27Issue X ◆ Spring 2023 How Can We Reach the True Definition of Something δι ά νο ια HOW CAN WE REACH THE TRUE DEFINITION OF SOMETHING? Essence, Definition, and Teleology in Aristole's Metaphysics MINJUN LEE “!e ultimate value of life depends upon awareness and the power of contemplation rather than upon mere survival.” -Aristotle INTRODUCTION What is wisdom (sophia)? In Metaphysics, Aristotle says, “Clearly, wisdom is knowledge of certain principles and causes (ἡ σοφία περί τινας ἀρχὰς καὶ αἰτίας ἐστὶν ἐπιστήμη, δῆλον)” (982a2). 1 For him, the task of Metaphysics is investigating being qua being, the principles and causes of being.2 !e inquiry into being qua being signi"es the question of what a being is. What a being is and what a substance is are the same: “Namely, what is being? is just the question, What is substance?” (1028b3).3 Aristotle believes that a substance is equal to an essence: “the essence, the account of which is a de"nition, is said to be each thing’s substance” (1017b22). !e essence and the de"nition (horismos) are one in some sense: “the de"nition is the account of the essence” (1031a11). If the essence of a thing X is p, then the de"nition of X is the statement “X is p.” !us, reaching the true de"nition ! "is citation from Metaphysics refers to the Loeb translation. # Metaphysics 1003a20-27 $ All citations here and throughout this paper refer to the Reeve translation; see appended bibliography. 28 Dianoia: The Undergraduate Philosophy Journal of Boston College of something is identical to knowing what something is and can be an answer to the question of Metaphysics. Nevertheless, there is a puzzle with Aristotle’s method of reaching the true de"nition of something in Metaphysics. He approaches the de"nition of something by dividing genera and "nding di#erentiae. However, if we follow Aristotle’s system to reach the de"nition of something, we face the moment when it is questionable whether the de"nition by means of genera and di#erentia is the true de"nition. For instance, Aristotle gives a de"nition of a human: “A human is a featherless, two- footed animal.”4 Since the de"nition of something is the account of its essence, if the account “a human is a featherless, two-footed animal” is the true de"nition of a human, the essence of a human is nothing but ‘featherless and two-footed.’ !is is because the essence means “what something is” (1030a3). Does such a de"nition truly capture the essence of a human being what a human is? Although a human is the only featherless and two-footed living creature, this does not seem to be the true de"nition of a human. We know that what a human is goes beyond this de"nition by virtue of being a human. Living a human life is more valuable than just surviving as one of the animals. !erefore, this de"nition is the mere taxonomic de"nition. !is de"nition does not express a vivid human life. Hence, we should know how to "nd the true de"nition of something in order for us not to remain as a merely featherless, two-footed animal. Unfortunately, Aristotle does not give us any suggestion of how we can overcome this issue. Unless we know the solution to surmount this problem with Aristotle’s method, we may not reach the true de"nition of something. If we cannot reach the true de"nition of something, then we cannot know its true essence. !is is a signi"cant problem for Aristotle, who seeks knowledge of what it is in Metaphysics. However, there is a way of reconciling the method of reaching a taxonomic de"nition and a true de"nition. !is is the aim of this paper. We will not dismiss Aristotle’s method of dividing genera and "nding di#erentia. Instead, we will interpret the true meaning of the ultimate di#erentia in this paper. !is interpretation of the meaning of the ultimate di#erentia will guide us towards the true de"nition of something. Hence, the ultimate goal of this project is to "nd the true meaning of the ultimate di#erentia of something, supplement Aristotle’s method of division, complete his un"nished project, and reach its true de"nition. OVERVIEW In order to achieve this aim, we will proceed in three parts. In Part 1, we will investigate what a de"nition is and how Aristotle approaches the de"nition by means of genera and di#erentiae. Using this method, Aristotle de"nes a human as ‘a featherless, two- footed animal.’ However, it is questionable whether this is the true de"nition of a human due to two reasons. !erefore, we will articulate why this is not the true de"nition of a human and begin to look for a solution. In Part 2, we will attempt % Metaphysics 1037b34 29Issue X ◆ Spring 2023 How Can We Reach the True Definition of Something to rectify this issue by showing that the ultimate di#erentia (teleutaia! diaphora) of something, is, in fact, the same as the end (telos), which lies at the heart Aristotle’s theory. In Part 3, we will attempt to reach the true de"nition of something by reconciling Aristotle’s method with its ultimate di#erentia (telos). PART !: DEFINITION OF GENERA AND DIFFERENTIA What is a de"nition? !e de"nition of something is the account of its essence. Aristotle says, “For the essence is just what something is (ὅπερ γάρ τί ἐστι τὸ τί ἦν εἶναι)” (1030a3). !us, if we ask the question “what is a human?” then the answer to this question would require the essence of a human. Nevertheless, what does he mean by “what something is?” Let us look at another explanation for the essence to have a better grasp of it. Aristotle describes the essence as what it is said to be intrinsically: !e essence of each thing is what it is said to be intrinsically. For the being for you is not the being for musical. For you are not intrinsically musical. [Your essence], therefore, is what you are [said to be] intrinsically. (1029b14-15) You can be musical. However, you do not need to be musical. You can still be you without being musical. Being musical is not necessary for being you. !erefore, it