---
title: "Summa Theologica, First Half"
author: "Thomas Aquinas"
translator: "Fathers of the English Dominican Province"
languages: [en]
shelf: "Medieval"
section: 472 of 1210
url: https://scriptura.si/works/thomas-aquinas-summa-theologica-first-half/472/
cite: "Thomas Aquinas, tr. Fathers of the English Dominican Province, Summa Theologica, First Half, section 472. Scriptura (scriptura.si), https://scriptura.si/works/thomas-aquinas-summa-theologica-first-half/472/"
---

# Summa Theologica, First Half

*Thomas Aquinas, tr. Fathers of the English Dominican Province*

God and creation, human action, law and grace, then faith, hope, charity and justice.

## 472. I–II · Q. 18, Art. 5: Whether a human action is good or evil in its species?

Source: https://scriptura.si/works/thomas-aquinas-summa-theologica-first-half/472/ · cite a paragraph as https://scriptura.si/works/thomas-aquinas-summa-theologica-first-half/472/#p-N

[¶0] Whether a human action is good or evil in its species?

[¶1] Objection 1: It would seem that good and evil in moral actions do not make a difference of species. For the existence of good and evil in actions is in conformity with their existence in things, as stated above (A 1). But good and evil do not make a specific difference in things; for a good man is specifically the same as a bad man. Therefore neither do they make a specific difference in actions.

[¶2] Objection 2: Further, since evil is a privation, it is a non-being. But non-being cannot be a difference, according to the Philosopher (Metaph. iii, 3). Since therefore the difference constitutes the species, it seems that an action is not constituted in a species through being evil. Consequently good and evil do not diversify the species of human actions.

[¶3] Objection 3: Further, acts that differ in species produce different effects. But the same specific effect results from a good and from an evil action: thus a man is born of adulterous or of lawful wedlock. Therefore good and evil actions do not differ in species.

[¶4] Objection 4: Further, actions are sometimes said to be good or bad from a circumstance, as stated above (A 3). But since a circumstance is an accident, it does not give an action its species. Therefore human actions do not differ in species on account of their goodness or malice.

[¶5] On the contrary, According to the Philosopher (Ethic ii. 1) "like habits produce like actions." But a good and a bad habit differ in species, as liberality and prodigality. Therefore also good and bad actions differ in species.

[¶6] I answer that, Every action derives its species from its object, as stated above (A 2). Hence it follows that a difference of object causes a difference of species in actions. Now, it must be observed that a difference of objects causes a difference of species in actions, according as the latter are referred to one active principle, which does not cause a difference in actions, according as they are referred to another active principle. Because nothing accidental constitutes a species, but only that which is essential; and a difference of object may be essential in reference to one active principle, and accidental in reference to another. Thus to know color and to know sound, differ essentially in reference to sense, but not in reference to the intellect.

[¶7] Now in human actions, good and evil are predicated in reference to the reason; because as Dionysius says (Div. Nom. iv), "the good of man is to be in accordance with reason," and evil is "to be against reason." For that is good for a thing which suits it in regard to its form; and evil, that which is against the order of its form. It is therefore evident that the difference of good and evil considered in reference to the object is an essential difference in relation to reason; that is to say, according as the object is suitable or unsuitable to reason. Now certain actions are called human or moral, inasmuch as they proceed from the reason. Consequently it is evident that good and evil diversify the species in human actions; since essential differences cause a difference of species.

[¶8] Reply to Objection 1: Even in natural things, good and evil, inasmuch as something is according to nature, and something against nature, diversify the natural species; for a dead body and a living body are not of the same species. In like manner, good, inasmuch as it is in accord with reason, and evil, inasmuch as it is against reason, diversify the moral species.

[¶9] Reply to Objection 2: Evil implies privation, not absolute, but affecting some potentiality. For an action is said to be evil in its species, not because it has no object at all; but because it has an object in disaccord with reason, for instance, to appropriate another's property. Wherefore in so far as the object is something positive, it can constitute the species of an evil act.

[¶10] Reply to Objection 3: The conjugal act and adultery, as compared to reason, differ specifically and have effects specifically different; because the other deserves praise and reward, the other, blame and punishment. But as compared to the generative power, they do not differ in species; and thus they have one specific effect.

[¶11] Reply to Objection 4: A circumstance is sometimes taken as the essential difference of the object, as compared to reason; and then it can specify a moral act. And it must needs be so whenever a circumstance transforms an action from good to evil; for a circumstance would not make an action evil, except through being repugnant to reason.

### I–II · Q. 18, Art. 6: Whether an action has the species of good or evil from its end?

[¶13] Whether an action has the species of good or evil from its end?

[¶14] Objection 1: It would seem that the good and evil which are from the end do not diversify the species of actions. For actions derive their species from the object. But the end is altogether apart from the object. Therefore the good and evil which are from the end do not diversify the species of an action.

[¶15] Objection 2: Further, that which is accidental does not constitute the species, as stated above (A 5). But it is accidental to an action to be ordained to some particular end; for instance, to give alms from vainglory. Therefore actions are not diversified as to species, according to the good and evil which are from the end.

[¶16] Objection 3: Further, acts that differ in species, can be ordained to the same end: thus to the end of vainglory, actions of various virtues and vices can be ordained. Therefore the good and evil which are taken from the end, do not diversify the species of action.

[¶17] On the contrary, It has been shown above (Q 1, A 3) that human actions derive their species from the end. Therefore good and evil in respect of the end diversify the species of actions.

[¶18] I answer that, Certain actions are called human, inasmuch as they are voluntary, as stated above (Q 1, A 1). Now, in a voluntary action, there is a twofold action, viz. the interior action of the will, and the external action: and each of these actions has its object. The end is properly the object of the interior act of the will: while the object of the external action, is that on which the action is brought to bear. Therefore just as the external action takes its species from the object on which it bears; so the interior act of the will takes its species from the end, as from its own proper object.

[¶19] Now that which is on the part of the will is formal in regard to that which is on the part of the external action: because the will uses the limbs to act as instruments; nor have external actions any measure of morality, save in so far as they are voluntary. Consequently the species of a human act is considered formally with regard to the end, but materially with regard to the object of the external action. Hence the Philosopher says (Ethic. v, 2) that "he who steals that he may commit adultery, is strictly speaking, more adulterer than thief."

[¶20] Reply to Objection 1: The end also has the character of an object, as stated above.

[¶21] Reply to Objection 2: Although it is accidental to the external action to be ordained to some particular end, it is not accidental to the interior act of the will, which act is compared to the external act, as form to matter.

[¶22] Reply to Objection 3: When many actions, differing in species, are ordained to the same end, there is indeed a diversity of species on the part of the external actions; but unity of species on the part of the internal action.