Authors/Thomas Aquinas/physics/L1/lect2

LECTURE 2 THE OPINIONS OF THE ANCIENT PHILOSOPHERS ABOUT THE PRINCIPLES OF NATURE

Latin	English
	LECTURE 2 (184 b 15-185 a 19) THE OPINIONS OF THE ANCIENT PHILOSOPHERS ABOUT THE PRINCIPLES OF NATURE AND OF BEINGS. IT DOES NOT PERTAIN TO NATURAL SCIENCE TO DISPROVE SOME OF THESE OPINIONS
lib. 1 l. 2 n. 1 Posito prooemio, in quo ostensum est quod scientia naturalis debet incipere a principiis universalioribus, hic secundum praedictum ordinem incipit prosequi ea quae pertinent ad scientiam naturalem. Et dividitur in duas partes: in quarum prima determinat de principiis universalibus scientiae naturalis; in secunda determinat de ente mobili in communi, de quo intendit in hoc libro; et hoc in tertio libro, ibi: quoniam autem natura est et cetera. Prima in duas: in prima determinat de principiis subiecti huius scientiae, idest de principiis entis mobilis inquantum huiusmodi; in secunda de principiis doctrinae, in secundo libro, ibi: eorum quae sunt et cetera. Prima autem in duas: in prima prosequitur opiniones aliorum de principiis communibus entis mobilis; in secunda inquirit veritatem de eis, ibi: omnes igitur contraria principia et cetera. Circa primum tria facit: primo ponit diversas opiniones antiquorum philosophorum de principiis communibus naturae; secundo ostendit quod aliquas earum prosequi non pertinet ad naturalem, ibi: id quidem igitur etc.; tertio prosequitur opiniones improbando earum falsitatem, ibi: principium autem et cetera. Circa primum duo facit: primo ponit diversas opiniones philosophorum de principiis naturae; secundo ostendit eandem diversitatem esse circa opiniones philosophorum de entibus, ibi: similiter autem quaerunt et cetera.	12. Having completed the preface in which it was shown that natural science ought to begin with the more universal principles, here, according to the order already stated, he begins to pursue those matters which pertain to natural science. This discussion is divided into two parts. In the first part he treats the universal principles of natural science. In the second part he treats mobile being in common (which is what he intends to treat in this book).’ This is taken up in Book III, where he says, ‘Nature has been defined ...’ (200 b 12; L1). The first part is divided into two parts. First he treats the principles of the subject of this science, that is, the principles of mobile being as such. Secondly he treats the principles of the doctrine. This he does in Book II, where he says, ‘Of things that exist...’ (192 b 8; L1). The first part is divided into two parts. First he considers the opinions others have had concerning the common principles of mobile being. Secondly he seeks the truth concerning them, where he says, ‘All thinkers, then, agree ...’ (188 a 19; L10). Concerning the first part he makes three points. First he sets forth the different opinions of the ancient philosophers concerning the common principles of nature. Secondly, where he says, ‘Now to investigate ...’ (184 b 25 #15), he shows that it does not pertain to natural science to pursue some of these opinions. Thirdly, where he says, ‘The most pertinent question...’ (185 a 20; L3), he considers these opinions, showing their falsity. Concerning the first part he makes two points. First he sets forth the different opinions of the philosophers concerning the principles of nature. Secondly, where he says, ‘A similar inquiry is made ...’ (184 b 23 #14), he shows that this same diversity exists with reference to the opinions of the philosophers concerning beings.
