Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that there is nothing voluntary in human acts. For that is voluntary "which has its principle within itself." as Gregory of Nyssa , Damascene (De Fide Orth. ii, 24), and Aristotle (Ethic. iii, 1) declare. But the principle of human acts is not in man himself, but outside him: since man's appetite is moved to act, by the appetible object which is outside him, and is as a "mover unmoved" (De Anima iii, 10). Therefore there is nothing voluntary in human acts.

Objection 2: Further, the Philosopher (Phys. viii, 2) proves that in animals no new movement arises that is not preceded by a motion from without. But all human acts are new, since none is eternal. Consequently, the principle of all human acts is from without: and therefore there is nothing voluntary in them.

Objection 3: Further, he that acts voluntarily, can act of himself. But this is not true of man; for it is written (Jn. 15:5): "Without Me you can do nothing." Therefore there is nothing voluntary in human acts.

On the contrary, Damascene says (De Fide Orth. ii) that "the voluntary is an act consisting in a rational operation." Now such are human acts. Therefore there is something voluntary in human acts.

I answer that, There must needs be something voluntary in human acts. In order to make this clear, we must take note that the principle of some acts or movements is within the agent, or that which is moved; whereas the principle of some movements or acts is outside. For when a stone is moved upwards, the principle of this movement is outside the stone: whereas when it is moved downwards, the principle of this movement is in the stone. Now of those things that are moved by an intrinsic principle, some move themselves, some not. For since every agent or thing moved, acts or is moved for an end, as stated above (Question 1, Article 2); those are perfectly moved by an intrinsic principle, whose intrinsic principle is one not only of movement but of movement for an end. Now in order for a thing to be done for an end, some knowledge of the end is necessary. Therefore, whatever so acts or is moved by an intrinsic principle, that it has some knowledge of the end, has within itself the principle of its act, so that it not only acts, but acts for an end. On the other hand, if a thing has no knowledge of the end, even though it have an intrinsic principle of action or movement, nevertheless the principle of acting or being moved for an end is not in that thing, but in something else, by which the principle of its action towards an end is not in that thing, but in something else, by which the principle of its action towards an end is imprinted on it. Wherefore such like things are not said to move themselves, but to be moved by others. But those things which have a knowledge of the end are said to move themselves because there is in them a principle by which they not only act but also act for an end. And consequently, since both are from an intrinsic principle, to wit, that they act and that they act for an end, the movements of such things are said to be voluntary: for the word "voluntary" implies that their movements and acts are from their own inclination. Hence it is that, according to the definitions of Aristotle, Gregory of Nyssa, and Damascene , the voluntary is defined not only as having "a principle within" the agent, but also as implying "knowledge." Therefore, since man especially knows the end of his work, and moves himself, in his acts especially is the voluntary to be found.

Reply to Objection 1: Not every principle is a first principle. Therefore, although it is essential to the voluntary act that its principle be within the agent, nevertheless it is not contrary to the nature of the voluntary act that this intrinsic principle be caused or moved by an extrinsic principle: because it is not essential to the voluntary act that its intrinsic principle be a first principle. Yet again it must be observed that a principle of movement may happen to be first in a genus, but not first simply: thus in the genus of things subject to alteration, the first principle of alteration is a heavenly body, which is nevertheless, is not the first mover simply, but is moved locally by a higher mover. And so the intrinsic principle of the voluntary act, i.e. the cognitive and appetitive power, is the first principle in the genus of appetitive movement, although it is moved by an extrinsic principle according to other species of movement.

Reply to Objection 2: New movements in animals are indeed preceded by a motion from without; and this in two respects. First, in so far as by means of an extrinsic motion an animal's senses are confronted with something sensible, which, on being apprehended, moves the appetite. Thus a lion, on seeing a stag in movement and coming towards him, begins to be moved towards the stag. Secondly, in so far as some extrinsic motion produces a physical change in an animal's body, as in the case of cold or heat; and through the body being affected by the motion of an outward body, the sensitive appetite which is the power of a bodily organ, is also moved indirectly; thus it happens that through some alteration in the body the appetite is roused to the desire of something. But this is not contrary to the nature of voluntariness, as stated above (ad 1), for such movements caused by an extrinsic principle are of another genus of movement.

Reply to Objection 3: God moves man to act, not only by proposing the appetible to the senses, or by effecting a change in his body, but also by moving the will itself; because every movement either of the will or of nature, proceeds from God as the First Mover. And just as it is not incompatible with nature that the natural movement be from God as the First Mover, inasmuch as nature is an instrument of God moving it: so it is not contrary to the essence of a voluntary act, that it proceed from God, inasmuch as the will is moved by God. Nevertheless both natural and voluntary movements have this in common, that it is essential that they should proceed from a principle within the agent.

Articulus 1

Argumentum 1

Ad primum sic proceditur. Videtur quod in humanis actibus non inveniatur voluntarium. Voluntarium enim est cuius principium est in ipso; ut patet per Gregorium Nyssenum, et Damascenum, et Aristotelem.

Sed principium humanorum actuum non est in ipso homine, sed est extra, nam appetitus hominis movetur ad agendum ab appetibili quod est extra quod est sicut movens non motum, ut dicitur in III de anima.

