(b) Consequent ignorance cannot make an act entirely involuntary, since such ignorance is itself voluntary; but it does in a certain respect make an act involuntary, i.e., inasmuch as the act would not have been done save for the ignorance. (c) Antecedent ignorance makes an act entirely involuntary. 30. Effects of Invincible and Vincible Ignorance.--(a) Invincible ignorance, even of what pertains to the natural law, makes an act involuntary, since nothing is willed except what is understood. Hence, no matter how wrong an act is in itself, the agent is not guilty of formal sin (see 249), if he is invincibly ignorant of the malice involved. (b) Vincible ignorance does not make an act involuntary, since the ignorance itself is voluntary; hence, it does not excuse from sin. It does not even make an act less voluntary and less sinful, if the ignorance is affected in order that one may have an excuse; for such a state of mind shows that the person would act the same way, even though he had knowledge. 31. Vincible ignorance makes an act less voluntary and less sinful: (a) when the ignorance is not affected, for the voluntariness is measured by the knowledge, and knowledge here is lacking; (b) when the ignorance, though affected, was fostered only through fear that knowledge might compel a stricter way of life; for such a state of mind seems to show that one would not act the same way if one had knowledge. 32. Like to ignorance are the following: (a) error, which is a judgment not in agreement with the facts (e.g., Balbus, a young child, thinks stealing is lawful, because older persons are represented as stealing in the moving pictures); (b) forgetfulness, which is ignorance of what was once known (e.g., Titus made a study of his duties as a Catholic when he was young, but at present what he does not know about those duties is not inconsiderable); (c) inadvertence, which is a lack of attention to what is being done (e.g., Caius, who is absent-minded, sometimes gets his hair cut and goes away without paying, or takes money that does not belong to him). 33. The principles and conclusions given above with regard to ignorance will apply also to error, forgetfulness and inadvertence; for in all these cases the lack of actual knowledge at the moment an act is done, is either willed or not willed, and accordingly the act itself is either voluntary or not voluntary. In the examples mentioned above, Balbus does not will the guilt of theft, since he does not know it; but his elders do will that guilt, because they should know it. Titus is responsible for neglecting his duties, if he has forgotten them through his own neglect of them or other fault; otherwise, he is not responsible. Caius’ inattention is involuntary, if due to mental concentration or distraction, and if it is not desired by him; it is voluntary, if he is aware of it and cultivates it, or if he does not try to be more attentive to his duties.