I answer that, Voluntary is what proceeds from the will.  Now one thing proceeds from another in two ways.  First, directly; in which sense something proceeds from another inasmuch as this other acts; for instance, heating from heat.  Secondly, indirectly; in which sense something proceeds from another through this other not acting; thus the sinking of a ship is set down to the helmsman, from his having ceased to steer.  But we must take note that the cause of what follows from want of action is not always the agent as not acting; but only then when the agent can and ought to act.  For if the helmsman were unable to steer the ship or if the ship’s helm be not entrusted to him, the sinking of the ship would not be set down to him, although it might be due to his absence from the helm.

Since, then, the will by willing and acting, is able, and sometimes ought, to hinder not-willing and not-acting; this not-willing and not-acting is imputed to, as though proceeding from, the will.  And thus it is that we can have the voluntary without an act; sometimes without outward act, but with an interior act; for instance, when one wills not to act; and sometimes without even an interior act, as when one does not will to act.

Reply Obj. 1:  We apply the word “voluntary” not only to that which proceeds from the will directly, as from its action; but also to that which proceeds from it indirectly as from its inaction.

Reply Obj. 2:  “Not to wish” is said in two senses.  First, as though it were one word, and the infinitive of “I-do-not-wish.”  Consequently just as when I say “I do not wish to read,” the sense is, “I wish not to read”; so “not to wish to read” is the same as “to wish not to read,” and in this sense “not to wish” implies involuntariness.  Secondly it is taken as a sentence:  and then no act of the will is affirmed.  And in this sense “not to wish” does not imply involuntariness.

Reply Obj. 3:  Voluntariness requires an act of knowledge in the same way as it requires an act of will; namely, in order that it be in one’s power to consider, to wish and to act.  And then, just as not to wish, and not to act, when it is time to wish and to act, is voluntary, so is it voluntary not to consider. ________________________

FOURTH ARTICLE [I-II, Q. 6, Art. 4]

Whether Violence Can Be Done to the Will?

Objection 1:  It would seem that violence can be done to the will.  For everything can be compelled by that which is more powerful.  But there is something, namely, God, that is more powerful than the human will.  Therefore it can be compelled, at least by Him.

Obj. 2:  Further, every passive subject is compelled by its active principle, when it is changed by it.  But the will is a passive force:  for it is a “mover moved” (De Anima iii, 10).  Therefore, since it is sometimes moved by its active principle, it seems that sometimes it is compelled.

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.