is accidental. However, let us assume that there is some characteristic p essential to being X. Since to be p is necessary for X, X cannot be X without it. Hence, the essence of each thing is that which is necessary to being it. !us, it appears that the de"nition of a thing is the account of what is necessary to being it. !en, what is the account (logos)? !e Greek word ‘λόγος (logos)’ means speech or thought. !us, the de"nition of something is the speech or thought of its essence. However, what we want to know is the essence of something (or what something is), since the main task of Metaphysics is the investigation of what something is. In that case, why do we need speech? !e reason may be that the essence of a thing does not belong to us; it belongs to the thing itself. !us, if we want to relate to and understand a thing, we need some mediator between it and us. It is the speech (logos) that belongs to us and expresses our understanding of it.5 !us, the de"nition belongs to us since a de"nition is a kind of an account. We come to the essence by means of a logical procedure of our language. And since an account consists of a subject and a predicate that states an attribute of the subject, the de"nition also has a linguistic structure composed of a subject and a predicate. Hence, since the de"nition of a $ In On the Soul, Aristotle explains in detail how we cognize and understand a sensible object logico-linguistically. When we perceive (aisthanesthai) a sensible object, imagination (phantasia) works. Because of imagination, a mental image (phantasma), the sensible form of a sensible object, is presented to us (427b20). And then, our thinking capacity, the mind (nous), thinks this mental image. !inking (noe") is the process in which the mind in the active sense makes the mind in the passive sense actually identical with the objects of thought (430a14-17). When we think a thing, we make the notion of it. When we try to understand an object, we combine notions and make an account such as “S is P.” !erefore, our understanding of the world is intertwined with our account. !e account of something expresses our understanding of it. (!is footnote refers to the Loeb translation.) 30 Dianoia: The Undergraduate Philosophy Journal of Boston College thing is the account of its essence, the de"nition is the linguistic expression of that which is necessary to its being. If the de"nition consists of a subject and a predicate, what kind of thing can be the subject of a de"nition? In other words, what can we de"ne? In Metaphysics, Aristotle deals only with substance (ousia) for the de"nition of something: “It is clear, therefore, that only of substance is there a de"nition” (1031a1). !erefore, only substance can be situated in the subject of the de"nition. What, then, is a substance?6 In his early book Categories, Aristotle divides a substance into two groups: particular objects and species.7 Individual things (tode ti; a “this something”), such as an individual man, are substances. And species (a human) and the genera of these species (an animal) are also substances. !is shows us that Aristotle thinks that both a particular substance (say, Socrates) and a species (say, a human) or the genus of a species (say, an animal) can be a substance in a broad sense. Nevertheless, Aristotle thinks that not all substances are proper candidates for the subject of their de"nitions. Of substances, we can only de"ne a species. !e de"nition is the account of the essence. Only things that are species of a genus have an essence: “Hence the essence will belong to things that are species of a genus and to nothing else” (1030a11-12). !erefore, only the species of a genus have their de"nitions.8 How, then, does Aristotle express the essence of something in the predicate of its de"nition? !e subject of the de"nition of something is a species, so the predicate of its de"nition must be its genus and its di#erentiae. !is is made clear by the fact that he says a species is a genus plus di#erentiae: “the species are composed of the genus and the di#erentiae” (1057b7). Undoubtedly, he expresses the account of its essence with its genus and its di#erentia: % What is a substance? !is is an extremely complicated question to answer since his explanations of a primary substance and a second- ary substance in Categories and Metaphysics are di#erent. First, concerning a primary substance, in Categories, Aristotle explains that primary substances are particular objects (tode ti; a this something). In contrast, Aristotle says that the what-it-is (to ti esti) is primary in Book Z1 of Metaphysics (1027a14). Why are they di#erent? !e simplest hypothesis I can make is that, in Categories, he thinks that tode ti is primary, but in Metaphysics, he divides tode ti into matter (hyl#) and form (eidos). By dividing tode ti into matter (hyl#) and form (eidos), he thinks the what-it-is (to ti esti) is primary. Second, pertaining to a secondary substance, in Categories, Aristotle says that a species or the genera of a species are secondary. But in Metaphysics, species are regarded as form (eidos). However, he thinks that form is primary in Metaphysics. !ere would be more complexities related to what a substance is. Nevertheless, this is not our main project in this paper. What we want to know here is what can have a de"nition. !erefore, with the question of what a substance is, we will merely think that a substance is that which exists (being) such as 1) movable and perishable things in the sub-lunar level (animals or cups), 2) movable and eternal things (planets), and 3) something immovable and eternal (the prime mover). (1069a29-33, Metaphysics) & Categories 2a13-18. ' Why does Aristotle think that there is no de"nition of a particular and perceptible substance? !ere are two reasons. First, an account does not admit the generation or destruction of something. (1039b23-30, Metaphysics) Perceptible and particular