “post-modernizing” way he approached Porphyry or Aquinas : he first cripples and halves the system of strong thought he is dealing with ; then he declares what remained of it to be deeply permeated by weak thought, or even to be weak thought “par excellence” : “The project of the encyclopedia competence is governed by an underlying metaphysics or by a metaphor (or an allegory) : the idea of labyrinth. The utopia of a Porphyrian tree represented the most influential attempt to reduce the labyrinth to a bidimensional tree. But the tree again generated the labyrinth.”[52]

Now, let us first examine what Eco understands by labyrinth and/or rhizome. Actually, according to him, there are no less than three types of labyrinths :

The first type is the least important one. It is a skein which, if unwound, becomes a continuous line. It is more elementary than the Porphyrian tree and has nothing to do with an encyclopedia.

The second type of labyrinth is called by Eco a maze. Historically, he discovers its iconic presence in the so-called Irrweg of mannerism. Interestingly enough — Eco says — this kind of labyrinth is, in fact, a disguised tree, for if one unwinds a maze, one gets a Porphyrian tree. Its main characteristic is, therefore, the fact that there are privileged choices between the different paths one can take : a few are dead ends, which obliges one to turn backwards, while some others lead one to new paths and ultimately to the way-out. So, “in a maze one can make mistakes.”[53] By and large, the maze is still representative of strong thought, though in a disguised manner. This is a very important conclusion, as we shall see further.

The “plain” labyrinth and the only genuine model of weak thought or of Encyclopedia-like semantics, according to Eco, is what he calls the “labyrinth of the third type”. It is a net and it can also be called a meander or a rhizome. “One cannot unwind it.” In a net “every point can be connected with every other point”. Therefore, one cannot make mistakes here : every path is as apt as any other to lead to any other point. Moreover, the non-contradiction principle does not apply to a net or a rhizome : “[…] it is true at the same time both that if p, then q, and that if p, then non-q.” “The rhizome justifies and encourages contradiction.”[54] Another important characteristic of the rhizome is its anti-genealogical and anti-hierarchical structure, precisely because the net is not a tree, nor can it be determined to become one, as it was possible with the labyrinth of the 2nd type. Generally, the labyrinth of the 3rd type has no privileged parts, and of course, no center. Moreover, unlike the labyrinth of the 2nd type, the labyrinth of the 3rd type has no outside, either : that is, one cannot get a global view of it ; one can only describe it “as a potential sum of local descriptions”.[55]

Now, how can a labyrinth of the third type show a “ragionevolezza illuministica” rather than epitomize the Feyerabendian “anything goes” remains a riddle to me. But let us examine what “labyrinth” meant to d’Alembert.

Eco quotes a long passage from d’Alembert’s Discours, where the French encyclopedist, while discussing the organization of knowledge, speaks both of the labyrinth and of the tree. Eco claims that “he (d’Alembert) puts it into question (the tree), speaking instead of a world map and a labyrinth”.[56]

In fact, d’Alembert, after having offered a sensualist and genetic theory of the progress of knowledge, and admitted that the “encyclopedic order of knowledge” is different from the “historical order” of the same, according to which sciences and arts were actually found, builds his own Porphyrian tree of universal knowledge. Then, he discusses it at length and appends the pictorial representation of the tree to the text.

Yet, faithful to his idea that weak thought subverts and transforms strong thought from within, Eco tries to show : a) that the labyrinth whereof d’Alembert speaks is a labyrinth of the third type, i.e. a rhizome, irreducible to a tree ; b) that what remains of the tree in the Discours can easily be almost disposed of. But before turning our attention to these points, let us quote d’Alembert’s relevant passage :

Le système général des sciences et des arts est une espèce de labyrinthe, de chemin tortueux où l’esprit s’engage sans trop connaître la route qu’il doit tenir. Pressé par ses besoins, par ceux du corps auquel il est uni, il étudie d’abord les premiers objets qui se présentent à lui ; pénètre le plus avant qu’il peut dans la connaissance de ces objets, rencontre bientôt des difficultés qui l’arrêtent, et, soit par l’espérance ou même par le désespoir de les vaincre, se jette dans une nouvelle route ; revient ensuite sur ses pas, franchit quelquefois les premières barrières pour en rencontrer de nouvelles, et, passant d’un objet à un autre, fait sur chacun de ces objets, à différents intervalles et comme par secousses, une suite d’opérations dont la discontinuité est un effet nécessaire de la génération même de ses idées. Mais ce désordre, tout philosophique qu’il est de la part de l’esprit, défigurerait, ou plutôt anéantirait entièrement un arbre encyclopédique dans lequel on voudrait le représenter […].

