Reply Obj. 2:  The end is last in execution; but first in the intention of the reason, in regard to which moral actions receive their species.

Reply Obj. 3:  Difference is compared to genus as form to matter, inasmuch as it actualizes the genus.  On the other hand, the genus is considered as more formal than the species, inasmuch as it is something more absolute and less contracted.  Wherefore also the parts of a definition are reduced to the genus of formal cause, as is stated in Phys. ii, 3.  And in this sense the genus is the formal cause of the species; and so much the more formal, as it is more universal. ________________________

EIGHTH ARTICLE [I-II, Q. 18, Art. 8]

Whether Any Action Is Indifferent in Its Species?

Objection 1:  It would seem that no action is indifferent in its species.  For evil is the privation of good, according to Augustine (Enchiridion xi).  But privation and habit are immediate contraries, according to the Philosopher (Categor. viii).  Therefore there is not such thing as an action that is indifferent in its species, as though it were between good and evil.

Obj. 2:  Further, human actions derive their species from their end or object, as stated above (A. 6; Q. 1, A. 3).  But every end and every object is either good or bad.  Therefore every human action is good or evil according to its species.  None, therefore, is indifferent in its species.

Obj. 3:  Further, as stated above (A. 1), an action is said to be good, when it has its due complement of goodness; and evil, when it lacks that complement.  But every action must needs either have the entire plenitude of its goodness, or lack it in some respect.  Therefore every action must needs be either good or bad in its species, and none is indifferent.

On the contrary, Augustine says (De Serm.  Dom. in Monte ii, 18) that “there are certain deeds of a middle kind, which can be done with a good or evil mind, of which it is rash to form a judgment.”  Therefore some actions are indifferent according to their species.

I answer that, As stated above (AA. 2, 5), every action takes its species from its object; while human action, which is called moral, takes its species from the object, in relation to the principle of human actions, which is the reason.  Wherefore if the object of an action includes something in accord with the order of reason, it will be a good action according to its species; for instance, to give alms to a person in want.  On the other hand, if it includes something repugnant to the order of reason, it will be an evil act according to its species; for instance, to steal, which is to appropriate what belongs to another.  But it may happen that the object of an action does not include something pertaining to the order of reason; for instance, to pick up a straw from the ground, to walk in the fields, and the like:  and such actions are indifferent according to their species.