| 12355 | 'Plane' is the genus of plane figures, and 'solid' of solids, with differentiae picking out types of corner [Aristotle] |
| Full Idea: 'Plane' is the genus of figures in the plane, and 'solid' is the genus of solids. For every figure is either a plane with abc features or a solid with xyz features, so it is the plane and solid which underlie these differentiae. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1024b01) | |
| A reaction: Thus you could hardly define a square by merely mentioning that it is a 'plane figure', and you would need pretty precise differentiae before you could be certain you were only dealing with a square, and not a parallelogram. |
| 12352 | Whiteness can only belong to man because an individual like Callias happens to be white [Aristotle] |
| Full Idea: If Callias is a white man, then whiteness belongs in a way to Callias, or to man, in as much as Callias, to whom it is accidental here to be a man, is white. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1030b20) | |
| A reaction: The point here is that 'white' can only belong to 'man' because some individual man happens to be white. |
| 11383 | A definition is of the universal and of the kind [Aristotle] |
| Full Idea: A definition is of the universal [tou katholou] and the form [tou eidous, kind, species]. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1036a28) | |
| A reaction: [Alternative translations by Vasilis Politis] Since the essence of a thing is a particular (Idea 11382), this seems to mean that the definition is NOT giving the essence, contrary to the account of Kit Fine. I take the essence to be explanatory. |
| 10961 | Definition by division is into genus and differentiae [Aristotle] |
| Full Idea: The contents of definition by division are the so-called primary genus (such as 'animal') and the differentiae. ...It should always be prosecuted until the level of non-differentiation is reached, ...and the last differentia will be the substance. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1037b30) | |
| A reaction: [Second half at 1038a14] Note that this is only one type of Aristotelian definition, the 'definition by division'. The aim of this type of definition is to analyse down to substance. Presumably you can't ignore crucial features found on the way? |
| 12356 | If the genus is just its constitutive forms (or matter), then the definition is the account of the differentiae [Aristotle] |
| Full Idea: If the genus simpliciter does not exist over and above the specific forms constitutive of it, alternatively if it exists just as matter, it is evident what the definition is, the account derived just from the differentiae. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1038a05-) | |
| A reaction: This is how I understand an Aristotelian definition - as a lengthy and fine-grained account of the details which pick out some individual within the main genus which constitutes it. |
| 17040 | If I define you, I have to use terms which are all true of other things too [Aristotle] |
| Full Idea: Suppose I was trying to define you. I would say you are an animal that is lean or white or some such, all of which also apply to other things. | |
| From: Aristotle (Metaphysics [c.324 BCE], 1040a13) | |
| A reaction: Commentators have taken this to mean that Aristotle is only interested in kinds and not individuals, but recent thinking says this is wrong. Universals prevent you from really getting at the thing you want to define. Definitions are limited. |
| 12081 | Aristotle's definitions are not unique, but apply to a range of individuals [Aristotle, by Witt] |
| Full Idea: I take Aristotle to be arguing that no definition applies uniquely to an individual - it is always potentially applicable to a range of individuals. | |
| From: report of Aristotle (Metaphysics [c.324 BCE], defs) by Charlotte Witt - Substance and Essence in Aristotle 4.2 n7 | |
| A reaction: So much the worse for Aristotle, I think. Surely unique entities can be defined? No one thinks their pet dog is just any dog, even after the age and breed have been identified. |
| 12353 | Species and genera are largely irrelevant in 'Metaphysics' [Aristotle, by Wedin] |
| Full Idea: Species and genera are largely irrelevant to the program of 'Metaphysics'. | |
| From: report of Aristotle (Metaphysics [c.324 BCE], kind) by Michael V. Wedin - Aristotle's Theory of Substance III.10 | |
| A reaction: The idea seems to be that Aristotle is seeking tools for getting at the primary being of a thing, and the notion of 'form' strikes him as a better account, because it explains the genera and species, rather than just naming them. |
| 12261 | Differentia are generic, and belong with genus [Aristotle] |
| Full Idea: The differentia, being generic in character, should be ranged with the genus. | |
| From: Aristotle (Topics [c.331 BCE], 101b18) | |
| A reaction: This does not mean that naming the differentia amounts to mere classification. I presume we can only state individual differences by using a language which is crammed full of universals. |
| 12263 | 'Genus' is part of the essence shared among several things [Aristotle] |
| Full Idea: A 'genus' is that which is predicated in the category of essence of several things which differ in kind. | |
| From: Aristotle (Topics [c.331 BCE], 102a32) | |
| A reaction: Hence a genus is likely to be expressed by a universal, a one-over-many. A particular will be a highly individual collection of various genera, but what ensures the uniqueness of each thing, if they are indiscernible? |
| 12272 | We describe the essence of a particular thing by means of its differentiae [Aristotle] |
| Full Idea: We usually isolate the appropriate description of the essence of a particular thing by means of the differentiae which are peculiar to it. | |
| From: Aristotle (Topics [c.331 BCE], 108b05) | |
| A reaction: I take this to be important for showing the definition is more than mere categorisation. A good definition homes in the particular, by gradually narrowing down the differentiae. |
| 12279 | The differentia indicate the qualities, but not the essence [Aristotle] |
| Full Idea: No differentia indicates the essence [ti estin], but rather some quality, such as 'pedestrian' or 'biped'. | |
| From: Aristotle (Topics [c.331 BCE], 122b17) | |