Il n’en est pas de même de l’ordre encyclopédique de nos connaissances. Ce dernier consiste à les rassembler dans le plus petit espace possible, et à placer, pour ainsi dire, le philosophe au-dessus de ce vaste labyrinthe dans un point de vue fort élevé d’où il puisse apercevoir à la fois les sciences et les arts principaux ; voir d’un coup d’oeil les objets de ses spéculations et les opérations qu’il peut faire sur ces objets ; distinguer les branches générales des connaissances humaines, les points qui les séparent ou qui les unissent, et entrevoir même quelquefois les routes secrètes qui les rapprochent. C’est une espèce de mappemonde qui doit montrer les principaux pays, leur position et leur dépendance mutuelle, le chemin en ligne droite qu’il y a de l’un à l’autre, chemin souvent coupé par mille obstacles, qui ne peuvent être connus sur chaque pays que des habitants ou des voyageurs, et qui ne sauraient être montrés que dans des cartes particulières fort détaillées. Ces cartes particulières seront les différents articles de l’Encyclopédie, et l’arbre ou système figuré en sera la mappemonde.[57]

We must notice that the labyrinth concerns only the genealogical or historical order of our knowledge and not what d’Alembert calls the “encyclopedic order”. One cannot provide a simple and clear arrangement of the former, but we can and must do it with respect to the latter. Nonetheless, these two orders are compatible and complementary. This property will enable the philosopher to show how sciences, arts, etc. essentially relate to one another ; he will be using the tree that allows us to embrace the whole knowledge “with a single glance”. Thus, “encyclopedic” means essential, synchronic, global to d’Alembert, that which is exactly what it does not mean to Eco. In Aristotle’s terms, Eco’s and d’Alembert’s “encyclopedias” are simply homonymous words !

It is urgent to ask ourselves which type of labyrinth d’Alembert had in mind. Eco tacitly assumes that d’Alembert’s is a labyrinth of the 3rd type, i.e. a net or a rhizome. But, as the Italian philosopher had said before, in such a labyrinth “every point can and must be connected with every other point”, which means that dead ends and mistakes are impossible. Yet, d’Alembert speaks of “a tortuous road”, rife with dead ends, where one moves by a trial-and-error process : the spirit advances, then runs into difficulties, it has to recoil and to take another path. Sometimes, the traveler succeeds in overcoming some barriers and moves further, only to find new obstacles in his way. So, there are right and wrong paths within his labyrinth and a certain hierarchy between them is possible, unlike what one finds within Eco’s net, where “anything goes”. How, then, could d’Alembert’s labyrinth be illustrative of the net ? How could someone either find new barriers, or get through, or get lost, or confused, or be successful, while he is running in the net ?

Besides, as we know, Eco’s labyrinth of the 3rd type rejects the non-contradiction principle, which is not at all the case with d’Alembert’s labyrinth. Indeed : here the opposite ways have to be meaningfully distinct, in order to make the choice between them significant. For otherwise, all movement would be meaningless. In the net, choices were hardly significant : since a may entail both b and non-b, whichever way one takes from a, the result is equally right. How could d’Alembert have imagined science advancing at random ? On the other hand, d’Alembert’s labyrinth is built by genealogical succession, while Eco’s labyrinth of the 3rd type was declared anti-genealogical. Further, if there is no ultimate way out of d’Alembert’s labyrinth (because knowledge is infinite), there is in it, however, a general direction that the human spirit follows : the advance of science, no matter how irregular, is nonetheless continuous over long periods of time — his labyrinth is decisively oriented towards progress. How else could have imagined things this typical representative of Enlightenment ?