lib. 1 l. 2 n. 2 Dicit ergo primo quod necesse est esse unum principium naturae aut multa; et utraque pars habuit philosophos opinantes. Quidam enim eorum posuerunt unum principium, quidam multa. Et eorum qui posuerunt unum, quidam posuerunt illud esse immobile, sicut Parmenides et Melissus, de quorum opinione infra patebit; quidam vero posuerunt illud esse mobile, scilicet antiqui naturales. Quorum quidam posuerunt aerem esse principium omnium naturalium, ut Diogenes; quidam vero aquam, ut Thales; quidam vero ignem, ut Heraclitus; alii vero aliquid medium inter aerem et aquam, ut vaporem. Nullus vero eorum qui posuerunt principium unum tantum, dixit illud esse terram, propter eius grossitiem. Huiusmodi autem principia mobilia dicebant, quia per horum alicuius rarefactionem et condensationem alia fieri dicebant. Eorum vero qui posuerunt plura principia, quidam posuerunt ea finita, quidam posuerunt infinita. Eorum autem qui posuerunt ea esse finita, licet plura uno, quidam posuerunt ea esse duo, scilicet ignem et terram, ut infra dicet de Parmenide; quidam vero tria, scilicet ignem, aerem et aquam (nam terram quasi compositam existimabant propter eius grossitiem); alii vero posuerunt ea esse quatuor, scilicet Empedocles, vel etiam secundum aliquem alium numerum (quia et ipse Empedocles cum quatuor elementis posuit duo alia, scilicet amicitiam et litem). Qui vero posuerunt plura infinita, diversificati sunt. Democritus enim posuit indivisibilia corpora quae dicuntur atomi, esse principia omnium rerum. Sed huiusmodi corpora posuit esse omnia unius generis secundum naturam, sed tamen differebant secundum figuram et formam: et non solum differebant, sed contrarietatem ad invicem habebant. Ponebat enim tres contrarietates, unam secundum figuram, quae est inter curvum et rectum; aliam secundum ordinem, quae est prioris et posterioris; aliam secundum positionem, scilicet ante et retro, sursum et deorsum, dextrorsum et sinistrorsum. Et sic ex illis corporibus unius naturae existentibus, diversa fieri ponebat secundum diversitatem figurae, positionis et ordinis atomorum. Ex hac autem opinione dat intelligere oppositam opinionem, scilicet Anaxagorae, qui posuit infinita principia, sed non unius generis secundum naturam. Posuit enim principia naturae esse infinitas partes minimas carnis et ossis et aliorum huiusmodi, ut manifestum erit inferius. Attendendum autem quod non divisit plura principia per mobilia et immobilia, quia nullus ponens prima principia plura, potuit ponere ea immobilia: cum enim omnes ponerent contrarietatem in principiis, contraria autem nata sunt se alterare, cum pluralitate principiorum immobilitas stare non poterat.	13. He says, therefore, first of all, that it is necessary that there be one principle of nature or many. And each position has claimed the opinions of the philosophers. Some of them, indeed, held that there is one principle, others held that there are many. And of those who held that there is one principle, some held that it was immobile, as did Parmenides and Melissus, whose opinion he will examine below. Some, however, held that it was mobile, as did. the natural philosophers. Of these, some held that air was the principle of all natural things, as Diogenes; others that it was water, as Thales; others that it was fire, as Heraclitus; and still others some mean between air and water, such as vapour. But none of those who held that there was only one principle said that it was earth because of its density. For they held that principles of this sort were mobile, because they said that other things come to be through the rarefication and condensation of certain of these principles. Of those who held the principles to be many, some held them to be finite, others held that they were infinite. Of those who held that they were finite (although more than one) some held that there were two, i.e., fire and earth, as Parmenides will say below [L 10]. Others held that there were three, i.e., fire, air and water (for ‘they thought earth to be in some way composed because of its density). Others, however, held that there were four, as Empedocles did, or even some other number, because even Empedocles himself along with the four elements posited two other principles, namely, friendship and strife. Those who held that there was an infinite plurality of principles had a diversity of opinions. For Democritus held that indivisible bodies which are called atoms are the principles of all things. And he held that bodies of this sort were all of one genus according to nature, but that they differed according to figure and form, and that they not only differed but even had contrariety among themselves. For he held three contrarieties: one according to figure, which is between the curved and the straight, another according to order, which is the prior and the posterior, and another according to position, namely, before and behind, above and below, to the right and to the left. And so he held that from these bodies existing of one nature different things come to be according to the diversity of the figure, position and order of the atoms. In this opinion, then, he gives us some basis for understanding the opposing opinion, namely that of Anaxagoras who held that the principles were infinite, but not of one genus according to nature. For he held that the principles of nature were the infinite, smallest parts of flesh and bone and other such things, as will be made clear below. It must be noted, however, that he did not divide these many principles into mobile and immobile. For none of these who held that the first principles were many held that they were immobile. For since an place contrariety in the principles, and since it is natural for contraries to change, immobility could not stand with a plurality of principles.
