Authors/Thomas Aquinas/physics/L5/lect6

Lecture 6 Generic, specific, and numerical unity of motion

Latin	English
	Lecture 6 Generic, specific, and numerical unity of motion
lib. 5 l. 6 n. 1 Postquam philosophus posuit quasdam definitiones necessarias ad sequentia, procedit ad tractandum de unitate et diversitate motus. Et primo determinat de unitate et diversitate motus; secundo de contrarietate, quae est quaedam diversitatis species, ibi: amplius autem determinandum et cetera. Circa primum duo facit: primo distinguit unitatem motus secundum tres communes modos; secundo alterum eorum subdividit, ibi: quoniam autem continuus est et cetera. Circa primum tria facit: primo ostendit quomodo motus dicatur unus genere; secundo quomodo dicatur unus specie, ibi: specie autem unus est etc.; tertio quomodo dicatur unus numero, ibi: simpliciter autem unus et cetera.	695. After positing some definitions to be used later, the Philosopher now proceeds to discuss unity of motion and contrariety of motions. First he treats of the unity and diversity of motion; Secondly, of its contrariety, which is a kind of diversity, L.8, About the first he does three things: First he shows how motion is said to be generically one; Secondly, how it is specifically one, at 697; Thirdly, how it is numerically one, at 699.
lib. 5 l. 6 n. 2 Dicit ergo primo quod motus dicitur unus multipliciter, secundum quod et ipsum unum in communi acceptum multipliciter dicitur, scilicet genere et specie et numero. Dicitur autem motus unus genere, secundum figuras praedicamenti. Omnes enim qui sunt in una coordinatione praedicamenti, possunt dici unus motus genere: sicut omnis loci mutatio est unus motus genere, quia est in uno praedicamento ubi; differt autem genere ab alteratione, quae est in praedicamento qualitatis, ut supra dictum est.	696. He says therefore (515 227 b3) that there are a number of ways in which a motion is one, just as one itself has many senses: i.e., generically, specifically and numerically. A motion is said to be generically one according to the different predicaments. For all motions that are assigned to one and the same predicament can be called generically one; thus every local motion is one generic motion, because each is in the predicament where, and differs generically from alteration, which is in the predicament quality, as has been said above.
lib. 5 l. 6 n. 3 Deinde cum dicit: specie autem unus est etc., ostendit quomodo motus sit unus specie. Et primo ostendit propositum; secundo movet quandam dubitationem, ibi: dubitabit autem aliquis et cetera. Dicit ergo primo quod motus dicitur unus specie, cum non solum est unus secundum genus, sed etiam secundum speciem individuam, idest specialissimam, quae non dividitur in alias species. Sunt enim quaedam species quae dividuntur in alias species; sicut color species est qualitatis, sed tamen habet differentias, quibus in diversas species dividitur. Unde motus qui sunt secundum colores, possunt esse diversi specie, sicut dealbatio et denigratio: sed omnis dealbatio est eadem secundum speciem, et similiter omnis denigratio; quia albedini non sunt amplius species, in quas dividatur. Sed tamen si sunt quaedam quae sunt simul genera et species, manifestum est quod motus qui conveniunt in specie subalterna, sunt ut unum specie, idest secundum quid unus; sed simpliciter non sunt unus specie. Sicut scientia est quaedam species existimationis, et genus diversarum scientiarum: unde omnis doctrinatio, quae est motus ad scientiam, est quodammodo una specie, non tamen simpliciter; quia doctrinatio qua docetur grammatica, est simpliciter alia specie ab ea qua docetur geometria. Attendendum est autem, quod in praemissis unitatem et diversitatem motus determinavit secundum genera et species in quibus contingit motum esse, quia motus quodammodo reducitur ad genus rerum in quibus est motus.	697. Then at (516 227 b6) he shows how motions are specifically one. First he shows this; Secondly, he raises a question, at 698. He says therefore first (516 227 b6) that a motion is called specifically one when, besides being a generic one, it also takes place in a species incapable of subdivision. For some species can be subdivided into other species, as color, which is a species of quality, is capable of differences that make for sub-species. Hence motions in regard to color can be diverse in species, as whitening and blackening; but all cases of whitening are specifically the same (just as all cases of blackening are), for there are no sub-species of whitening. But when it happens that the species is at the same time a genus, then the motions found in a subalternate species are qualifiedly one, although, strictly speaking, they are not of the same species. Thus science is a species of knowledge, as well as a genus of the various types of science. Hence all indoctrination, which is a movement toward science, is in some sense specifically the same, although, strictly speaking, it is not, for the indoctrination by which grammar is taught is absolutely different in species from that by which geometry is taught. Now it should be observed that in the foregoing the Philosopher has based the unity and diversity of motion on the genera and species in which motion can occur, because motion is in a certain way reduced to the genus in which the motion is.