substances have matter. Substances having matter can come to be and pass away. However, an account only outlines whether something is or is not. !erefore, there is no de"nition of perceptible and particular substances. For instance, Socrates is a particular perceptible substance because Socrates has his body, which is matter. !erefore, Socrates is coming to be and passing away. We cannot de"ne Socrates qua Socrates. Although we can de"ne Socrates qua man, this is not a particular de"nition but his species de"nition. Second, a subject itself should not be present in the predicate of its de"nition. (1029b18-20, Metaphysics) !e predicate of a de"nition should explain its sub- ject without using the subject in the predicate. For example, we should not say that the de"nition of a cup is “a cup is a cup that is . . .” However, if we attempt to de"ne a particular object, we will violate this rule. For instance, let us try to reach the de"nition of this cup. Its de"nition would be something like “this cup is a cup which is here.” !is disobeys the rule that a subject itself should not be present in the predicate of its de"nition. In addition, Aristotle also excludes the possibility of the de"nition of the genus of a species since the genus of a species does not have the essence. Nonetheless, we can see that we de"ne an animal as a perceptual living thing, for instance. It seems that, for Aristotle, we can give a de"nition of genus, but when we do this, we do not truly work on the question of what it is. 31Issue X ◆ Spring 2023 How Can We Reach the True Definition of Something We should "rst investigate de"nitions that are by division. For there is nothing else in the de"nition except the genus that is mentioned "rst and the di#erentiae; the other genera are in fact the "rst one along with the di#erentiae combined with it. (1037b28-30) By dividing genera, Aristotle "nds the de"nition of something. First, he discovers the genus of something and then "nds the di#erentiae combined with the genus. For instance, Aristotle o#ers “a human is a featherless, two-footed animal” as a de"nition.9 In this de"nition, a species (a human) is the subject, and the genus (animal) and the di#erentiae ‘two-footed’ and ‘featherless’ are predicated of it. Nonetheless, before we try to follow how Aristotle reaches this de"nition, we should understand what a genus and a di#erentia are. !e genus of something is the common thing of what are distinct in species: What is distinct in species is distinct from something, in something, and this latter thing must belong to both—for example, if an animal is distinct in species [from another], then, both are animals. Hence [two] things that are distinct in species must be in the same genus. For this is the sort of thing I call a genus, that by reference to which both things are said to be one and the same, and which is not coincidentally di#erentiated, whether as matter or otherwise. (1057b34-1058a1) If we interpret the "rst sentence as “what is distinct in species (A) is distinct from something (B), in something (C),” we know that A and B are distinct in species, but both A and B belong to C. !en, C is the genus of A and B. For example, a human (A) and a horse (B) are distinct in species. However, the common thing they share is their genus (C). Both a human and a horse belong to the genus of animals (C). !erefore, animal (C) is the genus of a human (A) and a horse (B). In addition, a di#erentia is what makes the di#erence between A and B: !is di#erentia, therefore, will be a contrariety (as is also clear from induction). For all things are divided by opposites, and it has been shown that contraries are in the same genus. For contrariety was seen to be complete di#erence, and all di#erence in species is di#erence from something, in something, so that this latter thing is the same for both and is their genus . . . Hence the di#erentia is a contrariety. (1058a8-16) If we consider the di#erentia ‘two-footed,’ then between a human and a horse, a human is two-footed, but a horse is not. !erefore, this di#erentia makes a distinction between them within the genus “animal.” ( Metaphysics 1037b12 32 Dianoia: The Undergraduate Philosophy Journal of Boston College So far, we have investigated what a de"nition is and what we can de"ne in Metaphysics. !e de"nition of something is the account of its essence. !e subject of a de"nition is a species, and the predicate expresses its essence. Aristotle thinks that he can logico-linguistically express the essence of a species with its genus and its di#erentia and reach its de"nition. He does this by the method of division and classi"cation.10 He proceeds from genus to species by dividing genera and "nding di#erentiae. Accordingly, let us attempt to "nd the de"nition of a human using his method in order to understand the problem with his method. !e initial task is to "nd its genus. Of things that exist in the universe, some are natural, and others are arti"cial. A human certainly belongs to the natural things category. Aristotle says that natural things are simple bodies, such as earth, "re, water, and air, and living bodies, such as plants and animals.11 Among natural things, a human is an animal. !erefore, a human is placed under the genus of animals. Since the genus of animals is the proximate genus of a human, we know the genus of a human. However, under the genus of animals, there are innumerable species (say, a horse, a bird, a dog, a whale, etc.). !us, to proceed from genus to species, we should "nd the di#erentiae of a human. Among animals, some are ‘footed,’ and others are not. A human belongs to footed animals. Of footed animals, some are ‘two-footed,’ and others are not (say, ‘four-footed’). A human has two feet. !erefore, a human is a two-footed animal. Nonetheless, there is still an abundance of two-footed animals: all types of birds, as well as humans, qualify as two-footed animals. We require more di#erentiae. How about ‘feathered? !e contrariety of ‘feathered’ is ‘featherless.’ A human does not have feathers. !erefore, a human is a featherless, two-footed animal. Is there another featherless, two-footed animal? If so, we should "nd another di#erentia. However, a human is the only featherless, two-footed animal. Hence, this is the de"nition of a human by means of genera. !e diagram below shows the journey of this division. 10 1037b29 11 Physics 192b9-10 33Issue X ◆ Spring 2023 How Can We Reach the True Definition of Something We have followed the way in which Aristotle expresses the essence of a species by "nding the most speci"c genus and di#erentiae. As a result, we have reached the de"nition of a human: A human is a featherless, two-footed animal. !is de"nition sounds plausible. No one would deny it. !e di#erentiae ‘featherless’12 and ‘two-footed’ are unquestionably essential characteristics of a human. A human is intrinsically ‘two-footed’ and ‘featherless.’ A human is the only animal having the di#erentiae ‘featherless’ and ‘two-footed’ together. !erefore, this de"nition is exclusive to a human being.13 However, is this de"nition satisfactory? !e de"nition of something is the account of its essence. Does this de"nition capture the essence of a human quite well? We can be satis"ed with this de"nition if we regard ourselves nothing but featherless, two-footed animals! However, we are not satis"ed with the de"nition “a human is a featherless, two-footed animal” for two reasons. First, the combination of the di#erentiae ‘featherless’ and ‘two-footed’ are not what makes us humans in a positive sense even though these di#erentiae may set us apart from all other animals. In other words, these qualities express not what we ourselves are intrinsically but what other animals are not. Aristotle says that the essence (to ti #n einai; ‘the-what-it-was-to-be’) is the cause: “It is evident, accordingly, that we are inquiring into the cause. !is is the essence, logico-linguistically (φανερὸν τοίνυν ὅτι ζητεῖ τὸ αἴτιον (τοῦτο δ᾿ ἐστὶ τὸ τί ἦν εἶναι, ὡς εἰπεῖν λογικῶς))” (1041a27). What is the cause of a thing X? !is question is the same question as “what causes X to be X?” !e answer is the essence of X. Since the essence of X belongs to X, X is X. If the account “a human is a featherless, two-footed animal” is the true de"nition of a human, then the essence of a human is the combination of the di#erentiae ‘featherless’ and ‘two-footed.’ It means that because of these di#erentiae ‘featherless’ and ‘two-footed,’ we are humans. Is it because “featherlessness” and “two-footedness” belong to me that I am a human being? De"nitely not; we know that what a human is goes beyond this de"nition. What is it to be a human? To live a human life is not just to exist as a creature which has no feathers and has two legs. Although the di#erentiae ‘featherless’ and ‘two-footed’ seem to be essential components for a human because a human can move owing to two feet, these two essential qualities do not seem to make a human a human. How can we capture what it is to be a human in the de"nition of a human that Aristotle suggests? Without capturing the essence of something, it is hard to say that we know what it is. Knowing what it is means that we know its essence and have reached its true de"nition. !erefore, if the di#erentiae of something do not capture its essence, it is unlikely that we know what it is and have reached its true de"nition. 12 It is strange to say that ‘featherless’ is essential for a human being. How can we talk about some non-existent qualities? We should say what a human has instead of saying what a human does not have. We will look into this problem in a few paragraphs. 13 In fact, there are some other ‘two-footed, featherless animals,’ such as kangaroos and Tyrannosaurus Rex, although I assume that Aristotle is not aware of them in his life, unfortunately. 34 Dianoia: The Undergraduate Philosophy Journal of Boston College !e second reason why the de"nition reached by genus and di#erentiae is insu)cient is that the essence of something cannot be changeable, but the combination of essential di#erentiae seems subject to change. !ere are still copious di#erentiae that are essential characteristics of a human. A human is a ‘vertebrate.’ A human is ‘warm- blooded.’ A human is ‘two-handed.’ If we begin the task of de"ning a human with another di#erentia, we will reach another de"nition of a human being. For instance, let us try to "nd the de"nition of a human with the di#erentia ‘vertebrate.’ We know the genus of a human is an animal. We can divide animals into ‘vertebrates’ and ‘invertebrates.’ A human is a ‘vertebrate.’ !ere are innumerable vertebrate animals. We can break them down into ‘warm-blooded’ and ‘cold-blooded.’ Since a human is ‘warm-blooded,’ the tentative de"nition of a human is a warm-blooded, vertebrate animal. However, we know that there are a lot of warm-blooded, vertebrate animals. From this, we can add the previous example—‘featherless’ and ‘two-footed’—to the de"nition we have reached in this paragraph. !en, at the end of this process, the de"nition of a human is a featherless, two-footed, warm-blooded, vertebrate animal. !is shows that we will sometimes de"ne a human as a featherless, two-footed animal, and at other times we will de"ne a human as a featherless, two-footed, warm- blooded, vertebrate animal. Hence, the de"nition of something changes whenever we "nd another di#erentia. Indeed, Aristotle himself is aware of the problem with his dichotomous method in his book Parts of Animals: Now if man was nothing more than a cleft-footed animal, this single di#erentia would duly represent his essence. But seeing that this is not the case, more di#erentiae than this one will necessarily be required to de"ne him; and these cannot come under one division; for each single branch of a dichotomy ends in a single di#erentia, and cannot