lib. 1 l. 2 n. 3 Deinde cum dicit: similiter autem quaerunt etc., ostendit quod eadem diversitas opinionum est circa entia. Et dicit quod similiter physici, inquirentes de iis quae sunt, idest de entibus, quaerunt quot sint, utrum scilicet unum aut plura; et si sint multa, utrum sint finita vel infinita. Et ratio huius est, quia antiqui physici non cognoverunt nisi causam materialem, de aliis autem causis parum tetigerunt. Ponebant autem formas naturales esse accidentia, sicut et artificiales: sicut ergo tota substantia artificialium est eorum materia, ita sequebatur secundum eos quod tota substantia naturalium esset eorum materia. Unde qui ponebant tantum unum principium, puta aerem, putabant quod alia entia essent aer secundum suam substantiam: et simile est de aliis opinionibus. Et hoc est quod dicit, quod physici quaerunt ex quibus sunt quae sunt: idest, inquirendo de principiis inquirunt causas materiales, ex quibus entia esse dicuntur. Unde patet quod quando inquirunt de entibus, utrum sint unum aut plura, eorum inquisitio est de principiis materialibus, quae elementa dicuntur.	14. Secondly, at the point where he says, ‘A similar inquiry is made...’ (184 b 23; L9), he shows that there is the same diversity of opinions concerning beings. He says that in like manner the physicists, when inquiring about those things which are, i.e., about beings, wondered how many there are, i.e., whether there is one or many; and if many, whether finite or infinite. And the reason for this is that the ancient physicists did not know any cause but the material cause (although they touched lightly upon the other causes). Rather they held that the natural forms were accidents, as the forms of artificial things are. Since, therefore, the whole substance of artificial things is their matter, so it followed, according to them, that the whole substance of natural things would be their matter. Hence those who held one principle only, for example, air, thought that other beings were air according to their substance. And the same is true of the other opinions. Hence Aristotle says that the physicists seek what is in that from which things are, i.e., in inquiring about principles they sought the material causes from which beings are said to be. Whence it is clear that when they inquire about beings, whether they are one or many, their inquiry concerns the material principles which are called elements.
lib. 1 l. 2 n. 4 Deinde cum dicit: id quidem igitur etc., ostendit quod aliquam istarum opinionum improbare non pertinet ad naturalem. Et circa hoc duo facit: primo ostendit quod improbare opinionem Parmenidis et Melissi non pertinet ad scientiam naturalem; secundo assignat rationem quare ad praesens est utile eam improbare, ibi: sed quoniam de natura et cetera. Circa primum duo facit: primo ostendit quod non pertinet ad scientiam naturalem improbare praedictam opinionem; secundo quod non pertinet ad eam solvere rationes quae ad probandum ipsam inducuntur, ibi: aut solvere rationem et cetera. Primum ostendit duabus rationibus, quarum secunda incipit ibi: simile igitur et cetera. Dicit ergo primo quod non pertinet ad scientiam naturalem intendere ad perscrutandum de hac opinione, si ens est unum et immobile. Iam enim ostensum est quod non differt secundum intentionem antiquorum philosophorum, ponere unum principium immobile, et ponere unum ens immobile. Et quod improbare hanc opinionem ad naturalem non pertineat, sic ostendit. Ad geometriam non pertinet inducere rationem contra destruentem sua principia; sed hoc vel pertinet ad aliquam aliam scientiam particularem (si tamen geometria sit subalternata alicui particulari scientiae; sicut musica arithmeticae subalternatur, ad quam pertinet disputare contra negantem principia musicae); vel hoc pertinet ad scientiam communem, scilicet ad logicam vel metaphysicam. Sed praedicta positio destruit principia naturae; quia si sit solum unum ens, et sic unum, scilicet immobile, ut sic ex eo fieri alia non possint, tolletur ratio principii; quia omne principium aut est principium alicuius aut aliquorum. Ad positionem igitur principii sequitur multitudo, quia aliud est principium et aliud id cuius est principium; qui igitur negat multitudinem, tollit principia: non igitur debet contra hanc positionem disputare naturalis.	