Whether original sin is concupiscence?

❌ Objection 1 : It would seem that original sin is not concupiscence. For every sin is contrary to nature, according to Damascene (De Fide Orth. ii, 4,30). But concupiscence is in accordance with nature, since it is the proper act of the concupiscible faculty which is a natural power. Therefore concupiscence is not original sin.

❌ Objection 2 : Further, through original sin "the passions of sins" are in us, according to the Apostle (Rm. 7:5). Now there are several other passions besides concupiscence, as stated above (Question [23], Article [4]). Therefore original sin is not concupiscence any more than another passion.

❌ Objection 3 : Further, by original sin, all the parts of the soul are disordered, as stated above (Article [2], Objection [3]). But the intellect is the highest of the soul's parts, as the Philosopher states (Ethic. x, 7). Therefore original sin is ignorance rather than concupiscence.