Authors/Ockham/Summa Logicae/Book I/Prologue

Latin	English
GUILLELMI DE OCKHAM SUMMA TOTIUS LOGICAE
[PROLOGUS FRATRIS ET MAGISTRI ADAM DE ANGLIA]	Prologue of the brother and master, Adam of England
Quam magnos veritatis sectatoribus afferat fructus sermocinalis scientia, quam logicam dicimus, multorum peritorum docet auctoritas, ratioque et experientia liquido comprobat et convincit. Unde Aristoteles, auctor praecipuus huius scientiae, nunc introductoriam methodum, nunc sciendi modum, nunc scientiam omnibus communem et viam veritatis appellat, dans ex his intelligere quod nulli ad sapientiam patet accessus nisi in scientia logica erudito. Averroes quoque, Aristotelis interpres, in Physicis dialecticam dicit esse "instrumentum discernendi verum a falso". Ipsa namque cuncta dubia definit, cunctas Scripturarum difficultates dissolvit et penetrat, ut testatur doctor egregius Augustinus.	The great fruits the science of language that we call “logic” brings for the followers of truth is taught by the authority of many experts, and reason and experience clearly confirm and prove it. Hence Aristotle, the principal author of this science, now calls it an introductory method, now a way of knowing, now a science common to all things, and the way to truth, giving us to understand by these remarks that the gateway to wisdom is open to no one except those educated in the science of logic. Also Averroes, the interpreter of Aristotle, says in his Commentary on the Physics that dialectic is 'the instrument for distinguishing between the true and the false'. For it resolves all doubts, dissolves and penetrates all the difficulties of Scripture, as the distinguished teacher Augustine testifies.
Cum enim duo sint actus sapientis ad alterum, "non mentiri de quibus novit et mentientem manifestare posse", ut scribitur in Elenchis, hoc autem fieri nequit absque discretione veri a falso, quod solum praestat haec methodus, luculenter apparet eam fore perutilem speculanti.	For since the actions of a wise person towards another are two - not to lie about what he knows, and to be able to make the liar manifest - as is written in the Sophistic Refutations, and this cannot happen without distinguishing the true from the false, which this method alone imparts, it is quite apparent that it is most useful for the one who speculates.
At vero haec sola facultatem praebet arguendi in omni problemate, omneque genus sophismatum dissolvere docet et demonstrationis medium invenire; mentem quoque a vinculis, quibus heu detinetur, absolvit atque libertati restituit. Quemadmodum enim vincula corporis membra ligant, necnon et officia ad quae instituta sunt prohibent, sic falsa argumenta et sophistica, ut docet Aristoteles, mentem nectunt. Similiter haec ars errorum caliginem detegit, actus dirigit humanae rationis instar lucis. Quinimmo et luci comparata invenitur prior. Sicut enim exclusa hac luce corporea actus humani aut nulli essent aut errabundi et saepe in praeiudicium operanti, sic absque huius facultatis peritia actus rationis.	This [art] alone offers the power of arguing about every problem, and teaches how to resolve every type of sophism and to find the middle [term] of a demonstration. It also frees the mind from the chains by which it is sadly held back, and restores it to liberty. For just as chains bind the members of the body and prevent the employment for which they were intended, so false arguments, and sophistical ones, fetter the mind, as Aristotle teaches. Similarly, this art lifts the fog of error and directs the acts of human reason in the manner of light. Indeed, compared to light, it is found to be prior. For just as, with physical light excluded, human actions would either be brought to nothing, or be aimless and often to the detriment of the one acting, so are acts of reason without skill in this power.
Cernimus namque plurimos, hac scientia praetermissa volentes intendere disciplinae, multifarie oberrare, errores varios docendo seminare, opiniones absurditate plenas confingere sine modo et ordine, et penitus non intelligibiles sermones prolixos texere et ordinare, simile quiddam patientes languidorum somniis ac fictionibus poetarum, rationes nullius omnino vigoris velut insolubiles ponderantes, vim propriae vocis ignorantes, qui eo periculosius errant quo se existimant prae aliis sapientes, audacter sine differentia falsa pro veris auditorum auribus ingerentes.	For we see many who, bypassing this science, [but] wishing to apply themselves to teaching, ramble about in many ways, disseminating various errors in [their] teaching, fabricating opinions full of absurdity with no measure or order, weaving and ordering together wholly unintelligible statements, as though suffering from the dreams of the languid or from the fictions of poets, considering reasoning of entirely no strength, as if they were incontestable, ignorant of the sense of their own speech. Who err more perilously, the more they esteem themselves wiser than others, rashly and indiscriminately heaping falsehoods in place of truths in the ears of their audience.