15. Next where he says, ‘Now to investigate ...’ (184 b 25), he shows that it does not pertain to natural science to disprove some of these opinions. And concerning this he makes two points. First he shows that it does not pertain to natural science to disprove the opinion of Parmenides and Melissus. Secondly, where he says, ‘At the same time the holders of the theory...’ (185 a 18),2 he gives a reason why it is useful to the present work to disprove this opinion. Concerning the first part he makes two points. First he shows that it does not pertain to natural science to disprove the aforesaid opinion. Secondly, where he says, ‘... or like refuting ...’ (185 a 8 #17), he shows that it does not pertain to natural science to resolve the arguments which are brought forth to prove this opinion. He establishes his first point with two arguments, the second , of which begins where he says, ‘To inquire therefore ...’ (185 a 5 #16). He says, therefore, that it does not pertain to natural science to undertake a thorough consideration of the opinion whether being is one and immobile. For it has already been shown that there is no difference, according to the intention of the ancient philosophers, whether we hold one immobile principle or one immobile being. And that it should not pertain to natural science to disprove this opinion he shows as follows. It does not pertain to geometry to bring forth reasons against an argument which destroys its principles. Rather, this either pertains to some other particular science (if, indeed, geometry is subalternated to some particular science, such as music is subalternated to arithmetic, to which it pertains to dispute against any position denying the principles of music), or it pertains to a common science such as logic or metaphysics. But the aforesaid position destroys the principles of nature. For if there is only one being, and if this being is immobile, such that from it others cannot come to be, then the very nature of a principle is taken away. For every principle is either a principle of some thing or of some things. Therefore, if we posit a principle, a multiplicity follows, because one is the principle and the other is that of which it is the principle. Whoever, therefore, denies multiplicity removes principles. Therefore natural science ought not to argue against this position.
lib. 1 l. 2 n. 5 Deinde cum dicit: simile igitur etc., ostendit idem alia ratione. Non enim requiritur ab aliqua scientia ut inducat rationem contra opiniones manifeste falsas et improbabiles; nam quolibet proferente contraria opinionibus sapientis solicitum esse, stultum est, ut dicitur I Topic. Hoc est ergo quod dicit, quod intendere ad perquirendum si ens est sic unum, scilicet immobile, simile est ac si disputaretur contra quamlibet aliam positionem improbabilem, ut puta contra positionem Heracliti, qui dixit omnia semper moveri et nihil esse verum; vel contra positionem alicuius qui diceret quod totum ens est unus homo, quae quidem positio esset omnino improbabilis. Et tamen qui ponit esse ens unum tantum immobile, cogitur ponere totum ens esse aliquod unum. Sic igitur patet quod non est naturalis scientiae contra hanc positionem disputare.	16. Next where he says, ‘To inquire therefore...’(185 a 5), he shows the same point with another argument. It is not required of any science that it bring forth arguments against manifestly false and improbable opinions. For to worry about one who offers positions contrary to the opinions of the wise is stupid, as is said in Topics, I:11. He says, therefore, that to undertake a thorough consideration of the question whether being is one, and hence immobile, is like arguing against any other improbable position. For example, it is like arguing against the position of Heraclitus, who said that all things are always moved and that nothing is true; or against the position of one who would say that the whole of being is one man, which position, indeed, would be altogether improbable. And indeed whoever holds being to be only one immobile thing is forced to hold that the whole of being is some one thing. It is clear, therefore, that it does not belong to natural science to argue against this position.