possibly include several di#erentiae belonging to one and the same animal. It is impossible then to reach any of the ultimate animal forms by dichotomous division. (644a7- 13, Parts of Animals) !e di#erentiae can be changed because one and the same genus can be dichotomously divided in many di#erent ways. He thinks that there is no single de"nition of an animal species. How can the essence of something change depending on the method of di#erentiation? How can sometimes ‘featherless and two-footed’ make a human be a human and other times ‘featherless, two-footed, warm-blooded, vertebrate’ make a human be a human? If the essence is unchangeable, the essential di#erentia should also be unchangeable. However, the combination of essential di#erentiae seems to be changeable insofar as we can swap out one di#erentia for another. Why does this problem occur? We do not have a way to guide us among these decisions. We do not have a basis from which to decide because they both capture essential qualities. !erefore, even if we follow 35Issue X ◆ Spring 2023 How Can We Reach the True Definition of Something the methodical dichotomous division of the genus, we might run into problems. For example, consider that we want to de"ne a cup. !e genus of a cup is ‘vessel.’ However, both a house and a cup can be considered to be vessels. Now, we need a di#erentia to distinguish them. A house is ‘doored.’ In contrast, a cup is ‘doorless.’ According to Aristotle’s method, we "nd ourselves in a position of saying that a cup is a doorless vessel. We know that a door never has anything to do with a cup. Similarly, though it is supposedly a “featherless, two-footed animal,” a feather does not have anything to do with a human at all. Why do we consider some feature that does not apply to us as essential? How can something that we do not have make us what we are? By following the method of di#erentiation, we "nd ourselves including in the de"nition essential qualities that are lacking in the species and that have no relevance to a human and a cup. Hence, even in the most careful application of Aristotle’s method, we still reach a de"nition that includes arbitrarily chosen di#erentiae. So far, we have seen the reasons why the account “a human is a featherless, two- footed animal” is not the true de"nition of a human. !e combination of the essential di#erentiae of X might not make X be X. It is true that the combination of the essential di#erentiae of X may tell us that X is di#erent from any others due to the combination of the essential di#erentiae of X. However, it does not mean that these qualities signify what X itself is intrinsically. It only tells us what others are not. In addition, the arbitrariness of this method makes it vulnerable for us to reach the true de"nition. Unless we know the essence of something, it is unlikely that we reach the true de"nition of something. We might have to be satis"ed with a mere taxonomic de"nition: “what de"nitions are like” (1038a35) while we pretend to think we know the essence of something. !erefore, in Part 2, we will "nd a solution to overcome this problem. PART ": THE ULTIMATE DIFFERENTIA #TELEUTAIA DIAPHORA$ IS THE END #TELOS$ In Part 1, we attempted to understand what a de"nition is, what we can de"ne, and how Aristotle reaches the de"nition of something by the method of division. However, this method is not enough to capture the essence of something. To overcome this problem and reach the true de"nition of something, we need to consider the ultimate di#erentia (teleutaia diaphora). As Aristotle presents it, the ultimate di#erentia is the one that cannot be further divided. For instance, when we de"ne a human as a featherless, two-footed animal, we divide animals with the "rst di#erentia ‘two- footed’ and the second one ‘featherless.’ !en, we reach a point in the procedure at which it becomes impossible. Nevertheless, it seems to me that the more signi"cant feature of the ultimate di#erentia is its aptitude for capturing the essence of a thing. 36 Dianoia: The Undergraduate Philosophy Journal of Boston College !erefore, the goal of Part 2 is to investigate how to arrive at an ultimate di#erentia that is not arbitrary but that reliably captures the essence of the thing. If we know the ultimate di#erentia of something, we will reach its satisfactory de"nition. Aristotle thinks this is the correct procedure to follow: “!us it is evident that the de"nition is the account composed of the di#erentiae, or, if it is in accord with the correct procedure, the ultimate one” (1038a28-30). Without knowing the ultimate di#erentia of something, we might get lost in the labyrinth of the di#erentiae and not be able to "nd its true de"nition. Aristotle suggests that the ultimate di#erentia will be the form and the substance: “If, then, we take a di#erentia of a di#erentia, one di#erentia—the ultimate one (teleutaia diaphora)—will be the form (eidos) and the substance (ousia)” (1038a24- 25). !is is the only clue we can use in order for us to reach the true de"nition of something. Hence, the aim of Part 2 is to understand that the ultimate di#erentia of something is its end (telos) by utilizing this hint. Because Aristotle says that the ultimate di#erentia is the form and the substance, the exploration of the form (eidos) and substance (ousia) is our primary task.14 !en, what are the form and the substance?15 Aristotle thinks that form and the substance are the same: “And by form I mean the essence of each thing and the primary substance” (1032b1). And we have seen that the primary substance is the what-it-is.16 !e essence of each thing is what it is. !erefore, the form is the same as the substance. In addition, he says that the form and the substance are the activity: “So it is evident that the substance and the form are activity (ὥστε φανερὸν ὅτι ἡ οὐσία καὶ τὸ εἶδος ἐνέργειά ἐστιν)” (1050b1). !erefore, since the ultimate di#erentia is the same as the form and the substance, and the form and the substance are the same as the activity, the ultimate di#erentia will express the activity of the thing de"ned. !en, what is the activity (energeia) of something? Aristotle says, “the activity is the end (τέλος δ᾿ ἡ ἐνέργεια)” (1050a9). And the end is the characteristic activity of a thing. It is that activity for-the-sake-of-which something is, without which it would not be what it is. !en what is the end (telos), or that for-the-sake-of- which? 