Of course, d’Alembert’s labyrinth can be described as a diachronic succession of “local maps”, as he explains, which are the articles of the Dictionary. Yet, an overall view of them remains possible and necessary. And precisely to provide us with it will be the job of the “philosopher”, placed “above” and embracing the whole labyrinth “with a single glance”, as “a world map”. How, then, could this single glance catch a view of a rhizome — a structure that, as a matter of principle, cannot be described globally ?

Briefly, the labyrinth which d’Alembert depicts in his Discours strongly resembles Eco’s labyrinth of the 2nd type — the maze, or the Irrweg rather than the labyrinth of the 3rd type the rhizome or the net. This is a very important conclusion, because we remember that “if one unwinds a maze or a labyrinth of the 2nd type, one gets a particular kind of tree in which certain choices are privileged with respect to others”. And reciprocally : “A Porphyrian tree can become a maze of this type.” So, eventually d’Alembert’s labyrinth turns out to be but a disguised tree (a synchronic unfolding of a diachronic process) which, of course, a rhizome or a labyrinth of the 3rd type can never become. So, contrary to all that Eco wished to prove, d’Alembert’s labyrinth of knowledge is neither a manifestation of “weak thought par excellence”, nor a form that “made the rhizome thinkable”, nor is it a predecessor of postmodernism. It is a tree, no matter how much obscured or “disfigured” by history ! Therefore, while Eco wanted to prove “that the tree generated again the labyrinth”, he inadvertently succeeded in proving quite the opposite : that the labyrinth generated again the tree, because, in fact, it is a disguised tree !


Apart from this subdued presence under the disguise of the labyrinth of the 2nd type, the tree also appears manifestly in d’Alembert’s Discours in the form of “l’arbre encyclopédique”. Its structure and features are discussed at length over many pages, and, as I have mentioned, its picture is appended to the text. No mention of it in Umberto Eco’s AP ! In DvE Eco says only that : “[…] in one respect, he (d’Alembert) develops the metaphor of the tree ; in another he puts it into question, speaking instead of a world map and a labyrinth”.[58] Then Eco introduces the long quotation from d’Alembert I have also noted earlier, but he refrains from explaining how d’Alembert actually “develops the metaphor of the tree”.

Indeed, if he were confined to solely reading Eco, the reader could not practically realize how important the tree is to d’Alembert and what it looks like. In fact, he is never told that d’Alembert distinguishes, with respect to knowledge, three major branches of the human spirit : memory, reason and imagination. “Ces trois facultés forment d’abord les trois divisions générales de notre système, et les trois objets généraux des connaissances humaines ; l’histoire, qui se rapporte à la mémoire ; la philosophie, qui est le fruit de la raison ; et les beaux-arts, que l’imagination fait naître.”[59]

The reader is not told either that after this basic division which provides the three major genera of knowledge, each branch gets divided again, according to the natural disposition of things :

La distribution générale des êtres en spirituels et en matériels fournit la sous-division de trois branches générales. L’histoire et la philosophie s’occupent également de ces deux espèces d’êtres, et l’imagination ne travaille que d’après les êtres purement matériels. […] À la tête des êtres spirituels est Dieu qui doit tenir le premier rang par sa nature et par le besoin que nous avons de le connaître ; au-dessous de cet Être suprême sont les esprits créés, dont la révélation nous apprend l’existence ; ensuite vient l’homme, qui, composé de deux principes, tient par son âme aux esprits, et par son corps au monde matériel ; et enfin ce vaste univers que nous appelons monde corporel ou la nature. […] L’histoire, en tant qu’elle se rapporte à Dieu, renferme ou la révélation ou la tradition, et se divise, sous ces deux points de vue, en histoire sacrée et en histoire ecclésiastique. L’histoire de l’homme a pour objet ou ses actions ou ses connaissances, et elle est par conséquent civile ou littéraire, c’est-à-dire se partage entre les grandes nations et les grands génies, entre les rois et les gens des lettres, entre les conquérants et les philosophes. Enfin, l’histoire de la nature est celle des productions innombrables qu’on y observe, et forme une quantité de branches presque égale au nombre de ces diverses productions.

