St. Thomas Aquinas:
Quaestiones disputatae de veritate, q. 14 ("On faith")

Article 1: What is it to believe?

Now it is claimed by Augustine in On the Predestination of the Saints [chap. 2], and it is maintained in the Gloss on the passage "Not that we are sufficient to think" (2 Cor 3:5), that to believe is to cogitate with assent.


1. One who knows is distinct from one who believes, as is evident from Augustine in On Seeing God [letter 147, chaps. 2 and 3]. But one who knows, insofar as he knows, cogitates about something and assents to it. Therefore, believing is inappropriately described when one claims that to believe is to cogitate with assent.

2. Further, cogitating conveys a sort of investigation. For to cogitate is, as it were, to 'agitate [the mind] with', i.e., to reason discursively and to compare one thing with another. But investigation is ruled out by the nature of faith. For as Damascene says [in On the Orthodox Faith II, chap. 2], faith is not an examined consent. Therefore, it is incorrect to say that to believe is to cogitate with assent.

3. Further, to believe is an act of the intellect. But to assent seems to pertain to desiring; for we are said to consent to something by means of desire. Therefore, assent does not pertain to believing.

4. Further, no one is said to be cogitating unless he is actually considering something, as is evident from Augustine, On the Trinity [chap. 7]. But one is said to believe even if he is not actually cogitating about anything--e.g., a believer who is sleeping. Therefore, to believe is not to cogitate.

5. Further, a simple light is a principle of a simple cognition. But faith is a sort of simple light, as is evident from Dionysius in On the Divine Names, chap. 7. Therefore, the believing that arises from faith is a simple cognition, and so it is not the sort of cogitation which bespeaks a comparing cognition.

6. Further, faith as it is commonly spoken of assents to a first truth because of that truth itself. But one who assents to something by means of a comparison assents to it not because of itself but because of something else to which he compares it. Therefore, in believing there is no comparing and hence no cogitating.

7. Further, faith is called more certain than every science and every cognition. But because of their certitude principles are cognized in the absence of cogitating and comparing. Therefore, believing occurs in the absence of cogitating.

8. Further, a spiritual power is more efficacious than a corporeal power; therefore, a spiritual light is more powerful than a corporeal light. But an external corporeal light perfects the eye so that it immediately cognizes visible bodies when its innate light was not sufficient for this. Therefore, it is in the absence of any cogitating or comparing that the spiritual light which comes from God will perfect the intellect so that it cognizes even those things for which natural reason is not sufficient. And so believing occurs in the absence of cogitating.

9. Further, philosophers locate the cogitative power in the sentient part [of the soul]. But to believe belongs only to the mind, as Augustine says. Therefore, to believe is not to cogitate.


One should reply that Augustine adequately describes believing. For the essence of believing, along with its differences from all the other acts of the intellect, can be demonstrated through this sort of definition of it. This is evident as follows:

I. According to the Philosopher [Aristotle] in On the Soul [III, 5], there are two operations of our intellect. The first is an operation by which the intellect formulates the simple quiddities of things, e.g., what it is to be a human being or what it is to be an animal. Now neither the true nor the false per se are found in this operation, just as they are not found in noncomplex spoken words. The second operation of the intellect is that in accord with which it composes and divides by affirming and denying. And it is in this operation that the true and the false are found, just as they are also found in a spoken complex, which is a sign of this operation.

Now believing is found not in the first operation but rather in the second. For we believe things that are true and disbelieve things that are false. This is why among the Arabs the first operation of the intellect is called imagination, whereas the second is called faith, as is evident from the words of the Commentator [Averroes] in On the Soul III, [comment 21].

II. Now since the possible intellect is, taken by itself, in potency with respect to all intelligible forms--in just the way that primary matter is in potency with respect to all sensible forms--it is also, taken by itself, no more determined to adhering to a composition than to adhering to [the corresponding] division, or vice versa.

However, anything that is determined to two things is such that it is determined to one of the two only through something that moves it. But the possible intellect is moved by only two things, viz., (i) by its proper object, which is an intelligible form, viz., what a thing is, as is claimed in On the Soul III, and (ii) by the will, which moves all the other powers, as Anselm says [in On Similitudes, chap. 2].