lib. 5 l. 6 n. 4 Deinde cum dicit: dubitabit autem aliquis etc., movet quandam dubitationem circa praemissa: utrum scilicet ex necessitate sit unus specie motus, cum aliquid idem mutatur multoties de eodem in idem; sicut si unum punctum secundum geometras, qui imaginantur punctum moveri, moveatur ex hoc loco in hunc locum multoties. Et hoc quidem videtur secundum praemissa. Si enim motus qui in eandem speciem sunt, ut in albedinem, sunt idem specie, multo magis duo motus qui sunt in eundem locum numero. Si autem hoc concedatur, sequitur inconveniens, scilicet quod motus rectus sit unus specie motui circulari. Contingit enim ab hoc loco in hunc locum primo quidem moveri circulariter, quasi per arcum quendam; postmodum vero motu recto, quasi per lineam rectam. Et similiter sequitur in motibus animalium, quod ambulatio, quae est per lineam rectam, sit eadem secundum speciem volutationi, qua animal per lineam circularem volvendo se movetur. Hanc autem dubitationem solvit secundum praemissa. Determinatum est enim quod, si id in quo est motus, est alterum specie, et motus est alter specie; ut sic ad hoc quod motus sit idem specie, non solum requiratur identitas termini secundum speciem, sed etiam identitas eius per quod transit motus. Manifestum est autem quod linea recta et circularis sunt diversae secundum speciem: unde motus circularis et rectus, et volutatio et ambulatio, non sunt idem secundum speciem, quamvis sint inter eosdem terminos; quia via non est eadem secundum speciem. Sed si sint idem termini, et eadem via secundum speciem, sunt idem motus secundum speciem. Et multo magis si termini et via sunt eadem numero, motus iterati erunt idem secundum speciem.	698. Then at (517 227 b14) he raises a question about the foregoing: Whether a motion is specifically one and the same when the same thing changes frequently from the same to the same, e.g., when a point (according to the geometers who imagine that a point can be moved) changes again and again from this place to that. Now according to the foregoing it seems that the answer should be Yes. For if all motions that tend to the same species, e.g., whiteness, are specifically the same, a fortiori two motions from the same origin to the same terminus should be specifically one. But if that were so, then it would follow that a rectilinear motion is specifically the same as a circular motion. For it is possible to pass from this place to that by means of a circular motion, i.e., by describing an arc, and after by going in a straight line. Likewise, it would follow that in the motions of animals, walking (which is in a straight line) would be specifically the same as whirling, which consists in turning oneself in circles. However, he answers this difficulty in the light of the foregoing. For it has been decided that if that in which the motion takes place is specifically different (as in the present instance the circular path is specifically different from the straight), the motion itself is also different. Consequently, in order that two motions be specifically the same, not only must the goal be specifically the same but also that through which the motion passes. Now it is clear that a straight line is specifically different from the curved. Consequently, a circular and a rectilinear motion, as well as walking and whirling, are not specifically the same, even though they tend to the same goal, because the paths are not specifically the same. But if the goals are identical and the paths specifically the same, then the motions are specifically the same; and much more so, if the goals and the path are numerically the same, the same repeated motions will be specifically the same.
