In the previous post I summarized various evidence pertaining to a fundamental option in the sense of an orientation that changes through a series of acts. This post attempts a sketch that does justice to all of the evidence, as far as that is possible.
(1) A person who is strongly committed to the love of God and neighbor, to following the commandments, does not generally turn away from that path by a single choice and act taken in isolation, but by a gradual process of neglecting that love. This process may indeed culminate in a habitual state or act that is gravely contrary to charity, but the voluntariness of that habit or act must be referred to the persistent previous neglect of charity. An act objectively contrary to charity performed by a person strongly committed to the love of charity, if it is not the culmination of previous acts, is probably not fully voluntary. Conversely, if an objectively disordered act truly is fully voluntary, it is probably the culmination of a long process of neglect of relationships to other human beings, to God, to oneself, and only as a culmination of this voluntary process is the evil of the act fully voluntary.
This position harmonizes with the qualification made by Persona Humana: "[The fundamental option] can be completely changed by particular acts, especially when, as often happens, these have been prepared for by previous more superficial acts" (Persona Humana, n. 10).
The flip side: just as an anomalous bad action performed by a virtuous person is probably not fully voluntary, so an occasional repentance of a person set upon vice could be a superficial repentance, that does not really involve full voluntary acceptance of God's love and full willingness to turn from sin.
(2) On the other hand, if a person is not strongly set on any particular goal, it does not seem impossible to frequently, and in a short period of time, change the goal that he does have, including changing from a life directed toward God to a life directed toward himself, by mortal sin, especially inasmuch as supernatural grace and charity, by a which a person is in the highest manner directed toward God, transcend human experience.
This view of moral life has practical consequences. It means, for example, that greater weight should be given to patterns of behavior than to individual acts–not that individual acts are unimportant, but that they are important inasmuch as they express the interior of a person, one's will, which is more surely expressed in the way one lives one's commitments and furthers one's relationships than in individual acts taken in isolation.