Reply Obj. 2:  Jerome ascribes hatred of vice to the irascible faculty, not by reason of hatred, which is properly a concupiscible passion; but on account of the struggle, which belongs to the irascible power.

Reply Obj. 3:  Good, inasmuch as it is delightful, moves the concupiscible power.  But if it prove difficult to obtain, from this very fact it has a certain contrariety to the concupiscible power:  and hence the need of another power tending to that good.  The same applies to evil.  And this power is the irascible faculty.  Consequently the concupiscible passions are specifically different from the irascible passions. ________________________

SECOND ARTICLE [I-II, Q. 23, Art. 2]

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

Objection 1:  It would seem that the contrariety of the irascible passions is based on no other contrariety than that of good and evil.  For the irascible passions are ordained to the concupiscible passions, as stated above (A. 1, ad 1).  But the contrariety of the concupiscible passions is no other than that of good and evil; take, for instance, love and hatred, joy and sorrow.  Therefore the same applies to the irascible passions.

Obj. 2:  Further, passions differ according to their objects; just as movements differ according to their termini.  But there is no other contrariety of movements, except that of the termini, as is stated in Phys. v, 3.  Therefore there is no other contrariety of passions, save that of the objects.  Now the object of the appetite is good or evil.  Therefore in no appetitive power can there be contrariety of passions other than that of good and evil.

Obj. 3:  Further, “every passion of the soul is by way of approach and withdrawal,” as Avicenna declares in his sixth book of Physics. Now approach results from the apprehension of good; withdrawal, from the apprehension of evil:  since just as “good is what all desire” (Ethic. i, 1), so evil is what all shun.  Therefore, in the passions of the soul, there can be no other contrariety than that of good and evil.

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.