Thomas Aquinas - Summa Theologica, Part I-II (Pars Prima Secundae)

Obj. 3: Further, violent movement is that which is contrary to nature. But the movement of the will is sometimes contrary to nature; as is clear of the will's movement to sin, which is contrary to nature, as Damascene says (De Fide Orth. iv, 20). Therefore the movement of the will can be compelled.

On the contrary, Augustine says (De Civ. Dei v, 10) that what is done by the will is not done of necessity. Now, whatever is done under compulsion is done of necessity: consequently what is done by the will, cannot be compelled. Therefore the will cannot be compelled to act.

I answer that, The act of the will is twofold: one is its immediate act, as it were, elicited by it, namely, "to wish"; the other is an act of the will commanded by it, and put into execution by means of some other power, such as "to walk" and "to speak," which are commanded by the will to be executed by means of the motive power.

As regards the commanded acts of the will, then, the will can suffer violence, in so far as violence can prevent the exterior members from executing the will's command. But as to the will's own proper act, violence cannot be done to the will.

The reason of this is that the act of the will is nothing else than an inclination proceeding from the interior principle of knowledge: just as the natural appetite is an inclination proceeding from an interior principle without knowledge. Now what is compelled or violent is from an exterior principle. Consequently it is contrary to the nature of the will's own act, that it should be subject to compulsion and violence: just as it is also contrary to the nature of a natural inclination or movement. For a stone may have an upward movement from violence, but that this violent movement be from its natural inclination is impossible. In like manner a man may be dragged by force: but it is contrary to the very notion of violence, that he be dragged of his own will.

Reply Obj. 1: God Who is more powerful than the human will, can move the will of man, according to Prov. 21:1: "The heart of the king is in the hand of the Lord; whithersoever He will He shall turn it." But if this were by compulsion, it would no longer be by an act of the will, nor would the will itself be moved, but something else against the will.

Reply Obj. 2: It is not always a violent movement, when a passive subject is moved by its active principle; but only when this is done against the interior inclination of the passive subject. Otherwise every alteration and generation of simple bodies would be unnatural and violent: whereas they are natural by reason of the natural interior aptitude of the matter or subject to such a disposition. In like manner when the will is moved, according to its own inclination, by the appetible object, this movement is not violent but voluntary.

Reply Obj. 3: That to which the will tends by sinning, although in reality it is evil and contrary to the rational nature, nevertheless is apprehended as something good and suitable to nature, in so far as it is suitable to man by reason of some pleasurable sensation or some vicious habit. ________________________

FIFTH ARTICLE [I-II, Q. 6, Art. 5]

Whether Violence Causes Involuntariness?

Objection 1: It would seem that violence does not cause involuntariness. For we speak of voluntariness and involuntariness in respect of the will. But violence cannot be done to the will, as shown above (A. 4). Therefore violence cannot cause involuntariness.

Obj. 2: Further, that which is done involuntarily is done with grief, as Damascene (De Fide Orth. ii, 24) and the Philosopher (Ethic. iii, 5) say. But sometimes a man suffers compulsion without being grieved thereby. Therefore violence does not cause involuntariness.

Obj. 3: Further, what is from the will cannot be involuntary. But some violent actions proceed from the will: for instance, when a man with a heavy body goes upwards; or when a man contorts his limbs in a way contrary to their natural flexibility. Therefore violence does not cause involuntariness.

On the contrary, The Philosopher (Ethic. iii, 1) and Damascene (De Fide Orth. ii, 24) say that "things done under compulsion are involuntary."

I answer that, Violence is directly opposed to the voluntary, as likewise to the natural. For the voluntary and the natural have this in common, that both are from an intrinsic principle; whereas violence is from an extrinsic principle. And for this reason, just as in things devoid of knowledge, violence effects something against nature: so in things endowed with knowledge, it effects something against the will. Now that which is against nature is said to be "unnatural"; and in like manner that which is against the will is said to be "involuntary." Therefore violence causes involuntariness.

Reply Obj. 1: The involuntary is opposed to the voluntary. Now it has been said (A. 4) that not only the act, which proceeds immediately from the will, is called voluntary, but also the act commanded by the will. Consequently, as to the act which proceeds immediately from the will, violence cannot be done to the will, as stated above (A. 4): wherefore violence cannot make that act involuntary. But as to the commanded act, the will can suffer violence: and consequently in this respect violence causes involuntariness.

Reply Obj. 2: As that is said to be natural, which is according to the inclination of nature; so that is said to be voluntary, which is according to the inclination of the will. Now a thing is said to be natural in two ways. First, because it is from nature as from an active principle: thus it is natural for fire to produce heat. Secondly, according to a passive principle; because, to wit, there is in nature an inclination to receive an action from an extrinsic principle: thus the movement of the heavens is said to be natural, by reason of the natural aptitude in a heavenly body to receive such movement; although the cause of that movement is a voluntary agent. In like manner an act is said to be voluntary in two ways. First, in regard to action, for instance, when one wishes to be passive to another. Hence when action is brought to bear on something, by an extrinsic agent, as long as the will to suffer that action remains in the passive subject, there is not violence simply: for although the patient does nothing by way of action, he does something by being willing to suffer. Consequently this cannot be called involuntary.

Reply Obj. 3: As the Philosopher says (Phys. viii, 4) the movement of an animal, whereby at times an animal is moved against the natural inclination of the body, although it is not natural to the body, is nevertheless somewhat natural to the animal, to which it is natural to be moved according to its appetite. Accordingly this is violent, not simply but in a certain respect. The same remark applies in the case of one who contorts his limbs in a way that is contrary to their natural disposition. For this is violent in a certain respect, i.e. as to that particular limb; but not simply, i.e. as to the man himself. ________________________

SIXTH ARTICLE [I-II, Q. 6, Art. 6]

Whether Fear Causes Involuntariness Simply?

Objection 1: It would seem that fear causes involuntariness simply. For just as violence regards that which is contrary to the will at the time, so fear regards a future evil which is repugnant to the will. But violence causes involuntariness simply. Therefore fear too causes involuntariness simply.

Obj. 2: Further, that which is such of itself, remains such, whatever be added to it: thus what is hot of itself, as long as it remains, is still hot, whatever be added to it. But that which is done through fear, is involuntary in itself. Therefore, even with the addition of fear, it is involuntary.

Obj. 3: Further, that which is such, subject to a condition, is such in a certain respect; whereas what is such, without any condition, is such simply: thus what is necessary, subject to a condition, is necessary in some respect: but what is necessary absolutely, is necessary simply. But that which is done through fear, is absolutely involuntary; and is not voluntary, save under a condition, namely, in order that the evil feared may be avoided. Therefore that which is done through fear, is involuntary simply.