Article IV: On Ignorance

S. Th. I-II, q. 6, a. 8; q. 19, a. 6; q. 76.

80. Ignorance properly is the lack of knowledge in a subject capable of it, for example of astronomy in a priest. It differs:

1. From nescience, which is the simple negation of knowledge in an incapable subject, for example in a child or a madman;

2. From error, which is not a mere lack but a positive act of the intellect judging a thing to be otherwise than it is; it arises from ignorance or rashness;

3. From inadvertence, which is the lack not indeed of habitual knowledge but of actual consideration;

4. From forgetfulness, which is the privation of knowledge previously had.

But since moralists treat only of due duties and undue sins, they often take ignorance more strictly, not indeed for a negation, but for the privation of knowledge which ought to be in someone, such as theology for a confessor. Hence some distinguish negative ignorance, privative ignorance, and even positive ignorance or ignorance of false disposition, if it includes error.

81. Ignorance is divided:

1. By reason of the object which is unknown, it is ignorance of law, whether natural or positive, whether divine or human, whether of the law itself or of the penalty joined to it, by which, namely, the existence or extension or sense of the law itself is unknown; and ignorance of fact, by which a fact or a concrete circumstance of fact determining the present application of the law is unknown.

Thus he who does not know that on the vigil of Pentecost one must fast, or that heretical books are prohibited, is in ignorance of law; he who does not advert that this day is the vigil of Pentecost, or that this book is heretical, is in ignorance of fact.

2. By reason of the subject or person who is ignorant, ignorance is invincible or vincible. Invincible or involuntary ignorance is that which could not be removed by moral diligence; but vincible or voluntary ignorance is that which could have been so removed.

Moral diligence is that which prudent persons are accustomed to employ, and which varies according to the various circumstances or quality of the business, person, place, etc.; for example, it will be greater in a priest for rightly executing his office than in a rustic, greater where there is question of the goods of life than of fortune, where there is question of notable harm to a third party than of a small one.

Vincible ignorance is inculpable if it ought not to have been removed; but culpable if it ought to have been. But moralists, attending only to due and undue things, use the words culpable and vincible indiscriminately, and often call culpable ignorance vincible, and call inculpable ignorance invincible.

1. Speculatively one can still distinguish absolutely invincible ignorance, if it can in no way be removed; morally invincible and absolutely vincible ignorance, if absolutely it can be removed but only with toil and difficulty (because there is not given a proximate moral power for overcoming it); and morally vincible ignorance, if it can be removed morally and by ordinary diligence. But moralists do not treat of these.

Invincible ignorance can arise from a twofold head: either because someone has not thought at all about the truth to be sought or about the danger of error (for the first idea is not in man's power), or because, if he has thought and employed diligence, nevertheless he has not arrived at the truth. Whence it is not voluntary.

On the contrary, vincible ignorance is voluntary, whether directly and in itself, as if someone wills to be ignorant; or only indirectly from negligence, as if he omits to inquire when he ought to inquire; or only in the cause, if he wills something upon which ignorance follows (for example, drunkenness). But there are many degrees in it, which are usually reduced to three: a) ignorance strictly or simply vincible, when diligence is employed to overcome it, but not sufficient diligence, or not the whole diligence which is morally possible, or not all that which the quality of the business and person demands: it is indirectly voluntary; b) crass ignorance, when no or scarcely any diligence has been employed for acquiring knowledge, and supine ignorance, if this was so for driving away ignorance: it is voluntary, either indirectly, or in the cause; c) affected, malicious, or directly willed ignorance, when someone expressly and deliberately wills to be ignorant for any end whatever: whether so that he may act at pleasure and not be drawn back from his purpose, or so that he may have an excuse in sins committed or to be committed, or because of disgust, etc., especially if he studiously wills not to know so that he may not be drawn back from sinning but may sin more freely.

2. Several modern authors regard that three-membered distinction as not correct, because it is made with respect to a twofold diverse terminus: for ignorance is antecedent or consequent relative to the will itself of being ignorant; but it is antecedent or concomitant relative to the will of the work to be known. Nevertheless it seems that it can be rightly understood and defended by saying that the three aforesaid ignorances are distinguished by reason of both termini at once, namely, by considering at once the act of the will concerning ignorance and the act of the will concerning the work.

