Article V: On the Definition of Sin

St. Thomas, I-II, q. 71, a. 6.

428. Sin theologically taken is defined by Augustine, book 22, Against Faustus, chapter 27: A saying, deed, or desire against the eternal law.

a) That which is material in sin is indicated, namely, the act, which is distinguished as threefold to denote the threefold sin which can be committed by thought, word, and deed. But since affirmation and negation are reduced to the same genus, under the name of saying, deed, or desire (that is, willed or loved thing) there also comes the sin of omission: not-said, not-done, not-desired, when someone ought to say, do, or will. Besides, the sin of omission radically consists in a positive act, because it is not voluntary unless it is derived from deliberation by which man has decreed either to omit the precept or to do something incompossible with it.

b) It is said: against law, so that it may be implicitly signified that for sin it is required that it be voluntary and free: for no one properly and formally acts against law except through a voluntary and free act, or unless he freely wills to transgress it.

c) It is said: against the eternal law, because the eternal law is the first and essential rule of human acts, ordering them to the end, from which they have that they are good or evil; and although sins are also against reason, or also sometimes against human laws, nevertheless these are not sins except because they are at the same time against the eternal law of God, from which all laws are derived and which prescribes that they be obeyed. This is the formal of sin, that it is against the law of God.

429. Sin strictly so called is also rightly defined philosophically: An act against right reason, or a human act discordant with rational nature.

Thus according to what St. Thomas observes, ad 5, "by theologians sin is considered chiefly insofar as it is an offense against God, but by the moral philosopher insofar as it is contrary to reason." Nevertheless there is no philosophical sin, that is, one repugnant to right reason, which is not at the same time theological, or contrary to the eternal law, because on the one hand whatever is against right reason is against the eternal law, which is the reason of God, since right reason is nothing other than a participation of the eternal law in a created mind; on the other hand it is impossible that any man who has sufficient use of reason invincibly be ignorant of God and the eternal law. Although, therefore, the concept of philosophical sin is not metaphysically repugnant, for an act sufficiently appears evil and sin from the fact that it is repugnant to the rule of reason alone, abstracting (not excluding) from the eternal law, nevertheless in fact, in the real order, it does not exist, as is clear from proposition 2 condemned as scandalous, rash, and erroneous by Alexander VIII.

1. "Philosophical or moral sin is a human act discordant with rational nature and right reason; but theological and mortal sin is a free transgression of the divine law. Philosophical sin, however grave, in him who either is ignorant of God or does not actually think of God, is grave sin, but it is not an offense of God, nor mortal sin dissolving friendship with God, nor worthy of eternal punishment." Lehu notes: "In the proposition the two indicated cases are condemned, not however copulatively but disjunctively: in him who either is ignorant of God, or does not actually think of God. Therefore in each case taken separately the proposition is equally condemned," op. cit., n. 217.

430. Sin is less well defined by some as: A free transgression of the law of God, or a voluntary recession from the divine rule.

This definition, although true, is nevertheless incomplete because it is made according to the formal element and does not indicate that the material element is of the essence of sin; it is also less proper than the definition of Augustine: for sin is more a voluntary act than a privation or recession, because the will does not directly tend into privation, but into a positive good which has privation annexed: for good is its proper object. Whence the positive element must be placed first and directly.

1. St. Thomas, II Sent. d. 35, q. 1, a. 2.

431. Observation. - Just as the notion of sin, so the definition does not belong perfectly except to actual mortal sin; imperfectly and in a certain respect, to others.