Summa Theologiae Moralis, vol. I: De Principiis

S. Th. II-II, q. 1, a. 3, 4, 5 ; I-II, q. 67, a. 3 and 5 ; De Verit., q. 14, a. 9.

677. Two conditions are required for the object of faith. — For something to be capable of being believed, it is required that it be at once true and obscure or non-evident. Hence theologians say that there are two material conditions of the object of faith, namely, that it be true and obscure, and two proper states of faith on the part of the object : infallibility and obscurity.

678. The infallibility of faith. — First it is required that the material object of faith be true (Num. XXIII, 19 ; Heb. VI, 18) : faith cannot be of what is false, since, as the Vatican Council defines (sess. 3, c. 4), the assent of faith is not « a vain motion of the mind, but a firm and certain assent of the intellect », given to revealed truth « on account of the authority of God, who can neither deceive nor be deceived ».

a) Not on the part of God revealing, because He cannot say what is false : for if God, by Himself or through another, could say what is false, this would happen either because He did not know the truth, or because, knowing it, He was unwilling to declare it, or because He could not, through the fault of His nature, declare it. But all of this is impossible to God, since He is infinitely wise, infinitely good, and infinitely powerful.

b) Nor on the part of the man believing : for nothing is attained and believed by the habit of faith except on account of the authority and testimony of God, who is Himself the first truth. Therefore if faith were of something false, it would not be of it on account of God's authority, and so the principal and proper motive of faith would be lacking, and faith would not be a virtue.

Faith is an intellectual virtue which does not deal with what is false, which is an evil of the intellect : for no one makes bad use of a virtue. Hence if someone were to assent to what is false, which through even invincible ignorance he thinks to have been revealed by God, such a person does not assent out of the supernatural habit of theological faith on account of God's authority, because God revealed it, but only by a natural act on account of error, because he falsely thinks God revealed it. Nor does God, by grace, concur with such an act, by which the intellect adheres to what is false. Hence faith is infallible.

679. The obscurity of faith. — Secondly, it is required that the material object of faith be obscure or non-evident : for faith is « the argument of things not seen », Heb. XI, 1. Unde, nisi obiectum materiale sit obscurum seu non evidenter cognitum, proprie non est fides. — Hinc formaliter distinguitur fides a scientia et ab intellectu evidenti.

a) All theologians unanimously admit that the material object of faith is formally non-evident, by reason of the motive, inasmuch as it is attained through the authority of God who is not seen. This is necessary, otherwise the assent would not be properly by faith but would be the assent of science or of evident cognition.

b) All likewise hold that something cannot be believed and at the same time seen with the beatific vision, according to 1 Cor. XIII, 9-10.

c) They likewise grant that those things of which faith is principally about are altogether obscure and not evident : for the beatific vision and other mysteries are not seen in themselves by the intellect of the wayfarer, but only darkly and as in a mirror (1 Cor. XIII, 12).

d) They dispute whether other objects which can be known naturally, but which nevertheless are revealed, can be believed by those who also have an evident rational cognition of these objects, e.g. whether he who has full evidence of the existence of God, or of creation, or of providence, etc., can still admit these on account of the authority of God who has revealed even these.

680. How evidence impedes faith. — In this question :

1° It is certain that he who has evidence of some thing this can believe it implicitly, inasmuch as he ought to believe in a general way everything which God has revealed and cannot exclude any of it, and this is the meaning of the Vat. Council, sess. 3, c. 3.

2° Indeed explicitly but at another moment than he has the evident cognition : for he who, e.g., now demonstrates the existence of God, can at another time admit it by faith, namely, when he is not actually considering the demonstration. For then, although no doubt can occur concerning the existence of God, since the evidence can be produced, nevertheless, before that evidence is actually produced, the assent is not the assent of science but of faith.

3° Hence in the same man, concerning the same truth, there can be at the same time the habit of faith and the act of science, the act of faith and the habit of science, indeed even the habit of faith and the habit of science, by which at the same time he is disposed for believing and for knowing, not simultaneously but at different times.

4° For it seems to be said with S. Thomas¹], that at the same moment in which one makes an evident demonstration of some truth, or most fully remembers a prior demonstration, so that one has plain evidence of the truth, one cannot at this moment accept the same truth on account of divine testimony. — It is proved :

a) Internal experience shows that we never admit, nor can admit, what we see with our eyes on the testimony of another, even one most worthy of faith ; likewise it is clear that no one believes, nor can believe, the first principles, e.g. the principle of contradiction, which are seen with the mind ; whence in heaven faith is brought to nothing when God's vision comes ; the same seems to be said of that moment in which someone, having made the demonstration, sees with the mind the conclusion with evidence of the existence of God or of another natural truth : for immediate and mediated evidence are of the same kind. The law of our intellect, namely, is that we cannot believe what we see.

b) By reason : The intellect cannot at the same moment perfectly rest in the truth and at the same time not rest. But he who has altogether evident cognition, rests perfectly in the truth and indeed necessarily ; he who believes does not rest in it, for there remains for him the possibility and freedom of doubting or of not assenting. Therefore at the same moment one cannot hold the same truth by faith and by evidence²],

c) By a reply to the chief argument of the adversaries : The same truth can at the same time be admitted on account of a twofold motive : namely, evidence and authority. For it is easy to distinguish : if those motives do not require a contrary disposition of the intellect, I grant ; if they require a contrary disposition, I deny. For otherwise in the same way would be demonstrated the possibility of faith in heaven, or the compatibility of science and opinion.

681. Observation. — From this it does not follow that the merit of faith is diminished, if someone does not believe revealed rational truths of which he has evidence. For, as S. Thomas notes, q. 2, a. 10, ad 2 : « The demonstrative reasons brought forward for those things which are preambles to faith (but not for the articles), although they diminish the formal notion of faith, because they make what is proposed appear evident, do not however diminish the formal notion of charity, by which the will is prompt to believe them, even if they do not appear, and therefore the notion of merit is not diminished ».