lib. 5 l. 6 n. 5 Deinde cum dicit: simpliciter autem unus motus est etc., ponit tertium modum, quo motus dicitur unus numero. Et circa hoc duo facit: primo manifestat quis motus sit unus numero; secundo circa hoc movet quasdam dubitationes, ibi: Socratem autem et cetera. Dicit ergo primo quod secundum praedictos modos non dicitur motus unus simpliciter, sed secundum quid, scilicet genere et specie. Tertio autem modo dicitur motus simpliciter unus, qui est unus numero secundum suam essentiam. Quis autem motus sit hoc modo unus, manifestum erit distinguendo ea quae requiruntur ad motum. Sunt enim numero tria circa quae consistit unitas motus: scilicet subiectum quod movetur; et genus vel species, in qua est motus; et tempus quando movetur. Et manifestat singula. Quod movetur quidem dictum est, quia necesse est aliquid esse in quocumque motu quod movetur, sicut hominem aut aurum vel quodcumque corpus. Et similiter necesse est hoc, vel quaecumque alia mobilia, moveri in aliquo genere vel specie, puta in loco aut in passione, idest in passibili qualitate. Et similiter necesse est considerare quando movetur: quia omne quod movetur, movetur in tempore. Contingit autem de numero horum trium inveniri unum genere aut specie in re in qua est motus, sicut in loco vel in qualitate. Sed in tempore non est attendenda quantum ad unitatem motus unitas generis vel speciei, cum non sit nisi unum tempus secundum speciem; sed quod sit habitum, idest continuo consequens absque interpolatione. Unitas autem motus secundum quam dicitur simpliciter unus, consistit in unitate omnium horum. Oportet enim id in quo est motus, esse unum et indivisibile, eo modo quo species specialissima indivisibilis dicitur. Et iterum oportet ipsum tempus, quando fit motus, esse unum continuum et non deficiens, idest absque interpolatione. Et tertio oportet id quod movetur esse unum. Sed excludit duos modos unitatis subiecti, qui non sufficiunt ad hoc, quod motus sit unus simpliciter. Primus modus est secundum accidens; sicut Coriscus et albus sunt unum secundum accidens, nec tamen motus proprius Corisci, et motus proprius albi est unus. Motus enim proprius albi est nigrum fieri, et motus proprius Corisci est ambulare; qui quidem motus differunt. Secundus modus est unitas generis vel speciei: non enim ad hoc quod sit unus motus numero, sufficit quod subiectum sit unum sicut aliquid commune, vel genus vel species. Contingit enim duos homines in eodem tempore sanari, et secundum eandem speciem sanationis, puta quia sanantur de ophthalmia, quae est infirmitas oculorum: et sic concurrit unitas ipsius quando, et eius in quo, et unitas subiecti secundum speciem. Non tamen hae duae sanationes sunt unus motus numero, sed unus specie.	699. Then at (518 227 b21) he posits the third way in which a motion is said to be one; namely, numerically. About this he does two things: First he explains when a motion is numerically one; Secondly, he raises some question on this point, at 700. He says therefore first at (516 227 b6) that in the first two senses motions are not unqualifiedly one, but they are one only in a sense, i.e., in genus and species. But in the third sense a motion is unqualifiedly one, i.e., when it is numerically one in its essence. Which motion is one in this way will be clear, if we distinguish the things required for motion: for numerically there are three things on which the unity of a motion depends: first, the subject which is being moved; secondly, the genus or species of the motion; thirdly, the time in which the motion takes place. And he explains each of these individually. A subject of motion is required, because in every case of motion there must be something that is being moved, as a man or gold or some body. Likewise the subject must be affected by some genus or species of motion, such as place or a passible quality. Again, the time must be considered, because whatever is moved is moved in time. Now among these three things, the generic or specific unity of the motion can depend on the thing in which there is motion; for example, on the place or quality. But the time does not account for the generic or specific unity of the motion, for there is only one specific time; rather it accounts for the continuity of the motion, i.e., that it flows on without interruption. But unity of motion, in the sense of unqualified unity, depends on all three. For that in which the motion exists must be one and indivisible in the way that a species incapable of further subdivision is said to be one. Further, the time during which the motion occurs must be continuous without any breaks. Thirdly, the subject in motion must be one. However, there are two types of unity of subject which are not sufficient to guarantee that the motion is unqualifiedly one. The first type is accidental: for example, Coriscus and white are accidentally one, but the motion proper to Coriscus in not the same as the motion proper to white. For the proper motion of white is to become black and the motion proper to Corisicus is to walk; and these are different. The second type is generic and specific unity. For in order that a motion be numerically one, it is not enough that the subject be one as something common either generically or specifically. For it is possible that two men are being healed during the same period of time in regard to the same thing; for example, from inflammation of the eye, so that the time is one and the species of motion is one, and the subject is one in species. Yet these two healings are not one numerically but only specifically.