| A reaction: We must disentangle this, since essence is what is definable, and definition seems to give us the essence, and yet it appears that definition only requires genus and differentia. Differentiae seem to be both generic and fine-grained. See Idea 12280! |
| 12283 | In definitions the first term to be assigned ought to be the genus [Aristotle] |
| Full Idea: In definitions the first term to be assigned ought to be the genus. | |
| From: Aristotle (Topics [c.331 BCE], 132a12) | |
| A reaction: We mustn't be deluded into thinking that nothing else is required. I take the increasing refinement of differentiae to be where the real action is. The genus gives you 70% of the explanation. |
| 12289 | The genera and the differentiae are part of the essence [Aristotle] |
| Full Idea: The genera and the differentiae are predicated in the category of essence. | |
| From: Aristotle (Topics [c.331 BCE], 153a19) | |
| A reaction: The definition is words, and the essence is real, so our best definition might not fully attain to the essence. Aristotle has us reaching out to the world through our definitions. |
| 4385 | Aristotelian definition involves first stating the genus, then the differentia of the thing [Aristotle, by Urmson] |
| Full Idea: For Aristotle, to give a definition one must first state the genus and then the differentia of the kind of thing to be defined. | |
| From: report of Aristotle (works [c.330 BCE]) by J.O. Urmson - Aristotle's Doctrine of the Mean p.157 | |
| A reaction: Presumably a modern definition would just be a list of properties, but Aristotle seeks the substance. How does he define a genus? - by placing it in a further genus? |
| 13070 | If definitions must be general, and general terms can't individuate, then Socrates can't be defined [Aquinas, by Cover/O'Leary-Hawthorne] |
| Full Idea: Socrates has no definition if definitions by their nature must be in purely general terms, and if no purely general terms can succeed in uniquely singling out this signated matter. | |
| From: report of Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], 23) by Cover,J/O'Leary-Hawthorne,J - Substance and Individuation in Leibniz 1.1.2 | |
| A reaction: There seem to be two models. That general terms actually individuate the matter of Socrates, or that they cross-reference to (so to speak) define Socrates 'by elimination', as the only individual that fits. But the latter is a poor definition. |
| 11197 | The definitions expressing identity are used to sort things [Aquinas] |
| Full Idea: What sorts things into their proper genus and species are the definitions that express what they are. | |
| From: Thomas Aquinas (De Ente et Essentia (Being and Essence) [1267], p.92) | |
| A reaction: This is straight from Aristotle, though Aristotle's view is a little more complex, I think. If the definitions 'express what they are', then definitions seem to specify the essence. |
| 17239 | Definition is resolution of names into successive genera, and finally the difference [Hobbes] |
| Full Idea: The definition is nothing but a resolution of the name into its most universal parts; ...definitions of this kind always consist of genus and difference; the former names being all, till the last, general; and the last of all, difference. | |
| From: Thomas Hobbes (De Corpore (Elements, First Section) [1655], 1.6.14) | |
| A reaction: This is basically the scholastic Aristotelian view of definition. Note that Hobbes explicitly denies that the last step of the definition is general in character. |
| 12538 | Genus is a partial conception of species, and species a partial idea of individuals [Locke] |
| Full Idea: In this whole business of genera and species, the genus, or more comprehensive, but a partial conception of what is in the species, and the species but a partial idea of what is to be found in each individual. | |
| From: John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 3.06.32) | |
| A reaction: This is my feeling on the subject, that any definition that stops short of the individual, whence all categorisation flows, is inadequate. |
| 12980 | Genus and differentia might be swapped, and 'rational animal' become 'animable rational' [Leibniz] |
| Full Idea: The genus can very often be turned into the differentia, ...so that in place of saying that man is a 'reasonable animal' we could, if language permitted, say that man is an 'animable rational', a rational substance with animal nature. | |
| From: Gottfried Leibniz (New Essays on Human Understanding [1704], 3.03) | |
| A reaction: This is a very telling point which rather undermines any dogmatic approach to what Aristotle says about these sorts of definitions. I don't find this account of definitions very helpful anyway. Leibniz links it to the order of cataloguing. |
| 14266 | Aristotle sees hierarchies in definitions using genus and differentia (as we see them in sets) [Fine,K] |
| Full Idea: For us, sets constitute the most natural example of a hierarchical structure within the abstract realm. But for Aristotle it would have been definitions, via their natural division into genus and differentia. | |
| From: Kit Fine (Aristotle on Matter [1992], 1 n4) | |
| A reaction: Genus and differentia are only part of the story in Aristotle, and this remarks strikes me as perceptive. It is precisely the mapping of the explanatory hierarchy which Aristotle seeks in a good definition. |
| 12242 | Definition distinguishes one kind from another, and individuation picks out members of the kind [Oderberg] |
| Full Idea: To define something just means to set forth its limits in such a way that one can distinguish it from all other things of a different kind. To distinguish it from all other things of the same kind belongs to the theory of 'individuation'. | |
| From: David S. Oderberg (Real Essentialism [2007], 1.4) | |
| A reaction: I take Aristotle to have included individuation as part of his understanding of definition. Are tigers a kind, or are fierce tigers a kind, and is my tiger one-of-a-kind? |
| 12249 | 'Animal' is a genus and 'rational' is a specific difference [Oderberg] |
| Full Idea: The standard classification holds that 'animal' is a genus and 'rational' is a specific difference. | |
| From: David S. Oderberg (Real Essentialism [2007], 3.5) | |
| A reaction: My understanding of 'difference' would take it down to the level of the individual, so the question is - which did Aristotle believe in. Not all commentators agree with Oderberg, and Wedin thinks the individual substance is paramount. |