To sum up : a) D’Alembert’s encyclopedic order of knowledge relies both on the actual constitution of the epistemic part of the human mind, and on the structure of nature. Botharepresentedasobjectiveandnaturalbytheauthor (a fact which is very consistent with strong thought) and their combination shapes the aspect of the tree of knowledge.

b) D’Alembert adds another similar tree to the tree of knowledge, where the same major threefold division is used to give an accurate account of the social fabric of the “republic of letters” : “La division générale de nos connaissances suivant nos trois facultés a cet avantage qu’elle pourrait fournir aussi les trois divisions du monde littéraire en érudits, philosophes et beaux-esprits : en sorte qu’après avoir formé l’arbre des sciences on pourrait former sur le même plan celui des gens de lettres.”

Obviously d’Alembert aims at a global view of the Universe, since he shows a strong tendency to give a similar account on how mind, nature and society are formed.

c) It is noteworthy that reason holds the central place among the mind’s epistemic faculties described by the tree, and man occupies the central place on the ladder of beings, as the middle term between the realm of the spirit and the realm of the body. While this centrality of both reason and man is an old humanist idea, what matters here is that it refutes Eco’s allegation : “[…] d’Alembert says with great clarity that what an encyclopedia represents has no center,” or “the French Encyclopedia has no center”.[60] On the contrary : as we have seen, both d’Alembert’s encyclopedia (not Eco’s one) and the reality it is supposed to represent do have centers : one is reason within man’s mind, and the other one is man as a whole within the Universe.[61] Therefore, I do not see how one can read an anticipation of the postmodern rhizome in this anthropocentric and rationalistic quality of d’Alembert’s encyclopedism !

d) We remember how Eco subverted Porphyry’s or Aquinas’s strong thought by detaching logic from ontology and metaphysics. Now the Italian philosopher acts similarly with respect to d’Alembert’s Discours. Trying to diminish the epistemic purport of d’Alembert’s tree and perhaps also to explain away his own failure to adequately mention the important presence of the tree, Eco claims in DvE that the tree “[…] has a hypothetical nature : it does not reproduce a presumed structure of the world, but presents itself as the most economic solution with which to confront and resolve a particular problem of the unification of knowledge”.[62]

It is true that d’Alembert is cautious with respect to the absolute epistemic value of his tree. He knows how arbitrary some of these universal constructions may be, due to the scarcity of our knowledge. Yet, it would be totally wrong to cast d’Alembert in the role of a forefather of relativism, by suggesting that to him all worldviews are equally valid, depending on each viewer’s particular perspective.

Maybe his tree — d’Alembert says — was not the best one in itself ; yet, it was reasonably the best one could find for the moment ; any improvement of it is still possible. D’Alembert is ironic towards those scholars who consider their own discipline to be the most important one of all, and likens them to the primitive men who believe that the Universe was made just for themselves. Therefore, one has to become “civilized” — an objective (in his words, “philosophical”) perspective, beyond particular biases, can be reasonably justified : “La prétention de plusieurs de ces savants, envisagée d’un oeil philosophique, trouverait peut-être, même hors de l’amour-propre, d’assez bonnes raisons pour se justifier.”[63]

Certainly, d’Alembert looks for an economic and useful solution of combining the encyclopedic and the genealogical order and of presenting how universal knowledge divides itself into genera and species. Yet, Eco’s allegation that “the tree does not reproduce a presumed structure of the world” has no support whatsoever : it is precisely a presumed structure of the world that d’Alembert’s tree (as once the classical Porphyrian tree) pretends to reproduce. Otherwise, why would d’Alembert bother to create the tree, if he did not believe in the objective value of its divisions ? When someone puts God on top of the “universal ladder”, below whom he ranges the spiritual beings, then man, then the beasts, the plants and the rest of nature, is it possible any longer to claim that this ladder (or tree, for that matter) “does not reproduce a presumed structure of the world” ?


