Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that a habit cannot diminish. Because a habit is a simple quality and form. Now a simple thing is possessed either wholly or not at all. Therefore although a habit can be lost it cannot diminish.

Objection 2: Further, if a thing is befitting an accident, this is by reason either of the accident or of its subject. Now a habit does not become more or less intense by reason of itself; else it would follow that a species might be predicated of its individuals more or less. And if it can become less intense as to its participation by its subject, it would follow that something is accidental to a habit, proper thereto and not common to the habit and its subject. Now whenever a form has something proper to it besides its subject, that form can be separate, as stated in De Anima i, text. 13. Hence it follows that a habit is a separable form; which is impossible.

Objection 3: Further, the very notion and nature of a habit as of any accident, is inherence in a subject: wherefore any accident is defined with reference to its subject. Therefore if a habit does not become more or less intense in itself, neither can it in its inherence in its subject: and consequently it will be nowise less intense.

On the contrary, It is natural for contraries to be applicable to the same thing. Now increase and decrease are contraries. Since therefore a habit can increase, it seems that it can also diminish.

I answer that, Habits diminish, just as they increase, in two ways, as we have already explained (Question 52, Article 1). And since they increase through the same cause as that which engenders them, so too they diminish by the same cause as that which corrupts them: since the diminishing of a habit is the road which leads to its corruption, even as, on the other hand, the engendering of a habit is a foundation of its increase.

Reply to Objection 1: A habit, considered in itself, is a simple form. It is not thus that it is subject to decrease; but according to the different ways in which its subject participates in it. This is due to the fact that the subject's potentiality is indeterminate, through its being able to participate a form in various ways, or to extend to a greater or a smaller number of things.

Reply to Objection 2: This argument would hold, if the essence itself of a habit were nowise subject to decrease. This we do not say; but that a certain decrease in the essence of a habit has its origin, not in the habit, but in its subject.

Reply to Objection 3: No matter how we take an accident, its very notion implies dependence on a subject, but in different ways. For if we take an accident in the abstract, it implies relation to a subject, which relation begins in the accident and terminates in the subject: for "whiteness is that whereby a thing is white." Accordingly in defining an accident in the abstract, we do not put the subject as though it were the first part of the definition, viz. the genus; but we give it the second place, which is that of the difference; thus we say that "simitas" is "a curvature of the nose." But if we take accidents in the concrete, the relation begins in the subject and terminates in the concrete, the relation begins in the subject and terminates at the accident: for "a white thing" is "something that has whiteness." Accordingly in defining this kind of accident, we place the subject as the genus, which is the first part of a definition; for we say that a "simum" is a "snub-nose." Accordingly whatever is befitting an accident on the part of the subject, but is not of the very essence of the accident, is ascribed to that accident, not in the abstract, but in the concrete. Such are increase and decrease in certain accidents: wherefore to be more or less white is not ascribed to whiteness but to a white thing. The same applies to habits and other qualities; save that certain habits and other qualities; save that certain habits increase or diminish by a kind of addition, as we have already clearly explained (Question 52, Article 2).

Articulus 2

Argumentum 1

Ad secundum sic proceditur. Videtur quod habitus diminui non possit. Habitus enim est quaedam qualitas et forma simplex.

Simplex autem aut totum habetur, aut totum amittitur.

Ergo habitus, etsi corrumpi possit, diminui non potest.

Argumentum 2

Praeterea, omne quod convenit accidenti, convenit eidem secundum se, vel ratione sui subiecti. Habitus autem secundum seipsum non intenditur et remittitur, alioquin sequeretur quod aliqua species de suis individuis praedicaretur secundum magis et minus. Si igitur secundum participationem subiecti diminui possit, sequeretur quod aliquid accidat habitui proprium, quod non sit commune ei et subiecto.

Cuicumque autem formae convenit aliquid proprium praeter suum subiectum, illa forma est separabilis, ut dicitur in I de anima.

Sequitur ergo quod habitus sit forma separabilis, quod est impossibile.

Argumentum 3

Praeterea, ratio et natura habitus, sicut et cuiuslibet accidentis, consistit in concretione ad subiectum, unde et quodlibet accidens definitur per suum subiectum. Si igitur habitus secundum seipsum non intenditur neque remittitur, neque etiam secundum concretionem sui ad subiectum diminui poterit. Et ita nullo modo diminuetur.

Sed Contra

Sed contra est quod contraria nata sunt fieri circa idem.

Augmentum autem et diminutio sunt contraria. Cum igitur habitus possit augeri, videtur quod etiam possit diminui.

Corpus

Respondeo dicendum quod habitus dupliciter diminuuntur, sicut et augentur, ut ex supradictis patet.

Et sicut ex eadem causa augentur ex qua generantur, ita ex eadem causa diminuuntur ex qua corrumpuntur, nam diminutio habitus est quaedam via ad corruptionem, sicut e converso generatio habitus est quoddam fundamentum augmenti ipsius.

Ad 1

Ad primum ergo dicendum quod habitus secundum se consideratus, est forma simplex, et secundum hoc non accidit ei diminutio, sed secundum diversum modum participandi, qui provenit ex indeterminatione potentiae ipsius participantis, quae scilicet diversimode potest unam formam participare, vel quae potest ad plura vel ad pauciora extendi.

Ad 2

Ad secundum dicendum quod ratio illa procederet, si ipsa essentia habitus nullo modo diminueretur. Hoc autem non ponimus, sed quod quaedam diminutio essentiae habitus non habet principium ab habitu, sed a participante.

Ad 3

Ad tertium dicendum quod, quocumque modo significetur accidens, habet dependentiam ad subiectum secundum suam rationem, aliter tamen et aliter. Nam accidens significatum in abstracto, importat habitudinem ad subiectum quae incipit ab accidente, et terminatur ad subiectum, nam albedo dicitur qua aliquid est album. Et ideo in definitione accidentis abstracti non ponitur subiectum quasi prima pars definitionis, quae est genus; sed quasi secunda, quae est differentia; dicimus enim quod simitas est curvitas nasi. Sed in concretis incipit habitudo a subiecto, et terminatur ad accidens, dicitur enim album quod habet albedinem. Propter quod in definitione huiusmodi accidentis ponitur subiectum tanquam genus, quod est prima pars definitionis, dicimus enim quod simum est nasus curvus.

Sic igitur id quod convenit accidentibus ex parte subiecti, non autem ex ipsa ratione accidentis, non attribuitur accidenti in abstracto, sed in concreto. Et huiusmodi est intensio et remissio in quibusdam accidentibus, unde albedo non dicitur magis et minus, sed album. Et eadem ratio est in habitibus et aliis qualitatibus, nisi quod quidam habitus augentur vel diminuuntur per quandam additionem, ut ex supradictis patet.