So it follows that our possible intellect is related in diverse ways to the parts of a contradiction.

    A. For sometimes it is not inclined more to the one part than to the other. This is either (i) because of an absence of things that move it, as in the case of those problematic matters concerning which we have no arguments [one way or the other], or (ii) because of an apparent equality of the things that move it to the one part and the other. And this is the condition of one who is in doubt [dubitare], i.e., one who fluctuates between the two parts of the contradiction.

    B. On the other hand, it is sometimes the case that (i) the intellect is inclined more to one part than to the other, but that (ii) that which inclines the intellect does not move it sufficiently to determine it totally to the one part. Thus the intellect accepts the one part and yet is always in doubt with respect to the opposite part. And this is the condition of one who opines [opinari], i.e., one who accepts the one part of the contradiction with a wariness about the other.

    C. Now sometimes the possible intellect is determined in such a way that it adheres totally to one part. But it is determined in this way sometimes by the intelligible object and sometimes by the will.

      i. It is determined in this way by the intelligible object sometimes mediately and sometimes immediately.

      It is determined immediately when the truth of intelligible propositions is infallibly apparent at once on the basis of the intelligible things themselves. This is the condition of one who understands principles (intelligere), which are immediately known once their terms are grasped, as the Philosopher says [in Posterior Analytics I]. And so just on the basis of what a thing is the intellect is immediately determined to propositions of this sort.

      On the other hand, it is determined mediately when, after the definitions of the terms have been grasped, the intellect is determined to one part of a contradiction by the power of the first principles. And this is the condition of one who knows [scientifically] (scire).

      ii. But sometimes the intellect cannot be determined to one part of a contradiction either immediately through the definitions of the terms, as in the case of principles, or [mediately] by the power of the first principles, as in the case of demonstrated conclusions. Instead, it is determined by the will, which chooses to assent determinately and precisely to one part because of something that is sufficient to move the will but not sufficient to move the intellect--and this because it seems good or fitting to assent to that part. And this is the condition of the one who believes, as when one believes what a man says because it seems proper or beneficial to do so.

      And it is also in this way that we are moved to believe what someone says because the reward of eternal life is promised to us if we believe; and the will is moved by this reward to assent to the things that are said, even though the intellect is not moved by what is understood. And this is why Augustine, [in Commentary on John, chap. 26, "No one can come ..."], says that an unwilling man is capable of other things, but only a willing man is capable of believing.

III. From what has been said it is evident that assent is not found in the operation of the intellect by which it formulates the simple quiddities of things, since there is no truth or falsity there. For we are said to assent to something only when we cleave to it as true. Similarly, one who is in doubt does not have assent, since he does not cleave to the one part more than to the other. Similarly, one who opines does not have assent, since his acceptance is not fixed firmly with respect to one of the two parts. Rather, as Isaac and Avicenna claim, a fixed judgment (sententia) is a distinct or absolutely certain conception of one of the two parts of a contradiction; but 'to assent' (assentire) is taken from sententia. Now one who understands (intelligere) does have assent, since he cleaves with absolute certainty to one part; however, he does not have cogitation, since he is determined to one of the two parts in the absence of any comparison. On the other hand, one who knows (scire) has both cogitation and assent; however, the cogitation causes the assent and the assent terminates the cogitation. For on the basis of the very comparison of the principles with the conclusions he assents to the conclusions by tracing them back to the principles, and there the movement of the one who is cogitating is fixed and put to rest. For in knowledge (scientia) the motion of reason begins from an understanding (intellectus) of the principles and is terminated in that same understanding by means of a tracing back. And so the person in question does not have the assent and the cogitation on equal footing, as it were; instead, the cogitation leads to the assent, and the assent puts the cogitation to rest.

