Article I: On Ignorance as a Cause of Sin on the Part of Reason — On Sins of Ignorance

St. Thomas, I-II, q. 76; De Malo q. 3, a. 6, 7, 8.

464. On the part of reason, the cause of sin is ignorance and inconsideration of the intellect, not any whatever, but that which removes knowledge (whether universal knowledge of right, or particular knowledge of fact or circumstance) by which, if it were present or present more fully, sin would not occur. Whence it is not the cause of sin per se, but per accidens, insofar as it removes that which would impede sin. But if someone is so disposed that without ignorance he would nevertheless sin, ignorance would not be the cause of sin: such a one does not sin from ignorance or on account of ignorance, but sins with ignorance or while ignorant. Thus if ignorance is concomitant, or even if it is affected but precisely for sinning more freely.

For every sin, even one done from malice, ignorance or error is required in the ultimate practical judgment, by which reason erroneously judges such an illicit act to be good for itself here and now; but sins of ignorance are called those which proceed also from a culpably erroneous speculative judgment.

1. It is called ignorance of bad election. Cf. Ethics III, lect. 3; I-II, q. 6, a. 8; II Sent. d. 39, q. 1, a. 1, ad 4.

2. "Ignorance sometimes excludes the knowledge by which someone simply knows that this which is done is evil, and then he is said to sin from ignorance; sometimes it excludes the knowledge by which man knows that this now is evil, as when one sins from passion; sometimes it excludes the knowledge by which someone knows that this evil is not to be sustained on account of the attainment of that good, although he simply knows that this is evil, and thus he who sins from malice is said to be ignorant." I-II, q. 78, a. 1, ad 1. Cf. De Malo q. 2, a. 3, ad 9.

465. Ignorance can be sin (the contrary was condemned in Coelestius and Abelard), not indeed according to itself, for it is an intellectual evil, not a moral one, but by reason of preceding negligence in learning or actual negligence in considering (Luke XII, 48; I Tim. I, 13). Nevertheless not every ignorance is sin: for invincible ignorance, which someone could not repel, is not sin, as is clear from propositions 68 of Baius and 2 of Alexander VIII, condemned; but vincible ignorance is only sin if it concerns those things which someone is bound to know, or which are necessary for directing his own acts and without which he cannot rightly exercise the due act.

1. "Negative infidelity is sin." "Invincible ignorance of the right of nature in the state of fallen nature does not excuse from formal sin."

Whence for sin it does not suffice that ignorance be voluntary, but in addition it must be culpable. For this three things are required: in order that it be voluntary, 1) that someone could have removed it, that is, had the means for that, and 2) that he adverted to it in some way; but in order that it be culpable, in addition 3) that someone was obligated to impede the ignorance, that is, to apply means lest ignorance follow. Thus ignorance of medical science is not culpable for a farmer and advocate, but for a physician.

Moreover all are bound to know a) the articles or fundamental truths of faith, b) the universal precepts of right, namely, of the Decalogue and of the Church; c) but individuals are bound to know those things which regard their state or office, at least those things which are common and occur often.

Indeed ignorance can be a special sin. Vincible ignorance 1) of a thing which we are bound to know habitually or by reason of itself (ignorance of right) is a special sin of omission, diverse from the sins which follow from it, because ignorance itself is morally evil in itself, and because one sinning thus violates two diverse precepts.

Thus, for example, if someone voluntarily were ignorant of the Incarnation or the malice of adultery or the five precepts of the Church, and therefore blasphemed Christ, or committed adultery, or ate meats, he would be guilty of a double sin.

On the contrary, 2) ignorance of a thing which someone is bound to know, not indeed permanently and by reason of itself, but transiently and on account of the work here and now to be placed (ignorance of a particular fact, for example, of a circumstance of the act), is not a sin distinct from the sin which follows from it or to which it exposes, because it is not evil except by reason of the evil effect, and therefore one sinning does not act except against one precept and one virtue.

Thus negligence of inquiring whether the present day is a day of fast (even if it were not a day of fast), because from the same precept one is bound to fast and to inquire.

466. Principles. I. Invincible and antecedent ignorance per se totally excuses from the whole sin the work which is done from it, because it renders it involuntary (Gen. IX, 21); per accidens it does not entirely excuse if it is not total but partial, because only the circumstance is unknown which, if known, would prevent the sin, and nevertheless the sin is done knowingly, for example, the killing of a man by one who does not know that he is his father (Gen. XXXVIII). Whence it excuses insofar as it is ignorance.

II. Invincible and concomitant ignorance does not entirely excuse: it excuses from sin the external work which is done with it, because it renders that work non-voluntary; but it does not totally excuse the one operating, because it does not take away every will of sinning or internal affection toward sin, since the work would nevertheless be done if ignorance were not given, for example, one who kills an enemy, thinking him to be a beast, when nevertheless he would kill if he knew. Such ignorance neither excuses entirely, nor accuses.

III. Vincible and consequent ignorance concerning these things which someone is bound to know, if it is the cause of sin which otherwise would not occur, does not totally excuse from sin the work which is done from it, because it remains voluntary (since the ignorance itself is voluntary), but it diminishes it because it renders it involuntary in a certain respect. Whence it accuses, as voluntary, and does not excuse from the whole but from so much, for example, wounding from drunkenness.

IV. Vincible but affected ignorance, and excited precisely for sinning more freely, in no way excuses from sin but rather increases it, because it proceeds from a greater will of sinning. Whence it simply accuses.