lib. 1 l. 2 n. 6 Deinde cum dicit: aut solvere etc., ostendit quod non est naturalis etiam solvere praedictorum philosophorum rationes. Et hoc per duas rationes, quarum secunda ponitur ibi: nobis autem subiiciantur et cetera. Probat ergo primo propositum per hoc quod non exigitur in aliqua scientia ut solvantur rationes sophisticae, quae manifestum defectum habent vel formae vel materiae. Et hoc est quod dicit, quod simile est intendere ad improbabiles rationes aut etiam solvere rationem litigiosam, idest sophisticam. Hoc autem quod sint sophisticae, habent utraeque rationes et Melissi et Parmenidis: peccant enim in materia, unde dicit quod falsa recipiunt, idest falsas propositiones assumunt; et peccant in forma, unde dicit quod non syllogizantes sunt. Sed ratio Melissi est magis onerosa, idest vana et fatua, et non habens defectum, idest non inducens dubitationem: et hoc infra ostendetur. Non est autem inconveniens si uno inconvenienti dato alia sequantur. Sic igitur concludi potest quod non requiritur a philosopho naturali quod solvat huius rationes.	17. Next when he says, ‘... or like refuting ...’ (185 a 8), he shows that it does not belong to natural science even to resolve the arguments of the aforementioned philosophers. And this for two reasons, the second of which begins where he says, ‘We physicists ...’ (185 a 13 #18). First he proves his position by pointing out that it is not incumbent upon any science to resolve sophistic arguments which have an obvious defect of form or matter. He says that to deal with improbable arguments is like solving a contentious or sophistic argument. But each argument of both Melissus and Parmenides is sophistic, for they err in matter, whence he says that they have accepted what is false, i.e., they assume false propositions, and they err in form, whence he says that they are not syllogizing. But the position of Melissus is much worse, i.e., more vain and foolish and does not cause any difficulty. This will be shown below [L 5]. Moreover, it is not inconsistent that given one inconsistency another should follow. Therefore it can be concluded that it is not required of the philosopher of nature that he resolve the arguments of this man.
lib. 1 l. 2 n. 7 Deinde cum dicit: nobis autem subiiciantur etc., ponit secundam rationem ad idem: quae talis est. In scientia naturali supponitur quod naturalia moveantur vel omnia vel quaedam: quod dicit quia de quibusdam est dubium si moventur et qualiter moventur, puta de anima, de centro terrae, de polo caeli, et formis naturalibus, et aliis huiusmodi. Et quod naturalia moveantur, potest manifestum esse ex inductione; quia ad sensum apparet quod res naturales moventur. Est autem necessarium motum supponi in scientia naturali, sicut necessarium est supponi naturam, in cuius definitione ponitur motus; est enim natura principium motus, ut infra dicetur. Hoc autem habito, quod motus supponatur in scientia naturali, ulterius procedit ad propositum ostendendum per hoc quod non omnes rationes sunt solvendae in aliqua scientia, sed solum illae quae concludunt aliquod falsum ex principiis illius scientiae: quaecumque vero non concludunt ex principiis scientiae, sed ex contrariis principiorum, non solvuntur in illa scientia. Et hoc probat per exemplum in geometricis dicens: ut tetragonismum, idest quadraturam circuli, hunc quidem qui est per decisiones circumferentiae, dissolvere pertinet ad geometram, quia nihil supponit contrarium principiis scientiae. Voluit enim quidam invenire quadratum aequale circulo dividendo circumferentiam circuli in multas partes, et singulis partibus supponendo lineas rectas: et sic, inveniendo aliquam figuram sicut rectilineam aequalem alicui illarum figurarum quae continentur a decisione circumferentiae et corda, aut pluribus aut omnibus, aestimabat se invenisse figuram rectilineam aequalem toti circulo, cui facile erat invenire quadratum aequale per principia geometriae: et sic putabat se invenire posse quadratum aequale circulo. Sed non sufficienter argumentabatur: quia licet illae decisiones consumerent totam circumferentiam circuli, non tamen figurae contentae a decisione circumferentiae et lineis rectis, comprehendebant totam superficiem circularem. Sed dissolvere quadraturam Antiphontis, non pertinet ad geometram, quia utebatur contrariis principiorum geometriae. Describebat enim in circulo aliquam figuram rectilineam, puta quadratum, et dividebat arcus quibus subtendebantur latera quadrati, singulos in duo media, et a punctis decisionum ducebat lineam rectam ad omnes angulos quadrati; et sic resultabat in circulo figura octo angulorum, quae plus accedebat ad aequalitatem circuli quam quadratum. Iterum dividebat arcus quibus subtendebantur latera figurae octo angulorum, singulos in duo media; et sic ducendo lineas rectas a punctis decisionum ad angulos praedictae figurae, resultabat figura sedecim angulorum, quae adhuc plus accedebat ad aequalitatem circuli. Semper ergo dividendo arcus, et ducendo lineas rectas ad angulos figurae praeexistentis, consurgit figura propinquius se habens ad aequalitatem circuli. Dicebat autem quod non est procedere in infinitum in decisione arcuum: erit ergo devenire ad aliquam figuram rectilineam aequalem circulo, cui poterit quadratum aequari. Quia igitur supponebat quod arcus non semper dividuntur in duo media, quod est contrarium principiis geometriae, huiusmodi rationem dissolvere non pertinet ad geometram. Quia igitur rationes Parmenidis et Melissi supponunt ens esse immobile, ut infra patebit; hoc autem est contra principia supposita in scientia naturali; sequitur quod solvere huiusmodi rationes, non pertinet ad philosophum naturalem.	