Article II. On Ignorance

I. Notion. Ignorance is the habitual lack of knowledge. It differs, therefore, from inadvertence, which is the actual lack of knowledge in one who habitually knows the matter.

II. Division. Ignorance is divided:

1. By reason of the subject, into negative, privative, and positive ignorance. Negative ignorance is ignorance in a subject not capable of knowledge, as in an infant or in a madman; it is usually called nescience. Privative ignorance is ignorance in a subject capable of knowledge. Positive ignorance is ignorance joined with error or the admission of the false; it is called simply error (St. Alphonsus, Homo Apostolicus, tract 3, n. 13; cf. St. Thomas, I-II, q. 76, a. 2; De Malo, q. 3, a. 1).¹

2. By reason of the object, into ignorance of law and ignorance of fact. The former is that by which either the existence, or the meaning, or the extension, or the cessation of the law is unknown. The latter is that by which a fact or some circumstance is unknown, on which the application of the law depends. If someone does not know that the fast before Holy Communion is to be observed from the twelfth hour, there is ignorance of law. If someone does not know that he has eaten after the twelfth hour, there is ignorance of fact (St. Alphonsus, same place).

3. By reason of influence on the act, into antecedent and concomitant ignorance. Antecedent ignorance is that which is the cause of the act, so that the act would not have been placed if the ignorance had not existed, as if you kill a man thinking he is a wild beast. Concomitant ignorance is said to be that which accompanies the act but is not its cause, so that, even if it had been absent, the act would nevertheless have been placed, as if, prepared to kill an enemy, you kill him thinking he is a wild beast (St. Thomas, I-II, q. 6, a. 8; St. Alphonsus, same place).

4. By reason of perfection, into full and half-full ignorance, according as the truth, for example the malice of the act, is not at all adverted to or is adverted to in some measure, as if someone doubts whether some act is evil, or whether from some action an evil effect is going to follow.

5. By reason of the power to dispel it, into invincible and vincible ignorance, according as it cannot or can be overcome by moral diligence. Invincible ignorance is, for example, the ignorance of one who does not even think about some matter, say, about the malice of an act.

6. By reason of fault, into inculpable and culpable ignorance, according as it ought not to have been dispelled, or ought to have been dispelled and was not dispelled. Thus, for example, one who does not know the duties of his state and does not learn them labors under culpable ignorance.

Culpable ignorance is distinguished into affected and non-affected. Affected ignorance is had if the truth is not sought precisely so that one may sin more freely. Otherwise it is non-affected. This latter is divided into crass or supine, simply grave, and light ignorance, according as one was wholly, or almost wholly, gravely, or lightly negligent in seeking the truth which ought to have been sought.

¹ Others do not call the ignorance which we have called negative ignorance properly so called, but nescience; and they distinguish ignorance properly so called into negative and privative, according as it is ignorance of knowledge not owed, as jurisprudence in a farmer, or of knowledge owed, as the Decalogue in a Christian.

III. Influence on the voluntary-free.

1. Full ignorance removes the voluntary-free character of a work placed from it or with it, and excuses from fault. For ignorance of this kind excludes all cognition. Now what is entirely unknown cannot be willed, according to the saying: nothing is willed unless known. Add the second proposition condemned by Alexander VIII: "Even if invincible ignorance of the natural law is granted, in the state of fallen nature this does not excuse the one acting from formal sin."¹

2. Half-full ignorance operates thus:

a) If the truth can be sought, and is not sought at all or not sufficiently sought, it does not remove the voluntary-free character of the work placed from it or with it, nor does it excuse from fault. For one who acts thus admits the work, whatever it may be, and rashly exposes himself to the danger of doing what is forbidden. Nevertheless, the aforesaid ignorance generally lessens the voluntary and the fault, since the cognition is less perfect. I said generally, because with respect to affected ignorance it is disputed whether it increases or lessens the voluntary. St. Thomas teaches: "Such ignorance seems to increase the voluntary and the sin" (I-II, q. 76, a. 4). Yet it does not seem to increase it by reason of itself or as such, since it involves a more imperfect knowledge; rather, it points to a greater inclination toward the evil act, and under this respect a greater sin.

b) If the truth cannot be sought, or has been sufficiently but fruitlessly sought, it removes the voluntary-free character and excuses from fault, according as the ignorance or doubt concerning the lawfulness of the work has been practically set aside, or has not been set aside, by the aid of a reflex principle; as will be explained more fully in the treatise on conscience. There we shall likewise say how great a diligence must be used in seeking the truth.

Note 1. Under the name of ignorance, forgetfulness is also understood; likewise inadvertence, which is actual ignorance in one who enjoys habitual knowledge.

Note 2. A sin committed with half-full ignorance and with the truth not sufficiently investigated is of the same species as a sin knowingly committed in the same matter.

¹ Denzinger-Bannwart, number 1292.