lib. 5 l. 6 n. 6 Deinde cum dicit: Socratem autem etc., introducit quandam dubitationem. Et circa hoc tria facit: primo ponit id quod videtur in primo aspectu de unitate motus secundum numerum; secundo movet dubitationem circa hoc, ibi: habet autem dubitationem etc.; tertio determinat veritatem, ibi: eadem enim ratio est et cetera. Dicit ergo primo quod contingit aliquod unum mobile, ut Socratem, secundum alterationem eandem specie, alterari in uno tempore, et iterum in alio; sicut si sanetur bis de ophthalmia. Haec autem iterata alteratio erit unus motus numero, ut videtur in primo aspectu, si sanitas quae acquiritur sit eadem numero. Et hoc erit si contingat id quod est corruptum, iterum fieri unum numero, quod videtur impossibile. Sanitas enim quae in prima alteratione fuit acquisita, postmodum fuit corrupta; et non potest recuperari eadem numero. Sed videtur quod si recuperetur eadem numero, quod alteratio sequens esset unus numero motus cum prima: si vero non recuperetur eadem sanitas numero, erit quidem motus idem specie, sed non unus numero.	700. Then at (519 228 a3) he raises a question. And about this he does three things: First he mentions what at first glance seems to be a motion numerically one; Secondly, he raises a question about this, at 701; Thirdly, he gives the true solution, at 702. He says therefore first (519 228 a3) that it is possible for one mobile, e.g., Socrates, to be altered at two different times with respect to the same specific disease, for example, if he is twice healed of eye-inflammation. This repeated healing will at first sight be numerically one motion, if the health acquired is numerically the same in both cases. And this will be so, if it is possible for that which ceased to be to come again into being as the same numerical thing—which seems impossible. For the health acquired after the first alteration was later lost and the same numerical health cannot be regained. But it seems that if the same numerical health were regained, the second alteration would be numerically the same motion as the first; whereas if the same numerical health is not regained, the motion will not be numerically the same but specifically.
lib. 5 l. 6 n. 7 Deinde cum dicit: habet autem dubitationem etc., movet quandam aliam dubitationem circa hoc. Et dubitatio talis est: si aliquis continue perseveret in sanitate, vel in quocumque alio accidente, utrum una sanitas, vel quicumque alius habitus aut passio, possit esse in corporibus? Et videtur quod non; quia quibusdam philosophis visum fuit, quod omnia subiecta quae habent aliquas qualitates aut habitus, sint in continuo motu et fluxu. Si ergo in aliquo qui sanus perseverat, una et eadem sanitas est, quae fuit in mane et quae est nunc in meridie vel sero; non videtur posse reddi ratio quare, etiam si aliquis deficit a sanitate et iterum accipiat sanitatem, secunda sanitas recuperata non sit una numero cum sanitate prius habita. Hanc autem dubitationem Aristoteles non solvit, quia non est ad propositum; sed magis ad considerationem metaphysici pertinet, ad quem pertinet considerare communiter de uno et multo, et eodem et diverso. Et iterum quia illa dubitatio super falso fundatur, scilicet quod omnia sint in continuo motu et fluxu, quod Heraclitus opinatus est, et Aristoteles improbat in IV Metaphys. Nec tamen est similis ratio: quia quamdiu sanitas manet, licet varietur homo secundum sanitatem, ut puta si fiat homo magis vel minus sanus, non intercipitur esse sanitatis, sicut intercipitur quando totaliter corrumpitur sanitas.	701. Then at (520 228 a6) he raises another difficulty on this point. It is this: if someone continually perseveres in health or any other accident, could the health, or any other habit or passion in bodies, be one? It seems not, because certain philosophers believe that all subjects that possess certain qualities or habits are in continuous motion and flux. If, therefore, in the case of a person who remains healthy, there is one and the same health at dawn and at noon and in the evening, there seems to be no reason why in the case of a person who gets sick and then recovers, the health recovered is not numerically the same as the one previously possessed. Aristotle does not settle this question: first, because it is not ad rem, since it pertains to metaphysics, whose province is to consider the one and the many, the same and the diverse; and, secondly, because this difficulty is based on the false assumption that all things are in a state of continuous change and flux, as Heraclitus believed—an opinion which Aristotle refutes in IV Metaphysics. Moreover, the two cases are not the same: for as long as health remains in spite of fluctuations in degree, the original health is not interrupted, as it is in the case of one who completely loses his health.
