Whether ingratitude is always a sin?

❌ Objection 1 : It seems that ingratitude is not always a sin. For Seneca says (De Benef. iii) that "he who does not repay a favor is ungrateful." But sometimes it is impossible to repay a favor without sinning, for instance if one man has helped another to commit a sin. Therefore, since it is not a sin to refrain from sinning, it seems that ingratitude is not always a sin.

❌ Objection 2 : Further, every sin is in the power of the person who commits it: because, according to Augustine (De Lib. Arb. iii; Retract. i), "no man sins in what he cannot avoid." Now sometimes it is not in the power of the sinner to avoid ingratitude, for instance when he has not the means of repaying. Again forgetfulness is not in our power, and yet Seneca declares (De Benef. iii) that "to forget a kindness is the height of ingratitude." Therefore ingratitude is not always a sin.

❌ Objection 3 : Further, there would seem to be no repayment in being unwilling to owe anything, according to the Apostle (Rm. 13:8), "Owe no man anything." Yet "an unwilling debtor is ungrateful," as Seneca declares (De Benef. iv). Therefore ingratitude is not always a sin.