14 Indeed, this direction is reasonable. !e de"nition is the account of the essence. In fact, Aristotle says that the essence belongs to the form and the activation: “Since the essence belongs to the form and the activation (τὸ γὰρ τί ἦν εἶναι τῷ εἴδει καὶ τῇ ἐνεργείᾳ ὑπάρχει)» (1043b1). !us, if we know the form and the activation of something, we immediately come to know its essence. Since the ultimate di#erentia of something is its form and its substance, and since our project aims to know what the ultimate di#erentia of something is, this is the correct path toward its true de"nition to investigate the form, the activation, and the substance. 15 We do not undertake a deep investigation of the meanings of the form (eidos) and the substance (ousia). Remember that Part 2 of this paper aims to understand that the ultimate di#erentia (teleutaia diaphora) and the end (telos) are the same. !e deep exploration of these terms will distract the big picture. 16 1028a14. 37Issue X ◆ Spring 2023 How Can We Reach the True Definition of Something !e end, and this is the for-the-sake-of-which—for example, of taking walks health is the end. For why does [he] take walks? “In order that he may be healthy,” we say. And in speaking that way we think we have presented the cause. Also, anything, then, that comes to be as an intermediate means to the end, when something else has started the movement: for example, in the case of health, making thin, purging, drugs, or instruments, since all these are for the sake of the end, although they di#er from each other in that some are instruments and others works. (1013a33-1013b3) !e end of something or some action is that for-the-sake-of-which. Why does he take a walk? Or what is the function of him taking a walk? !e end of taking a walk is health. Why does he make himself thin? Or what is the purpose of making himself thin? To be healthy. Why does he take drugs? To be healthy. All the instruments and actions here have an end, which is health. !is is because when we ask a question about instruments or works with the interrogative ‘why,’ one type of answers uses “for.”17 Why do you eat? For health. Why do you work? For making money or for serving the society. Hence, since the ultimate di#erentia is the activity, and since the activity and the end are the same, the ultimate di#erentia is the end. For instance, let us consider a cup. !e end of a cup is to contain liquid. !en, the ultimate di#erentia of a cup is ‘containing liquid’ and ‘containing non-liquid (say, solids).’ We know that a cup is for containing liquid. !erefore, the ultimate di#erentia of a cup is its end. So far, we have demonstrated that the ultimate di#erentia (teleutaia diaphora) of something expresses its end (telos). In order to grasp the entire demonstration in the simplest way, let us look at its summary in a Euclidean way: “!e ultimate di#erentia (teleutaia diaphora) is the form (eidos) and the substance (ousia)” (1038a25). “!e substance and the form are activity (energeia)” (1050b1). “!e activity (energeia) is the end (telos)” (1050a9). !e ultimate di#erentia (teleutaia diaphora) is the end (telos). !is shows us that Aristotle’s terms ‘the ultimate di#erentia (teleutaia diaphora)’, ‘the form (eidos)’, ‘the substance (ousia)’, ‘the activity (energeia)’, ‘the end (telos)’ are the same. !erefore, the ultimate di#erentia of something is the same as its end. At the end of Part 1 of this paper, we have seen the necessity of overcoming the problem with Aristotle’s method. Hence, we have looked for the possibility to surmount this issue in Part 2. Finding a solution begins with the fact that the ultimate di#erentia of something is the same as its form and its substance (or essence).18 We 17 Physics 198a15-2 18 It is safe to say that the essence and the substance are the same in that both signify “what something is.” 38 Dianoia: The Undergraduate Philosophy Journal of Boston College have "gured out that the ultimate di#erentia of something is eventually the same as its end (telos). Indeed, Aristotle claims that the essence of something and its end are the same: “What a thing is and its purpose are the same (τὸ μὲν γὰρ τί ἐστι καὶ τὸ οὗ ἕνεκα ἕν ἐστι; the literal translation is “the essence and for-the-sake-of-which are the same”)” (198a25, Physics). Now, the procedure by genus and di#erentia that leads to the de"nition “a human is a featherless, two-footed animal” is like the process that we would use. However, this is not the complete version of this process. Indeed, Aristotle seems to acknowledge that this is not the perfect procedure for the true de"nition of something at the end of Z 12: “Where de"nitions by division are concerned, then, let this much su)ce as a "rst statement as to what they are like” (1038a35). Here, Aristotle seems to be suggesting that though this de"nition serves as an example as to how one might proceed by division, he is not necessarily asserting the given de"nition to be complete. Nevertheless, we will not dismiss this procedure entirely. Instead, since we now know that the ultimate di#erentia of something is its end, we will rely on a method like genus and di#erentiae, but we will involve a teleological ultimate di#erentia.19 !erefore, let us continue on to see whether we can fully capture the essence by "nding the ultimate di#erentia: that is, telos. PART %: THE DEFINITION OF MEANS OF GENERA AND THE END #TELOS$ In Part 1, we "gured out the reason