lib. 5 l. 6 n. 8 Deinde cum dicit: eadem enim ratio etc., determinat veritatem circa id quod praedixerat. Dixerat enim supra, quod si sit eadem qualitas quae recuperatur, erit idem motus numero secunda alteratio cum prima; si vero non redit eadem numero qualitas, sequitur quod non sit unus actus numero. Et interposita quadam dubitatione, quasi assignans rationem praemissorum, subdit quod ideo praemissa dicta sunt, quia eadem ratio videtur in primo aspectu de unitate qualitatis et motus. Sed intantum differunt, quia bene sequitur, si duo motus sint idem eo modo sicut aliquis motus dicitur unus numero, necesse est quod habitus, id est qualitas acquisita per motum, sit una: quia unus numero actus est unius numero qualitatis acquisitae per actum illum. Sed si qualitas sit una quae redit, potest alicui videri quod non propter hoc sit unus actus: non enim, si terminus motus est unus numero, oportet quod motus sit unus numero. Quod patet in motu locali. Cum enim ambulans pausat, cessat illa ambulatio: sed quando iterum ambulare incipit, iterum ambulatio erit. Si ergo dicatur quod sit una et eadem ambulatio, contingit quod unum et idem sit et corrumpatur multoties; quod est impossibile. Sic igitur et si contingeret quod eadem numero sanitas reparetur, non sequeretur quod secunda sanatio esset idem numero motus cum prima; sicut nec secunda ambulatio cum prima, quamvis utraque sit ad eundem locum numero. Ulterius concludit quod istae dubitationes sunt extra principalem intentionem, et ideo sunt praetermittendae.	702. Then at (521 228 a12) he determines the truth in regard to the case mentioned in 700. For he mentioned there that if it is the same quality that is recovered, the second alteration will be numerically the same motion as the first; if the same numerical quality is not recovered, then it is not numerically the same act. Having presented a certain difficulty as though giving a reason for what was set down above, he adds that the reason for raising the difficulty was that at first sight it seemed that the same argument would hold good for the unity of quality and of motion. But there is a difference: for it does follow that if two motions are the same in the manner in which a motion is said to be numerically one, then the habit, i.e., the quality, acquired by the motion is one; because numerically the same quality is produced by an act numerically one. However, if the quality that returns is one, not everyone would agree that the act is one; for if the terminus of two motions is numerically one, it does not mean that the motions were numerically one. This is evident in local motion. For when a person interrupts his walk, the act of walking ceases; but when he resumes, the act resumes. Now, if you were to say that the whole journey is one act of walking that ceases to be and is then revived, then it would follow that one and the same thing can exist and cease to exist any number of times—which is impossible. In like manner if the same numerical health is again and again recovered, it does not follow that the second healing was the same motion as the first, any more than a second walk is the same as a first, even though both go toward the same numerical goal. Finally, he concludes that these difficulties lie outside the present enquiry and are for that reason to be passed over.