But in faith the assent and the cogitation are, as it were, on equal footing. For the assent is caused not by the cogitation but, as was said above, by the will. But because the intellect is not at all terminated in one part in such a way that it is brought to its proper terminus, which is the vision of something intelligible, it follows that its motion has not yet been put to rest. Instead, it still has cogitation and investigation concerning those things which it believes, even though it assents to them with absolute firmness. For just taken by itself, the intellect is not satisfied and it is not terminated in one part; rather, it is terminated only from the outside. And this is why the intellect of one who believes is said to be captivated. For it is being held fast by something else's terminus and not by its own proper terminus (2 Cor 10:5, "... bringing the intellect into captivity"). This is also why it is the case that in one who believes, though not in one who understands or knows, there can arise a movement with respect to the contrary of that which he holds with absolute firmness.

So, then, it is through assent that believing is separated off (i) from the operation by which the intellect sees simple forms, i.e., quiddities and (ii) from doubt (dubitatio) and (iii) from opinion (opinio); on the other hand, it is through cogitation that it is separated off from understanding (intellectus), whereas it is separated off from knowledge (scientia) by the fact that it has cogitation and assent on an equal footing, as it were.


AD 1. The reply to the first objection is evident from this.

AD 2. To the second objection one should reply that the reason why faith is not called an examined consent is that the assent (or consent) of faith is not caused by an investigation on the part of reason. However, this does not rule out its being the case that in the intellect of one who believes there remains some cogitation or investigation concerning the things which he believes.

AD 3. To the third objection one should reply that the will, though not the intellect, is referred back to a preceding power, viz., to the intellect. And the reason why assent properly pertains to the intellect is that it conveys a certain absolute adherence to that to which one assents. On the other hand, consent properly belongs to the will, since to consent is to 'think together with another', and so consent is said to be ordered to or compared with something that precedes it.

AD 4. To the fourth objection one should reply that because (i) habits are cognized through acts and because (ii) habits themselves are the principles of acts, habits are sometimes denominated by the names of their acts. And so the names of the acts are sometimes taken as proper names, as it were, for the acts themselves, and they are sometimes taken as names for the habits. So 'believing', insofar as it conveys the act of faith, always includes actual considering, but this is not the case insofar as 'believing' is taken for the habit. So one who is sleeping is said believe insofar as he has the habit of faith.

AD 5. To the fifth objection one should reply that faith includes something of perfection and something of imperfection. The firmness itself which pertains to assent bespeaks perfection, whereas what bespeaks imperfection is the lack of vision in virtue of which a movement of cogitation still remains in the mind of the one who believes. Therefore, that which bespeaks perfection, viz., assenting, is caused by the simple light, which is faith; but to the extent that that light is not perfectly participated in, the imperfection of the intellect is not totally removed, and so the movement of cogitation remains in the intellect without being put to rest.

AD 6. To the sixth objection one should reply that this argument proves or establishes that cogitation* is not a cause of the assent of faith, but it does not prove that cogitation* does not accompany the assent of faith.

AD 7. To the seventh objection one should reply that 'certitude' can convey two things. One is a firmness of adherence, and in this sense faith is more certain than any understanding or knowledge, since the first truth, which causes the assent of faith, is a more powerful cause than is the light of reason, which causes the assent of understanding and of knowledge. But 'certitude' also conveys the evidentness of that to which one assents, and faith does not have certitude in this sense, whereas understanding and knowledge do. And this is why understanding does not involve cogitation.

AD 8. To the eighth objection one should reply that the argument would go through straightforwardly if we participated perfectly in the spiritual light in question--which will happen in heaven, where we will see perfectly those things which we now believe. But the fact that the things which that light perfects us to know do not appear manifestly [in our present state] derives from our defective participation in that light and not from the efficacy of the spiritual light itself.

AD 9. To the ninth objection one should reply that the cogitative power is that which is the highest in the sentient part [of the soul], where the sentient part attains to the intellective part in a certain way, so that it participates in that which is lowest in the intellective part, viz., discursive reasoning--and this according to the rule of Dionysius in On the Divine Names, chap. 2, that the beginnings of the secondary things are conjoined to the ends of the primary things. Thus this cogitative power is called particular reason, as is evident from the Commentator in On the Soul III, [comment 58]. But this is the case only in human beings. In brute animals natural judgment takes the place [of particular reason]. And so universal reason itself, which is in the intellective part of the soul, is called cogitation because of a similarity in these operations.

Translated by
Alfred J. Freddoso
University of Notre Dame