18. He sets forth the second argument for this where he says, ‘We physicists...’ (185 a 13). The argument is as follows. In natural science it is supposed that natural things are moved, either all or some of them. He says this because there is doubt whether some things are moved and how they are moved, for example, about the soul and the centre of the earth, and the pole of heaven, and about natural forms and other such things. But the fact that natural things are moved can be made clear from induction, for it is apparent to the sense that natural things are moved. It is as necessary that motion be supposed in natural science as it is necessary that nature be supposed. For motion is placed in the definition of nature, for nature is a principle of motion, as will be said below [II, L1]. Having established this point, that motion is supposed in natural science, he proceeds further to prove his position as follows. Not A arguments must be resolved in any science, but only those which conclude to something false from the principles of that science. Any arguments which do not reach their conclusions from the principles of the science, but from the contraries of these principles, are not resolved in that science. He proves this by an example taken from geometry saying that it pertains to geometry to resolve the problem of squaring, i.e., the squaring of a circle by dissecting the circumference, because this method supposes nothing contrary to the principles of the science of geometry. For somebody wished to find a square equal to a circle by dividing the circumference of the circle into many parts and placing straight lines in each part. And so by finding some figure, which was rectilinear, equal to some of the figures which were contained by the dissections of the circumference and the cords (either many or all), he thought he had found a rectilinear figure equal to the whole circle, to which it was easy to find an equal square through the principles of geometry. And thus he thought that he was able to find a square equal to a circle. But he did not argue well enough, for although these dissections used up the whole circumference of the circle, the figures contained by the dissections of the circumference and the straight lines did not encompass the whole circular surface. But to resolve the square of Antiphon does not pertain to geometry, because he used principles contrary to those of geometry. For he described in a circle a certain rectilinear figure, for example, a square. And he divided in half the arcs by which the sides of the square were subtended. And from the points of dissection he led straight lines to all the angles of the square. And then there resulted in the circle a figure of eight angles, which more closely approached equality with the circle than the square. Then he again divided in half the arcs by which the sides of the octagon were subtended, and thus by leading straight lines from the points of dissection to the angles of this figure there resulted a figure of sixteen angles, which still further approached equality with the circle. Therefore, by always dividing the arcs and leading straight lines to the angles of the figure already existing there will arise a figure very near to equality with the circle. He said, then, that it was impossible to proceed to infinity in the dissection of arcs. Therefore, it was necessary to arrive at some rectilinear figure equal to the circle to which some square could be equal. But, because he supposed that an arc is not always divisible in half, which is contrary to the principles of geometry, it does not pertain to geometry to resolve an argument of this sort. Therefore, because the arguments of Parmenides and Melissus suppose being to be immobile (as will be shown below [L5]), and since this is contrary to the principles supposed in natural science, it follows that it does not pertain to the natural philosopher to resolve arguments of this sort.
lib. 1 l. 2 n. 8 Deinde cum dicit: sed quoniam de natura etc., assignat rationem quare disputet contra praedictam positionem. Et dicit quod quia praedicti philosophi loquebantur de rebus naturalibus, licet non inducerent defectus, idest dubitationes naturales; utile est ad propositum disputare de huiusmodi opinionibus: quia etsi non sit scientiae naturalis disputare contra huiusmodi positiones, pertinet tamen ad philosophiam primam.	19. Next where he says, ‘At the same time ...’ (185 a 18), he states why he will argue against the aforementioned position. He says that because the philosophers mentioned above did speak of natural things, even though they did not create a problem (that is, in the sphere of natural science), it is useful for his present purpose to argue against opinions of this sort. For even though it does not pertain to natural science to argue against such positions, it does pertain to first philosophy.