Praemissae itaque utilitatis, quam logica administrat, intuitu motus, praeclarus ille philosophus peripateticus Aristoteles eam artificiose composuit, quam quia propter obscuritatem Graeci sermonis in Latinum translati quis assequi sine temporis diuturnitate vix poterat, posteriores in his sufficienter edocti, varia opuscula ordinantes, iter facile ad eam satagentibus praebuerunt. Inter quos sane praecipuum existimo venerabilem doctorem fratrem Guillelmum, natione Anglicum, ordine Minorem, sed ingenii perspicacitate et doctrinae veritate sublimem.	Accordingly, moved by a consideration of the aforesaid usefulness that logic accomplishes, that distinguished Peripatetic philosopher Aristotle skillfully brought it together, although because of the obscurity of the Greek speech translated into Latin, one could scarcely follow it without spending some time, for which reason, later writers who were sufficiently educated in these matters, [by] composing various works, offered an easy route to [that art] to those intent on learning. Of these writers, I reasonably esteem the chief to be the venerable Doctor Friar William, an Englishman by nationality, a [friar] minor by order, but elevated in the sharp sightedness of his ability and in the truth of his teaching.
Siquidem hic doctor eximius, multorum saepe pulsatus precibus, totius huius methodi considerationem plene et limpide ac seriose composuit, initians a terminis ut a prioribus, deinde cetera prosecutus, usque ad finem perduxit.	Indeed, this extraordinary Doctor, often put upon by the entreaties of many, composed an investigation of the whole of this methodology, clearly and transparently and earnestly, starting from terms as from what is prior, and then proceeding to the rest until he arrived at the end.
Ad studiosos itaque, preces pro hoc praeclaro licet compendioso volumine geminantes, stilum dirigens, sed universis prodesse cupiens, exorsus est ita dicens:	Accordingly, directing his pen to the students redoubling their entreaties for this brilliant yet compendious volume, and yet wishing to benefit all, he began by saying:
[EPISTOLA PROOEMIALIS GUILLELMI DE OCKHAM]	[Preliminary letter by William of Ockham]
Dudum me, frater et amice carissime, tuis litteris studebas inducere ut aliquas regulas artis logicae in unum tractatum colligerem ac tuae dilectioni transmitterem. Cum igitur tui profectus ac veritatis amore inductus tuis precibus nequeam contraire, expertar quod hortaris remque mihi difficilem, sed tam tibi quam mihi, ut aestimo, fructuosam aggrediar.	Recently, brother friar and dearest friend, you were taking pains in your letters to lead me to gather together some rules of the art of logic into one treatise, and to send them to your esteemed person. Since, therefore, led on by love of your progress and for truth, I cannot go against your prayers, I shall try to do what you urge, something that is difficult for me, but fruitful for you as well as me, I think .
Logica enim est omnium artium aptissimum instrumentum, sine qua nulla scientia perfecte sciri potest, quae non more materialium instrumentorum usu crebro consumitur, sed per cuiuslibet alterius scientiae studiosum exercitium continuum recipit incrementum. Sicut enim mechanicus sui instrumenti perfecta carens notitia utendo eodem recipit pleniorem, sic in solidis logicae principiis eruditus dum, aliis scientiis operam impendit sollicite simul istius artis maiorem adquirit peritiam. Unde illud vulgare "ars logica labilis ars est" in solis sapientiale studium negligentibus locum reputo obtinere.	For logic is of all the arts the most fitting tool, without which no science can be completely known, which is not consumed by repeated use, in the manner of material tools, but rather admits continual increase through the diligent exercise of any other science. For just as a mechanic who lacks a complete knowledge of his tool acquires a fuller knowledge by using it, so one who is erudite in the solid principles of logic, while he diligently devotes his work to the other sciences, at the same time acquires a greater skill at this art. Hence, I regard the common saying, "The art of logic is a slippery art", as appropriate only for those pay no attention to the study of wisdom.
Logicae igitur considerationis continentiam prosequendo, a terminis ut a prioribus exordium assumendum est, deinde de propositionibus, postremo de syllogismis et aliis speciebus argumentationis perscrutatio subsequetur. Et quia plerumque contingit ante magnam experientiam logicae subtilitatibus theologiae aliarumque Facultatum iuniores impendere studium, ac per hoc in difficultates eis inexplicabiles incidunt, quae tamen aliis parvae sunt aut nullae, et in multiplices prolabuntur errores, veras demonstrationes tamquam sophismata respuentes et sophisticationes pro demonstrationibus recipientes, tractatum hunc duxi scribendum, nonnumquam in processu regulas per exempla tam philosophica quam theologica declarando.	Therefore, proceeding with the content of the investigation of logic, we must take our beginning with terms, as from what is prior, then there will follow the investigation of propositions, and finally the investigation of syllogisms and the other species of argumentation. And because it often happens that younger students of theology and other faculties overlay their study with subtleties, before they have much experience in logic, and through this fall into difficulties that are inexplicable to them - difficulties which are nonetheless little or nothing to others - and slip into manifold errors, casting off true demonstrations as if they were sophisms, and taking sophistry for demonstrations, I have been led to write this treatise, not infrequently by clarifying rules by both philosophical and theological examples, as I go along.