why we cannot reach the true de"nition of something. !e cause of the problem is that we bifurcate the genera and species without knowing the ultimate di#erentia of something. !erefore, in Part 2, we have made an e#ort to know what the ultimate di#erentia of something is. !e answer is that the ultimate di#erentia of something is its end. !erefore, "nding out the ultimate di#erentia involves not just "nding a feature that obeys contraries, but "nding a purposive division under the genus. Now, we should assess whether we can reach the true de"nition of something when we know its end. !is is the aim of Part 3. Let us imagine an example. Your friend asks, “What is the purpose of a house?” We may say that the purpose of a house is to shelter property and bodies. !is is the activity of a house: !at is why of [1] those who give de"nitions, . . . [2] !ose, on the other hand, who propose that it is a receptacle to shelter property and bodies, or something else of that sort, are speaking of the activation (energeia). . . For 19 See Page 18 or 1038a28-30. 39Issue X ◆ Spring 2023 How Can We Reach the True Definition of Something it seems that [2] the account that it is given in terms of the di#erentiae is of the form (eidos) and the activation (energeia). (1043a13-19) !e activity of a house is the same as its purpose. Since we know the purpose of a house, we know what a house is, and we can reach its true de"nition: “A house is a receptacle (or vessel) to shelter property and bodies.” !erefore, if we know a thing’s end, we can reach its true de"nition. However, as stated above, this does not reject Aristotle’s method of division and classi"cation. !e only di#erence is that we do not divide the genus with arbitrary bifurcations. We add the ultimate teleological di#erentia to his method. For example, let us de"ne a doctor with Aristotle’s method and the ultimate di#erentia. !e end of a doctor is to cure patients. With the method of genus and di#erentia, the genus of a doctor is a profession. !e ultimate di#erentia of a doctor is to cure or not to cure since this is the end of a doctor. !erefore, the true de"nition of a doctor is that a doctor is a professional who cures patients. Likewise, let us de"ne a cup. !e genus of a cup is a vessel. !is is because there are many types of vessels, so that vessel is not a species but the genus of a cup. Since we know the genus of a cup, if we know its ultimate di#erentia, we can reach its true de"nition. !e ultimate di#erentia (the end) of a cup is to contain liquid. !us, its true de"nition is a vessel that contains liquid. So far, all the examples we have examined are artefacts. Since we create them with our craft, we certainly know the end of them. We are the e)cient cause of arti"cial things. We are builders who build a house or a cup. If we do not know the purpose of a house or a cup, it is impossible to make them. Hence, we can reach the true de"nition of arti"cial things since we know their purposes. Nevertheless, let us "nally attempt to reach the de"nition of a human. If we know the end of a human, then we can reach its true de"nition. What is the end of a human? Let us attempt to "nd it in a two-fold manner if we can. On the one hand, Aristotle suggests that knowledge is our end: “All humans by nature desire to know” (980a21). !is is possible because a human has reason (logos). !is is the most fundamental di#erence between humans and other living creatures: “Man alone among the animals has speech (λόγον δὲ μόνον ἄνθρωπος ἔχει τῶν ζῴων)” (1253a10, Politics). A human can think (noe"), understand (phrone"), and judge (krin"). !anks to this faculty, we naturally pursue knowledge. What do we want to know? We experience the world and understand it. However, a human’s desire to know does not merely signify knowledge of phenomena–that is, knowledge that “the ball I grab falls down to the ground when I unfold my hand” or “the sky is blue.” We want to know “why?” What causes these things? What is the cause of phenomena? !e primary starting-points and causes are what we want to know. !is is wisdom, as stated above. Hence, all human beings think–no#sis–to know. !is is our activity (energeia). !is is our goal (telos). !erefore, a human being is for thinking. On the other hand, in Nicomachean Ethics, Aristotle suggests that happiness is the "nal end of a human: “So happiness appears to be something complete and self- su)cient, it being an end of our actions” (1097b20). In Book 1 of Nicomachean Ethics, Aristotle thinks that happiness is an activity of soul in accord with virtue: 40 Dianoia: The Undergraduate Philosophy Journal of Boston College …if this is so, then the human good becomes an activity of soul in accord with virtue, and if there are several virtues, then in accord with the best and most complete one (εἰ δὴ οὕτως, ἀνθρώπου δὲ τίθεμεν ἔργον ζωήν τινα, ταύτην δὲ ψυχῆς ἐνέργειαν καὶ πράξεις μετὰ λόγου, σπουδαίου δ᾿ ἀνδρὸς εὖ ταῦτα καὶ καλῶς, ἕκαστον δ᾿εὖ κατὰ τὴν οἰκείαν ἀρετὴν ἀποτελεῖται). (1098a16-18, Nicomachean Ethics) Happiness is an activity of soul in accord with virtue. To achieve happiness, we utilize our logos (praxeis meta logou). By using our logos, the end of human beings is happiness. !is shows us that the end (telos) of a human and the activity (energeia) work together. It seems that our happiness does not have to do with the divine being. However, Aristotle thinks that this happiness ultimately occurs with the divine being: If happiness is an activity in accord with virtue, it is reasonable that it would accord with the most excellent virtue, and this would be the virtue belonging to what is best. So whether this is the intellect or something else that seems naturally to rule, to command, and to possess intelligence concerning what is noble and divine, whether it itself is in fact divine or the most divine of the things in us—the activity of this, in accord with the virtue proper to it, would be