Finally, I wish to broaden a little the scope of this analysis. Clearly, by its fragmentation, multifarious, intricate aspects, lack of linearity, simplicity and evidence, absence of an obvious way out, the labyrinth may constitute an appropriate symbol (or image, model) of postmodern culture and society. The question is, then : what sort of labyrinth are we speaking about, since, according to Eco’s really important distinction, there are two relevant types ? My answer is that, in fact, both types are present in our postmodern culture. Like Hercules at the crossroads, however, I think we have to choose between them. I also think that our choice matters to our destiny.

We have seen that Umberto Eco considers the characteristic image of postmodernism, or of weak thought, etc. to be the labyrinth of the 3rd type, or the rhizome. Moreover, he tried to associate Aristotle, Thomas Aquinas, d’Alembert and the French Encyclopédie to this rhizome-like thought, by claiming that Porphyry’s tree is self-subverting. But, in my opinion, he failed in this attempt. He either fragmented the worldview of some earlier philosophers, thus “discovering” an anti-essentialist quality in them he himself had surreptitiously previously introduced there, or used a false labyrinth of the 3rd type that turned out to be just one of the 2nd type. But, when unwound, the latter becomes a Porphyrian tree. So, eventually, the labyrinth, not the tree, seems to be self-subverting. As for the genuine labyrinth of the 3rd type, it can never become reasonable, as Eco hoped, for it overtly infringes the non-contradiction principle ; one only wonders how a reasonable culture could be modeled on it.

In fact, today’s world is not necessarily rhizomatic. If we realize that our postmodern labyrinth need not be a rhizome, but a maze — still a complex labyrinth at first sight, but one that, if unwound, becomes a tree, perhaps we could lay claim to inheriting Porphyry, Aquinas, d’Alembert, and their likes.

Strange though it may seem, Eco himself may have unwillingly agreed that the Porphyrian tree can take precedence over the rhizomatic net in general, and in postmodernity in particular : in an article written a few years after the publication of the two texts discussed above, he expressed the following view of the essence of postmodernism : “Actually, I believe that postmodernism is not a trend to be chronologically defined, but rather an ideal category or, better still, a Kunstwollen, a way of operating. We could say that every period has its own postmodernism, just as every period would have its own mannerism (and in fact, I wonder if postmodernism is not the modern name for mannerism as metahistorical category.)”[64]

Let us, then, accept his identification of postmodernism with a metahistorical mannerism. On the other hand, we remember that both in AP and DvE, Eco found the labyrinth of the 2nd type or maze precisely in mannerism, in the form of the Irrweg : “The maze is a mannerist invention ; iconologically speaking, it does not appear before late Renaissance.”[65]

Therefore, if the labyrinth of the 2nd type, the Irrweg, or the maze are representative of mannerism, which, in turn, is but a metahistorical postmodernism, then the labyrinth of the 2nd type, and not that of the 3rd type, must be also representative of postmodernism, or at least need not contradict it. So, even according to Eco, postmodernism is not necessarily bound to the relativism of the rhizome, since it can make a more sensible choice : an oriented rationality, still sufficient to privilege some alternatives over others, to accept a certain hierarchy, to look for a center without neglecting the peripheries.The morals of all this would be : the deeper you dive under the surface of our deconstructivist, anti-essentialist ideas, constructs, ways of operating and of thinking, the more chances are that, at the end of the day, you run into the inescapable, old Porphyrian tree. Of course, you can still try to avoid it, or to write an intellectual history where its importance would be diminished as much as possible. However, Eco’s attempt suggests that such efforts are likely to fail. The tree will resurface, even though its genuine, strong thought-based metaphysics was long given up. Maybe the tree is so resilient because, irrespective of this or that metaphysics, our mind basically works by dividing classes, by adding and combining differentiae, so that its chart looks like a tree that relentlessly branches out.[66] Therefore, it seems that this inbuilt “mind game” is being played everywhere, always, and by everybody, including by those who try to forget its existence. Isn’t it, then, the forgetting of it that is to blame ?