Which brings us to the practical core of depravity. Depravity is not defined so much by what is in us as it is by what is lacking. Depravity is emptiness, a lack of something necessary if one were to be other than depraved. When Adam and Eve sinned and they (and the offspring "in their loins") fell into depravity, what they fell into was a separation from God. Sin broke their oneness with God--it de-Spirited us, if you will.
Under such a view, our inability exists not so much in an absolute incapacity, but in that God is not sharing himself with us. In the natural, we are still creatures with a spirit (capacity) even though we are without the inspiration of the Spirit (ability). Depravity is what comes out of us when God is not rubbing off on us, so to speak. Such an inability is not so intrinsic to our nature that it would continue if God came near, any more than idle iron filings remain so if a magnet is passed near. There is no need to posit that a person would be unable to respond to God without first being reengineered.