Whether some concupiscences are natural, and some not natural?

❌ Objection 1 : It would seem that concupiscences are not divided into those which are natural and those which are not. For concupiscence belongs to the animal appetite, as stated above (Article [1], ad 3). But the natural appetite is contrasted with the animal appetite. Therefore no concupiscence is natural.

❌ Objection 2 : Further, material differences makes no difference of species, but only numerical difference; a difference which is outside the purview of science. But if some concupiscences are natural, and some not, they differ only in respect of their objects; which amounts to a material difference, which is one of number only. Therefore concupiscences should not be divided into those that are natural and those that are not.

❌ Objection 3 : Further, reason is contrasted with nature, as stated in Phys. ii, 5. If therefore in man there is a concupiscence which is not natural, it must needs be rational. But this is impossible: because, since concupiscence is a passion, it belongs to the sensitive appetite, and not to the will, which is the rational appetite. Therefore there are no concupiscences which are not natural.