3. By reason of the act of the will together with the work, ignorance is:

a) Antecedent, which does not follow from the will but precedes its act, and yet is the cause to it of willing and doing what it would not will nor do if knowledge were present (according to the present disposition). Hence ignorance is the cause of the work because it removes knowledge which would impede the work, for example if someone, thinking he is killing a beast, kills a friend whom he would not have killed if he had known: such a person acts from involuntary ignorance. For all antecedent ignorance is invincible, but not conversely, because invincible ignorance is not always the reason for doing that which otherwise would not be done.

b) Concomitant, which precedes the act of the will and is joined to it, yet not as the cause of willing and doing that which is done, because even if it were not present, nevertheless the thing would be done (according to the present disposition), for example if someone, thinking he is killing a beast, kills an enemy whom he would also have killed if he had known: such a person acts with involuntary ignorance. It is also invincible.

c) Consequent, which in some way follows from an act of the will directly not willing or indirectly neglecting to inquire, and is directly or indirectly voluntary and at the same time precedes the work so that it can be the cause of willing and doing it, for example if someone voluntarily neglects to inquire about the danger of killing a man, whom, if he knew, he would not kill, or about a day of abstinence, although, if he knew that abstinence was required, he would abstain; such a person acts from voluntary ignorance. Consequent ignorance is vincible, as voluntary, whether it is vincible at the moment when the work is placed, or was formerly vincible, provided that the work was foreseen and because of it ignorance ought to have been guarded against. Otherwise it would be invincible with respect to the work, although vincible in itself, and therefore antecedent or concomitant with respect to the work which is placed.

82. Principles. I. Antecedent ignorance removes the voluntary according to that which is unknown, because it is invincible; indeed it renders the work positively involuntary simply, because it makes something against the habitual inclination of the will: for the work would not be done if ignorance were absent.

Hence: that which is done from involuntary antecedent ignorance is positively and simply involuntary; therefore such ignorance excuses.

We said: according to that which is unknown, for under another respect it can be voluntary: thus he who kills a man or a friend, thinking him to be a beast or an enemy, voluntarily shoots the arrow, but does not shoot it into a man or into a friend; and he who sins with a woman, not knowing that she is joined in marriage, although he is not guilty of adultery, nevertheless is guilty of fornication.

II. Concomitant ignorance removes the voluntary because it is invincible, but does not render the work positively involuntary, because this is not against the inclination of the will but would also be done if ignorance were not present; therefore it makes the non-voluntary. Hence: that which is done with involuntary concomitant ignorance is non-voluntary; and of this ignorance it is said: it does not accuse, nor does it altogether excuse, namely, from the habitual disposition of the will.

III. Consequent ignorance does not make the simply involuntary, but renders the work simply voluntary, because it itself is vincible and voluntary. Yet it generally (even if it is affected) makes the involuntary in a certain respect, because it is against some inclination of the will, insofar as it is the cause of doing that which would not be done if knowledge were present; hence it diminishes the voluntary and the sin according to the degree of vincibility, so that sometimes it even makes a mortal sin venial.

But it must be well noted: ignorance exceptionally in no way diminishes the voluntary, namely, if it is so affected that someone precisely chooses it in order to sin more freely or so as not to be drawn back from sin. Namely, this in no way makes the involuntary, nor therefore diminishes the voluntary and sin, but rather increases it, not by reason of itself but by reason of the cause, because there is a greater affection toward evil. For then it comes from a greater intensity or more intense inclination of the will toward sinning that someone wills to undergo ignorance.

Hence: that which is done from voluntary or consequent ignorance is simply voluntary, but ordinarily involuntary in a certain respect, and then less voluntary. This ignorance does not excuse, but accuses.

83. Observations. - 1. The general doctrine concerning ignorance is briefly expressed in canon 2202, § 1: "The violation of an unknown law is in no way imputed, if the ignorance was inculpable; otherwise imputability is diminished more or less according to the culpability of the ignorance itself."

2. The things which we have said about ignorance can be applied to inadvertence and forgetfulness, and to error. Error includes ignorance; full inadvertence and perfect forgetfulness are equated with invincible ignorance; but if they are not perfect, but arise from negligence, they are equated with vincible ignorance. Whence canon 2202, § 3: "The things which are established concerning ignorance also hold for inadvertence and error."