Daily Lessons from St. Thomas

Aquinas Day By Day

213

Aquinas’s topic: logic of arguments: “said through itself,” modes 3 and 4

Scripture: Church calendar:  St. Patrick of Ireland

Aquinas’s text: Expositio libri Posteriorum , Bk. 1, lec. 10

Modes 1 and 2 of per se predications do not take us beyond the realm of definitions, that is, formulae that uncover essences.  Aristotle knew that in the Phaedo Plato had limited the “true causes” to what he would call formal and final causality, relegating material and efficient causes to being mere conditions, not true causes at all.  The Philosopher realized that scientific knowledge of the natural world requires demonstrations that bring universal knowledge down to singulars and also that make use of the full range of causality.  Br. Thomas here explains Aristotle’s per se mode 3, which is designed to make sure demonstrative arguments can apply scientific knowledge to individual cases.  He notes how different this mode is from the two previous modes, but unlike some contemporary commentators on Aristotle, he does not reject this mode.  Then he explains Aristotle’s per se mode 4, which opens demonstrative arguments up to all four kinds of causes, especially efficient causality, which is so important in the physical sciences.  

Then (73b5) he sets down another mode of that which is through itself (per se), as “through itself” signifies something in isolation, as when he says “it is through itself” of some particular in the genus of substance, which is not predicated of any subject.  The reason for this is that when I say “walking” or “white,” I do not signify walking or white as something remaining isolated “by itself,” since something else is understood to exist which is walking or white. But this does not happen in terms which signify “some this (hoc aliquid),” namely, in primary substances. For when one says “Socrates” or “Plato,” one does not understand that there is something else, over and above what they really are, which is their subject. Therefore, things which in this way are not predicated of any subject are through themselves (per se), but things which are said of a subject, namely, as being present in the subject, are accidents. For things said of a subject, as universals of their inferiors, are not always accidents. It is necessary to understand, however, that this mode is not a mode of predicating, but a mode of being present ([existendi).  Consequently, at the start he did not say that they are said through themselves (per se), but that they are through themselves (per se sunt).

Then (73b10) he sets down the fourth mode, according to which the preposition “through (per)” designates a relation of efficient cause or of some other kind of cause. Therefore, he says that whatever is in anything because of itself (propter seipsum), is said of it through itself (per se), but whatever is not in something because of itself is said of it accidentally (per accidens), as when I say, “While he was walking, there was lightning.” For it is not because he walks that there is lightning, but this is said by coincidence. But if what is predicated is in a subject because of itself, it is in it through itself (per se), as when we say, “Having been slaughtered, it died.” For it is obvious that because the animal was slaughtered, it died, and it is not a mere coincidence that the thing slaughtered died.

Deinde cum dicit: amplius quod non etc., ponit alium modum eius, quod est per se, prout per se significat aliquid solitarium, sicut dicitur quod per se est aliquod particulare, quod est in genere substantiae, quod non praedicatur de aliquo subiecto. Et huius ratio est, quia cum dico, ambulans vel album, non significo ambulans vel album, quasi aliquid per se solitarium existens, cum intelligatur aliquid aliud esse quod sit ambulans vel album. Sed in his, quae significant hoc aliquid, scilicet in primis substantiis, hoc non contingit. Cum enim dicitur Socrates vel Plato, non intelligitur quod sit aliquid alterum, quam id quod vere ipsa sunt, quod scilicet sit subiectum eorum. Sic igitur hoc modo quae non praedicantur de subiecto sunt per se, quae vero dicuntur de subiecto, scilicet sicut in subiecto existentia, accidentia sunt. Nam quae dicuntur de subiecto, sicut universalia de inferioribus, non semper accidentia sunt. Sciendum est autem quod iste modus non est modus praedicandi, sed modus existendi. Unde etiam in principio non dixit, per se dicuntur, sed, per se sunt.

 

Deinde cum dicit: item alio modo etc., ponit quartum modum, secundum quod haec praepositio per designat habitudinem causae efficientis vel cuiuscunque alterius. Et ideo dicit quod quidquid inest unicuique propter seipsum, per se dicitur de eo; quod vero non propter seipsum inest alicui, per accidens dicitur, sicut cum dico: hoc ambulante coruscat. Non enim propter id quod ambulat, coruscavit; sed hoc dicitur secundum accidens. Si vero quod praedicatur insit subiecto propter seipsum, per se inest, ut si dicamus quod interfectum interiit: manifestum est enim quod propter id quod illud interfectum est, interiit, et non est accidens quod interfectum interierit.

[Introductions and translations © R.E. Houser]

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