To what extent the difference between univocal predication and predication in divinis posed an insurmountable problem is confirmed by the Regulae theologicae of Alain of Lille, in which a distinction is made (somewhat obscurely) between: (i) the transfer of the name and the thing, as in “linea est longa,” where length, which is the property of the body, is said of the line that distinguishes it and makes it possible to call it “long”; (ii) the transfer of the thing, as in “seges est laeta,” where the thing (in this case laetitia or gladness) is attributed to the subject, the cornfield; (iii) the transfer of the name alone, as in “monachus est albus”—in which the white monk is not himself white (we are talking about a white-robed Cistercian). But this is precisely the way we say “Deus est iustus.”
Later in the text, however, Alain admits that God is called just “a causa quia efficit iustum” (“rightly, since he brings about justice”). Here we are close to the position taken by Dionysius, for whom Goodness and Beauty really are divine properties and may be applied to earthly things only insofar as, through participation, they cause something very similar in them. In that case it is not simply a question of transferring the name: indeed it would not even be a metaphor (judging by the above-cited classification).
Since this is not the place to venture into the boundless territory of the discussions on the analogia entis (pointing out the frequently subtle differences between one author and another, right down to the Second Scholasticism of the Counter-Reformation, from Cajetanus to Suarez, we will simply attempt to see what were the basic models for univocal and equivocal discourse that inspired the whole of Scholastic debate. And the fundamental model is always the one derived from Aristotle (see Owens 1951) and from Boethius’s commentary.
The discourse on equivocity is already present in the Metaphysics, where Aristotle discusses how being can be “said in many ways.” After saying that there is a science that considers being in and of itself, when we might have expected his first tentative definition of the object of this science, he repeats as the only possible definition what had appeared in his first book (992b 18) only as a parenthetical observation: “being is said in many ways” (“to de on leghetai men pollachos”)—according to multiple meanings (1003a 33).
In fact, Aristotle reduces these many ways to four. Being is said: (i) as accidental being (this is the being predicated by the copula, whereby we say that a man is white or standing); (ii) as true—it may be true or false that the man is white, or that man is an animal; (iii) as potentiality and act, whereby, while it may not be true that this healthy man is ill right now, he could become ill, and (as we might say today) we can think of a possible world in which it is true that this man is ill; and finally (iv) as ens per se or as substance. However we speak of being, we say it “with reference to a single principle” (1003b 5–6), that is, to the substances: “The first meaning of being is the essence that signifies the substance (semainei ten ousian)” (1028a 14–15).
Is this saying in a number of ways an equivocal way of saying? Aristotle is unclear on this point. In the Categories (1, 1a) he says that we have homonymy or equivocity when entities that require a different definition have a single name in common. The classical example is zoon, used both for an animal and a painting, a homonymy that exists in Greek. It should be said that medieval thinkers, who did not know Greek, failed to grasp this homonymy, thinking that the word animal was used both for the animal and the image of the animal, and that Aristotle gave a broader meaning to equivocity than they did. See, for example, Thomas Aquinas: “Philosophus largo modo accipit aequivoca, secundum quod includant in se analoga” (“The philosopher takes equivocal terms in a broad sense, so they include analogous terms”) (Summa Theologiae I, 13, 10 ad 4).
As Aristotle sees it, we find ourselves faced with an example of accidental equivocation (in the Middle Ages they would have said it was due to penuria nominum). We have synonymity or univocality when the term corresponds to a single definition (when, that is, zoon is said of a man or an ox). And finally, we have paronymity when things are designated by the same term but with a different grammatical ending (“the grammarian” [grammatico] when it stands for “grammar” [grammatica]). Owen (1951) makes it clear that Aristotle considers equivocity or univocality to be properties, not of the term itself, but of the things for which a single term is used.33 Thus, we have univocality when a single term is used for what is expressed by a single definition, and equivocity when we have a single term for two things that correspond to two different definitions.
Different uses of a term are broadly discussed in the Topics (I, 15, 106a 1–8), where Aristotle takes on for the first time the question of a twofold way of employing terms: it is one thing to say that justice and courage are called “good” univocally (because goodness is part of the definition of both) and it is another to say in various ways that what is conducive to health is good. The allusion here is to the original Aristotelian example, widely discussed in the Middle Ages, according to which both people in good health and the medicine conducive to good health, not to mention urine as a sign of good health, are dubbed “healthy.”
In the Nicomachean Ethics (I, 6, 1096b 23–29) the question of why honor, wisdom, and pleasure are called “goods” comes up again. The three things are different, and yet the use of the term is not an example of casual equivocation. Are they called “good” because they depend upon a single cause (“aph’enos”) or because they are directed toward the same end or good (“pros hen”)? Or is it by analogy, following the example of sight that is good for the body just as the intellect is for the soul? Here Aristotle clearly distinguishes the first case from true analogy, which sets up a proportion among four terms.34
In Boethius’s Latin translation of Porphyry’s Isagoge, “aph’enos” and “pros hen” are rendered respectively as “ab uno” (the term “medical” used both for the doctor himself and for the doctor’s potions and instruments) and “ad unum” (the classical example of “healthy” said of the body, the medicine, and the urine). Clearly, however, the first example is a relatively weak one, since it could be reduced to a case of paronymy. In fact the concept that remains central in Aristotle is that of pros hen. Briefly put, to be named for the cause one proceeds from or for the end toward which one tends is to all intents and purposes the same thing (we could say that the relationship is based on a common cause, whether it be efficient or final). What we have, then, are two forms of equivocity, pros hen, which the scholastic tradition will dub analogy of proportion (and, in the case of Cajetanus, of attribution), and that by analogy, which the scholastic tradition will dub analogy of proportionality. For convenience sake, from now on we will use the two terms attribution, which for Aristotle was not a form of analogy, and proportionality, which for Aristotle was the only form of analogy.
Aristotle explains the attribution in the Metaphysics (K. 3, 1060b 36–1061a 7) where he takes as examples of speaking “in several ways” the adjectives medical and healthy: they are used in reference to (pros) the same thing: a medical discourse and an instrument are both called “medical” because the medical discourse proceeds from medical science and the instrument is useful to that science; in like manner, things that are signs or causes of health are termed “healthy.” Now, health is something that is only found in a body and is not present in the color of the urine or that of the medicine (we ought to speak, then, of a patently equivocal situation in which a single term is referred to things that have different definitions). Both the urine and the medicine, however, refer to health. Just as the term being is used in various senses but with reference to one central idea (pros hen), and is therefore not equivocal, the same goes for the term “healthy.” Both express a common notion (legonthai kath’en).
Attribution is a relationship involving two terms: medicine is healthy because it causes health, and we cannot say that medicine is to the sick body as health is to the healthy body. The case of analogy is different. Here four terms are required, as we are also reminded in the Poetics and the Rhetoric. The stone is shameless because it is to Sisyphus as the shameless man is to his victim (Rhetoric, III, 11, 1412a 5, in Bollingen ed., p. 2253). Now, whereas the examples of attribution are always given as instances of the stereotyped use of language (healthy medicine, healthy urine), for Aristotle the analogy is an instrument of knowledge, and he makes use of it, when it serves him, in his books on nature too. “The underlying nature can be known by analogy” (Physics I, 7, 191a, in Bollingen ed., p. 326).
At this point let us reconsider the very nature of metaphor.