complete happiness. And that this activity is contemplative has been said. (1177a13-18, Nicomachean Ethics) Our happiness ultimately belongs to the divine being. !is is complete happiness. !is is contemplation. We think and contemplate. !is is our activity (energeia). We want happiness. !is is our goal (telos). !is happiness is contemplation. !erefore, a human being is for contemplating. Both thinking and contemplating–our activity (energeia)–are possible because of our logos. Both thought and contemplation–(telos)–occur with the divine being.20 Since the genus of a human is animal, if we accept Aristotelian teleological view, we can accurately de"ne a human as a thinking—or rational— animal.21 Aristotle at various times refers to human as a rational animal, at other times as a featherless two-footed animal. We have seen two distinct de"nitions of a human that appear throughout Aristotle’s corpus. !ey are not just two interchangeable de"nitions with equal utility. One is taxonomic, an example of what de"nition is 20 Metaphysics 1026a15-18, 1026a28-31 21 One might point out that if we de"ne a human as a political animal, it is also arbitrary. Sometimes, we de"ne a human as a political animal. At other times, we de"ne a human as a rational animal. It is a reasonable argument. However, it seems that for Aristotle, political activity is subordinate to rational activity. A human being takes pleasure in society and lives an ethical life because of reason. !en, one might ask again how a political life and a contemplative life can be described under the realm of the de"nition of a human: “A human is a rational animal.” A politician is a practitioner who pursues practical wisdom. A philosopher, by contrast, pursues speculative wisdom. Insofar as both a politician and a philosopher seek wisdom with reason, both of them are rational. 41Issue X ◆ Spring 2023 How Can We Reach the True Definition of Something like. !e other one represents the achievement that can be made when we know the true end of a thing—that is, true de"nition. Now it gives us a model to follow in other cases and an appreciation for the di)culty of reaching de"nition in cases where the telos is hidden from us. CONCLUSION For Aristotle, the question “What is being?” is signi"cant. !is question is the same as the question “What is a substance?” !is question leads us to what the essence is. Since the de"nition and the essence are one in some sense, if we know the essence of something, we can reach its de"nition. However, without knowing the ultimate di#erentia of something, it is unlikely for us to reach its true de"nition. For artifacts, we have access to the true purpose of anything that we make as humans. In addition, we are for thinking.22 So, we can reach the true de"nitions of artifacts and ourselves. However, for natural things other than humans, it is unclear whether we can know their purposes or not. We do not know whether our interpretation of phenomena is the same as the true end of a thing. While we experience the world, we observe the phenomena of things. We see an acorn growing up and becoming an oak tree. We think the "nal cause of an acorn is to become an oak tree. Even if Aristotle says that our perception of proper objects is always true,23 does Aristotle think that we can know the ends of all the natural things? For instance, what is the unique end of the mature oak tree? It is di)cult to answer. All things are ordered and related to each other, contributing to the good of the world. !ey contribute to the order, the beauty, and the good of the world in their own ways. 24 !erefore, unless we know the order of the world, it is unlikely that we know the true end of things. Hence, for natural things, taxonomic de"nitions might have to be enough. If we know their true ends, we will be happy. However, we may or may not know their purposes. So, we may know only what the de"nition is like. A horse, for instance, is approximately a four-legged hoofed animal, but this de"nition misses its essence. However, this does not mean that Aristotle’s investigation of being and pursuit of wisdom in Metaphysics has failed. !e mere taxonomic de"nition can be useful for scientists as Aristotle was a scientist who tried to understand the physical world scienti"cally. Furthermore, if the goal of humans is thinking and contemplating using our logos, then his task cannot be considered a failure. !inking and knowing are not the same. We are not sure whether we can know, but we can continue to seek wisdom about, for each thing that exists, the end. 22 !ere is a possibility that Aristotle might think that not every human being is for thinking. For example, while natural slaves are humans, are they indeed for thinking? In addition, poets compose not by using reason but by inspiration. !is problem led us to the question of whether we can even de"ne a human. However, this is a wholly di#erent matter. Although signi"cant, we will follow Aristotle’s account of the goal of a human in Metaphysics and Ethics in this essay. 23 De Anima 427b13 24 Metaphysics 1075a15-25 42 Dianoia: The Undergraduate Philosophy Journal of Boston College REFERENCES Aristotle, Metaphysics. Loeb Classic Library edition. Trans. Hugh Tredennick. Cambridge, Massachusetts: Harvard University Press, 1933. Aristotle, Metaphysics. Trans. C.D.C. Reeve. Hackett Publishing Company, Inc, 2016. Aristotle, On the Soul. Loeb Classic Library edition. Trans. W.S. Hett. Harvard University Press, 1936. Aristotle, Categories. Trans. J. L. Ackrill. Oxford: Clarendon Press, 1963. Aristotle, Parts of Animals. Trans. William Ogle. New York: Garland Publishing, 1987 Aristotle, Physics. Trans. Robin Water"eld. New York: Oxford University Press, 1996. Aristotle, Politics. Trans. Carnes Lord. !e University of Chicago Press, 2013. Aristotle, Nicomachean Ethics. Trans. Robert C. Bartlett and Susan D. Collins. Chicago and London: !e University of Chicago Press, 2011.