Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 18, a. 2 ; a. 4, ad 3 ; a. 6 ; a. 7, ad 1 ; a. 10 ; q. 1, a. 3, ad 3 ; De Malo, q. 2, a. 6, ad 3.

148. Principle I. The morally considered object gives human acts not only generic but also specific morality.

Declaration. The sense is: The object not only makes the essential distinction between good and bad, and constitutes the supreme species of goodness and malice in human acts, but also the lowest species by which various good or bad acts are distinguished from one another.

It is proved: A moral act is essentially a motion to the morally considered object, as to a terminus. But every motion essentially has its lowest species from the terminus. Therefore every human act has its lowest moral species from the morally considered object. — And therefore according as objects say diverse fittingness with reason or opposition, various species of good acts are distinguished (e. g., love of God and of neighbor, faith and charity, fortitude and temperance), or of bad acts (e. g., homicide and theft, blasphemy and detraction, lust and anger).

Against this doctrine there is no obstacle from 1) the circumstance's being able to constitute the lowest moral species in a human act, because then it enters into the object, and becomes the principal condition of it and, as it were, the specific difference of the human act, as will be explained below, art. 2;

2. the human act's receiving its species from the end, because a) the end is the object of the will; b) with respect to the external commanded act, the end of the work is the same as the object, the end of the agent added is a circumstance adding species, which is considered by the agent as the accessory condition of the object coming extrinsically, insofar as the act is done under the influence of the will whose object is the end of the agent (cf. art. 3).

149. Principle II. One and the same moral act can have multiple species of morality.

It is proved: 1) This is not verified of a human act according to physical being, because a physical entity is specified by a natural form which is determined to one thing, and therefore is of one species; but according to moral being, an act is specified by the object apprehended by reason, which is not determined to one thing, but under different consideration can be referred to different species according to the moral conditions supervening, whether the species are of themselves subordinated to one another, or are disparate, as if theft is ordered to drunkenness (a. 7, ad 1). Thus to take another's property from a sacred place includes a different specific repugnance to the order of reason, which dictates that an injury not be done to a sacred place; and yet the object remains one, but composed of several.

2. Moral being accrues as a quality to the physical being itself, and therefore just as one physical thing can be of different species

Summa Theologiae Moralis I — 10 of perfection or defect according to accidents, e. g., the same man white and musical, blind and deaf, so one physical act can pertain to several moral species. Whence nothing prevents the same act from being in different species of virtue or sin.

150. Principle III. One and the same moral act cannot, however, be at one and the same time good and bad.

It is proved: For an act to be simply good, goodness is required from every part; for it to be simply bad, malice from any part is sufficient. Therefore.

And nevertheless, an act evil from one part is not thereby deprived of every goodness coming from other sources: thus an act good according to species can be bad by reason of a circumstance, or an act good according to species and circumstances can be ordered to a bad end, because, as S. Thomas says, « the posterior being removed, the prior nevertheless remains » (I Sent., d. 41, q. 1, a. 2 (Cf. I-II, q. 18, a. 4, ad 3).— It is excepted if the act is done from the sole or total cause of evil, because then no goodness is intended nor contracted, but the act is considered as a mere means of evil, insofar as the object is considered as altogether evil.