As I’ve been studying Catholic Doctrine I’ve also been studying Calvanism/Reformed Theology.
Like many folks, I thought Total Depravity meant we are all “rotten to the core” and incapable of doing good things at all.
As I understand it. The difference between Catholic doctrine of original sin and the Reformed Doctrine of Total Depravity is the effect that original sin has on the spirit/soul of a person. Total Depravity means that, spiritually speaking, we are dead in our sinfulness, not just sick. It is not that we can’t do good things or be good people without Christ. It is that even “good things” we do without Christ, are tainted by sin because they are motivated by reasons other than the Glory of God. Good deeds done without Christ are “filthy rags” in God’s sight.