Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 77, a. 7; q. 20. a. 5; II-II, q. 43, a. 3; q. 46, a. 2, ad 2; q. 64, a. 7 et 8; q. 79. a. 3, ad 3; q. 150, a. 4.

62. Notions. — By reason of the mode in which the will is borne toward that object, the positive and direct voluntary is either 1° Voluntary in itself, when the will is borne directly toward that object, i.e., it immediately wills something in itself and simultaneously causes it by acting, whether as an end (for its own sake), e.g., when someone wills to kill an enemy, or as a means to an end (for the sake of another), e.g., when a thief wills to kill a traveler in order to take his money; — or 2° Voluntary in cause only, when the will is borne immediately toward the cause and not toward the effect, i.e., it does not will the effect in itself as an end or means, but nevertheless the effect itself proceeds from the will insofar as this wills and does something else with which it is joined as with a cause, e.g., when someone wills to get drunk, foreseeing that in drunkenness he will commit blasphemies, impurities, or homicide¹ The cause can be physical or moral, immediate or mediate, proximate or remote, a cause per se which is naturally suited to produce the effect, although by accident the effect can fail (thus excessive drink produces drunkenness), or a cause per accidens which not from its own nature but by the intervention of another can sometimes produce it (thus drunkenness, with a quarrel arising, produces homicide). More recent authors prefer to say direct and indirect voluntary; but they would better say immediate and mediate: for what proceeds through a positive cause, yet directly from the will².

63. Principles. That an effect be voluntary in its cause, it is required: 1° That the effect have been foreseen in some way, at least confusedly, as was said in no. 60, II: for nothing is willed unless it is foreknown;

2° That it could have been avoided, and therefore that the cause was freely posited or could have not been posited: for the effect is not more voluntary than its own cause;

3° That there be a nexus of causality between this freely placed cause and this effect; which a) is always verified of the cause per se if the two prior conditions are present: for he who wills the cause is deemed to will the effect which follows from it naturally and necessarily; b) is verified also of the cause per accidens provided that in addition the third condition be present, namely that the effect ought to have been avoided, or that there was present the obligation of not placing the cause, and indeed of not placing it lest the effect follow: for since the effect is not sufficiently contained in such a cause (unless through another cause) and hence no physical nexus is present with the effect, if the said obligation is lacking, every nexus of causality, even moral, between cause and effect is lacking, and hence the effect will not be willed nor voluntary in the cause, but only permitted. On the contrary, if one is bound not to place the cause lest the effect follow, and nonetheless places it, he is deemed morally and imputably to be the cause of this effect.

But if the aforesaid conditions are present, the axiom is verified: An evil effect foreseen in the cause communicates its malice to the cause, namely, if it can and ought to be avoided. For the effect, indeed, is only voluntary in the cause and is not imputed to praise, because it is not intended; but in order that it be imputed to blame, it is required that there be an obligation to avoid the cause lest the effect follow, for otherwise no precept regarding the effect would be violated.

64. Corollaries. — From the foregoing it follows: 1° That an effect that is voluntary can be in its cause non-voluntary in itself, if it is not intended; indeed, in itself involuntary, if it displeases, as if someone posits the cause of a killing (e.g., releasing an arrow with some foresight of the killing) and this is not intended or displeases, e.g., if he does not wish to kill but wishes to release the arrow without applying sufficient care lest he kill a man.

2° On the contrary, an effect can be willed in itself, if it pleases, desired or even intended, and yet not be voluntary, if it follows from a cause per accidens and the obligation to avoid it is lacking, because, e.g., a greater good effect which follows from the cause is also intended: for then the evil effect willed in itself is not voluntary, but is only permitted in the cause (Cf. n. 173).

Thus if someone digs a pit on his own land, far from the road, foreseeing and desiring that an enemy might fall into it; if it so happens, the accident is not voluntary for him, because his is only an accidental cause.

3° An effect, e.g., the sin of a neighbor, of which we in no way posit the cause in itself but only a bare occasion or condition, or an accidental cause, is not voluntary in its cause nor imputable, even if it be in itself willed and intended; unless, however, there be an obligation to avoid the effect: for our intention does not change an occasion into a cause, nor an accidental cause into a cause in itself.

Thus if someone takes from a miser a thing of small value, foreseeing or even intending that he, from grief, may grow weak or die, and it so happens, the weakness and death are not voluntary because he was merely the occasion or accidental cause of them, and in no way the per se cause.