(b) Ignorance is consequent (after the act of the will), when it is voluntary, which may happen in different ways: first, when ignorance is affected, as when a person expressly desires to remain ignorant about his duties, so that he may have an excuse for his sins, or that he may not be disturbed in his evil life; secondly, when he neglects to acquire the knowledge he ought to possess, as when a hunter kills a man, thinking him an animal, because he took no pains to be sure before firing. (c) Ignorance is antecedent (before the act of the will), when it is not voluntary, and is the cause of the act that follows since the act would not have been done, if there had been knowledge. For example, a hunter who has used reasonable diligence to avoid accidents, kills a man whom he mistook for a deer. 27. With reference to the responsibility of the person who is ignorant, there are two kinds of ignorance. (a) Ignorance is invincible when it cannot be removed, even by the use of all the care that ordinarily prudent and conscientious persons would use in the circumstances. Thus, a person who has no suspicions of his ignorance, or who has tried in vain to acquire instruction about his duties, is invincibly ignorant. (b) Ignorance is vincible when it can be removed by the exercise of ordinary care. There are various degrees of this species of ignorance: first, it is merely vincible, when some diligence has been exercised, but not enough; secondly, it is crass or supine, when hardly any diligence has been used; thirdly, it is affected, when a person deliberately aims to continue in ignorance. 28. Influence of the Various Kinds of Ignorance on the Voluntariness of Acts.--(a) Ignorance of an act, whether as to its substance or quality, makes an act involuntary, when the ignorance itself is involuntary, as will be explained in paragraph 29. Hence, if we refer to ignorance that is not blameworthy and to the guilt of violating the law of God, we may say: “Ignorance excuses.” (b) Ignorance does not make an act involuntary before human law, unless the law itself presumes the ignorance or the ignorance is proved, as will be explained in the Question on Law (see 489 sqq.). For, when law is sufficiently promulgated or a fact pertains to one’s own self, the presumption is that ignorance does not exist, or that it is culpable. Hence, the general rule of law common to all forms of jurisprudence: “Ignorance does not excuse” (cfr. Canon 16 of the Code of Canon Law). 29. Effects of Concomitant, Consequent, and Antecedent Ignorance.--(a) Concomitant ignorance does not make an act involuntary, because it does not cause anything that is contrary to the will; but it does make the act that is performed non-voluntary, since what is unknown cannot be actually desired.