Q: Whether the Contrariety of the Irascible Passions Is Based on the Contrariety of Good and Evil?

A: On the contrary,
Fear and daring are contrary to one another, as stated in Ethic. iii, 7. But fear and daring do not differ in respect of good and evil: because each regards some kind of evil. Therefore not every contrariety of the irascible passions is that of good and evil.

I answer that,
Passion is a kind of movement, as stated in Phys. iii, 3. Therefore contrariety of passions is based on contrariety of movements or changes. Now there is a twofold contrariety in changes and movements, as stated in
Phys.
v, 5. One is according to approach and withdrawal in respect of the same term: and this contrariety belongs properly to changes, i.e. to generation, which is a change
to being,
and to corruption, which is a change from being. The other contrariety is according to opposition of termini, and belongs properly to movements: thus whitening, which is movement from black to white, is contrary to blackening, which is movement from white to black.

Accordingly there is a twofold contrariety in the passions of the soul: one, according to contrariety of objects, i.e. of good and evil; the other, according to approach and withdrawal in respect of the same term. In the concupiscible passions the former contrariety alone is to be found; viz. that which is based on the objects: whereas in the irascible passions, we find both forms of contrariety. The reason of this is that the object of the concupiscible faculty, as stated above (A. 1), is sensible good or evil considered absolutely. Now good, as such, cannot be a term wherefrom, but only a term whereto, since nothing shuns good as such; on the contrary, all things desire it. In like manner, nothing desires evil, as such; but all things shun it: wherefore evil cannot have the aspect of a term whereto, but only of a term wherefrom. Accordingly every concupiscible passion in respect of good, tends to it, as love, desire and joy; while every concupiscible passion in respect of evil, tends from it, as hatred, avoidance or dislike, and sorrow. Wherefore, in the concupiscible passions, there can be no contrariety of approach and withdrawal in respect of the same object.

On the other hand, the object of the irascible faculty is sensible good or evil, considered not absolutely, but under the aspect of difficulty or arduousness. Now the good which is difficult or arduous, considered as good, is of such a nature as to produce in us a tendency to it, which tendency pertains to the passion of
hope;
whereas, considered as arduous or difficult, it makes us turn from it; and this pertains to the passion of
despair.
In like manner the arduous evil, considered as an evil, has the aspect of something to be shunned; and this belongs to the passion of
fear:
but it also contains a reason for tending to it, as attempting something arduous, whereby to escape being subject to evil; and this tendency is called
daring.
Consequently, in the irascible passions we find contrariety in respect of good and evil (as between hope and fear): and also contrariety according to approach and withdrawal in respect of the same term (as between daring and fear).

From what has been said the replies to the objections are evident.