Ergo in humanis actibus non invenitur voluntarium.

Argumentum 2

Praeterea, philosophus in VIII physic. Probat quod non invenitur in animalibus aliquis motus novus, qui non praeveniatur ab alio motu exteriori.

Sed omnes actus hominis sunt novi, nullus enim actus hominis aeternus est. Ergo principium omnium humanorum actuum est ab extra. Non igitur in eis invenitur voluntarium.

Argumentum 3

Praeterea, qui voluntarie agit, per se agere potest.

Sed hoc homini non convenit, dicitur enim Ioan. XV, sine me nihil potestis facere.

Ergo voluntarium in humanis actibus non invenitur.

Sed Contra

Sed contra est quod dicit Damascenus, in II libro, quod voluntarium est actus qui est operatio rationalis.

Tales autem sunt actus humani.

Ergo in actibus humanis invenitur voluntarium.

Corpus

Respondeo dicendum quod oportet in actibus humanis voluntarium esse. Ad cuius evidentiam, considerandum est quod quorundam actuum seu motuum principium est in agente, seu in eo quod movetur; quorundam autem motuum vel actuum principium est extra. Cum enim lapis movetur sursum, principium huius motionis est extra lapidem, sed cum movetur deorsum, principium huius motionis est in ipso lapide. Eorum autem quae a principio intrinseco moventur, quaedam movent seipsa, quaedam autem non. Cum enim omne agens seu motum agat seu moveatur propter finem, ut supra habitum est; illa perfecte moventur a principio intrinseco, in quibus est aliquod intrinsecum principium non solum ut moveantur, sed ut moveantur in finem. Ad hoc autem quod fiat aliquid propter finem, requiritur cognitio finis aliqualis. Quodcumque igitur sic agit vel movetur a principio intrinseco, quod habet aliquam notitiam finis, habet in seipso principium sui actus non solum ut agat, sed etiam ut agat propter finem. Quod autem nullam notitiam finis habet, etsi in eo sit principium actionis vel motus; non tamen eius quod est agere vel moveri propter finem est principium in ipso, sed in alio, a quo ei imprimitur principium suae motionis in finem. Unde huiusmodi non dicuntur movere seipsa, sed ab aliis moveri. Quae vero habent notitiam finis dicuntur seipsa movere, quia in eis est principium non solum ut agant, sed etiam ut agant propter finem. Et ideo, cum utrumque sit ab intrinseco principio, scilicet quod agunt, et quod propter finem agunt, horum motus et actus dicuntur voluntarii, hoc enim importat nomen voluntarii, quod motus et actus sit a propria inclinatione.

Et inde est quod voluntarium dicitur esse, secundum definitionem Aristotelis et Gregorii Nysseni et Damasceni, non solum cuius principium est intra, sed cum additione scientiae. Unde, cum homo maxime cognoscat finem sui operis et moveat seipsum, in eius actibus maxime voluntarium invenitur.

Ad 1

Ad primum ergo dicendum quod non omne principium est principium primum. Licet ergo de ratione voluntarii sit quod principium eius sit intra, non tamen est contra rationem voluntarii quod principium intrinsecum causetur vel moveatur ab exteriori principio, quia non est de ratione voluntarii quod principium intrinsecum sit principium primum. Sed tamen sciendum quod contingit aliquod principium motus esse primum in genere, quod tamen non est primum simpliciter sicut in genere alterabilium primum alterans est corpus caeleste, quod tamen non est primum movens simpliciter, sed movetur motu locali a superiori movente. Sic igitur principium intrinsecum voluntarii actus, quod est vis cognoscitiva et appetitiva, est primum principium in genere appetitivi motus, quamvis moveatur ab aliquo exteriori secundum alias species motus.

Ad 2

Ad secundum dicendum quod motus animalis novus praevenitur quidem ab aliquo exteriori motu quantum ad duo. Uno modo, inquantum per motum exteriorem praesentatur sensui animalis aliquod sensibile, quod apprehensum movet appetitum, sicut leo videns cervum per eius motum appropinquantem, incipit moveri ad ipsum. Alio modo, inquantum per exteriorem motum incipit aliqualiter immutari naturali immutatione corpus animalis, puta per frigus vel calorem; corpore autem immutato per motum exterioris corporis, immutatur etiam per accidens appetitus sensitivus, qui est virtus organi corporei; sicut cum ex aliqua alteratione corporis commovetur appetitus ad concupiscentiam alicuius rei. Sed hoc non est contra rationem voluntarii, ut dictum est huiusmodi enim motiones ab exteriori principio sunt alterius generis.

Ad 3

Ad tertium dicendum quod deus movet hominem ad agendum non solum sicut proponens sensui appetibile, vel sicut immutans corpus, sed etiam sicut movens ipsam voluntatem, quia omnis motus tam voluntatis quam naturae, ab eo procedit sicut a primo movente. Et sicut non est contra rationem naturae quod motus naturae sit a deo sicut a primo movente, inquantum natura est quoddam instrumentum dei moventis; ita non est contra rationem actus voluntarii quod sit a deo, inquantum voluntas a deo movetur. Est tamen communiter de ratione naturalis et voluntarii motus, quod sint a principio intrinseco.