Even King David, after beholding "the moon and the stars," humbly asks their Creator: "What is man that thou art mindful of him?" (Psalm 8:4-5). And even St. Thomas the Apostle ("Doubting Thomas") was the first doubting scientist:
Now Thomas, one of the twelve, who is called Didymus, was not with them when Jesus came. The other disciples therefore said to him: We have seen the Lord. But he said to them: Except I shall see in his hands the print of the nails, and put my finger into the place of the nails, and put my hand into his side, I will not believe. And after eight days again his disciples were within, and Thomas with them. Jesus cometh, the doors being shut, and stood in the midst, and said: Peace be to you. Then he saith to Thomas: Put in thy finger hither, and see my hands; and bring hither thy hand, and put it into my side; and be not faithless, but believing. Thomas answered, and said to him: My Lord, and my God. Jesus saith to him: Because thou hast seen me, Thomas, thou hast believed: blessed are they that have not seen, and have believed.
How can we make sense of this? Does it apply to understanding everything? What does St. Anselm mean when he says "faith seeking understanding" (fides quærens intellectum) and "Nor do I seek to understand that I may believe, but I believe that I may understand [credo ut intelligam]. For this too I believe, that unless I first believe, I shall not understand [«nisi credidero, non intelligam», St. Augustine Sermo 43 7,9; cf. Isaias 7:9]." (Proslogion I)? St. Augustine—the 5th century saint whose theory of time is frequently quoted in the quantum cosmology literature, e.g., in Rev. Mod. Phys. 61, 1 (1989) pg. 15—says:
7. [...]So, many modern atheist scientists are missing faith, one of the "two wings on which the human spirit rises to the contemplation of truth," which are faith and reason (Fides et Ratio 1.). As a result, doubt hinders the full contemplation of the absolute truths.
What were we arguing about? You were saying “Let me understand in order to believe”; I was saying “In order to understand, believe.” An argument has arisen, let us put it before a judge, let a prophet judge, or rather let God judge through a prophet. Let's both of us keep silent. What we have each said has been heard: “Let me understand,” you say, “in order to believe.” “Believe,” say I, “in order to understand.” Let the prophet make his reply: “Unless you believe, you shall not understand” (Is 7:9).
9. Just now when the gospel was being read, you heard If you can believe—the Lord Jesus said to the boy's father, If you can believe, all things are possible to one who believes (Mk 9:23). And the man took a look at himself, and standing in front of himself, not in a spirit of brash self-satisfaction but first examining his conscience, he saw that he did have some faith in him, and he also saw that it was tottering. He saw both things. He confessed he had one, and he begged for help for the other. I believe, Lord, he says. What was to follow, if not “Help my faith”? That's not what he said. “I believe, Lord. I can see this something in me, which I'm not lying about. I believe; I'm telling the truth. But I also see this other heaven knows what, and I don't like it. I want to stand, I'm still staggering. I'm standing and speaking, I haven't fallen, because I believe. But yet I'm still staggering: Help my unbelief” (Mk 9:24).
And so, beloved, that other man too whom I set up against myself, calling in the prophet as referee because of the argument that arose between us, he too isn't saying just nothing when he says “Let me understand, in order to believe.” Of course, what I am now saying, I am saying to help those people believe who do not yet believe. And yet, unless they understand what I am saying, they cannot believe. So what this person says is partly true—“Let me understand, in order to believe”; and I on my side, when I say, just as the prophet says, “On the contrary, believe, in order to understand,” am speaking the truth. Let's come to an agreement, then. So: understand, in order to believe; believe, in order to understand. I'll put it in a nutshell, how we can accept both without argument: Understand, in order to believe, my word; believe, in order to understand, the word of God.
Obviously, though, atheists would object to most of what has been said, e.g., the invoking of God and absolutes. They might say:
Why is any of this necessary for science, which just studies contingent—viz., non-necessary—things? It is untrue that "faith purifies reason" (fides purificat rationem) and "liberates [it] from presumption" ([fides] rationem a nimia confidentia exsolvit), no (Fides et Ratio 76.)? Faith, especially that of organized religions, has destroyed science by enslaving it to outdated, primitive presumptions, e.g., that the universe and everything in it was created in a week. [To which I would immediately respond, due to their misunderstanding: "St. Augustine, e.g., wrote that the Genesis 'day' is not necessarily 24 hours. In fact, before the earth and sun were created, how could one even define 'day' anyways?"] Modern science has enlightened us now. We no longer need blind religion or anything else besides our intellects and reason for our guide.The problem with this sort of Cartesian "Cogito, ergo sum" ("I think; therefore, I am.") is that it denies an objective reality and makes us our own authorities even on matters of which we are often unqualified to judge; this is extreme Protestantism. The atheist scientists might maintain that truth is relative but they have no way of scientifically justifying this. In a sense, what they have faith in is what is most detrimental to science: agnosticism, in the sense that the human intellect can never know anything with certainty, even the basic premises of logic such as the law of non-contradiction or the syllogism, and that which follows from it: extreme doubt, skepticism, and nihilism. Even the pagan Aristotle realized—almost á la Kurt Gödel and his Incompleteness Theorem—that, although there is scientific knowledge, not all truths are demonstrable as through a syllogism or science experiment; Aristotle was therefore one of the first anti-positivists (on positivism, cf. Card. Schönborn's "The Designs of Science"). We quote first his Posterior Analytics—a book that even Galileo faithfuflly followed despite his disagreements with Aristotle's physics—on "The erroneous views of scientific knowledge" and "The futility of circular demonstration," both of which I believe many atheist scientists are culpable, then we follow it by St. Thomas Aquinas's commentary, which more illuminates Aristotle's work in the present context of "crede, ut intelligas:"
Some hold that, owing to the necessity of knowing the primary premisses, there is no scientific knowledge. Others think there is, but that all truths are demonstrable. Neither doctrine is either true or a necessary deduction from the premisses. The first school, assuming that there is no way of knowing other than by demonstration, maintain that an infinite regress is involved, on the ground that if behind the prior stands no primary, we could not know the posterior through the prior (wherein they are right, for one cannot traverse an infinite series): if on the other hand—they say—the series terminates and there are primary premisses, yet these are unknowable because incapable of demonstration, which according to them is the only form of knowledge. And since thus one cannot know the primary premisses, knowledge of the conclusions which follow from them is not pure scientific knowledge nor properly knowing at all, but rests on the mere supposition that the premisses are true. The other party agree with them as regards knowing, holding that it is only possible by demonstration, but they see no difficulty in holding that all truths are demonstrated, on the ground that demonstration may be circular and reciprocal.
Our own doctrine is that not all knowledge is demonstrative: on the contrary, knowledge of the immediate premisses is independent of demonstration. (The necessity of this is obvious; for since we must know the prior premisses from which the demonstration is drawn, and since the regress must end in immediate truths, those truths must be indemonstrable.) Such, then, is our doctrine, and in addition we maintain that besides scientific knowledge there is its originative source which enables us to recognize the definitions.
Now demonstration must be based on premisses prior to and better known than the conclusion; and the same things cannot simultaneously be both prior and posterior to one another: so circular demonstration is clearly not possible in the unqualified sense of ‘demonstration’, but only possible if ‘demonstration’ be extended to include that other method of argument which rests on a distinction between truths prior to us and truths without qualification prior, i.e. the method by which induction produces knowledge. But if we accept this extension of its meaning, our definition of unqualified knowledge will prove faulty; for there seem to be two kinds of it. Perhaps, however, the second form of demonstration, that which proceeds from truths better known to us, is not demonstration in the unqualified sense of the term.
The advocates of circular demonstration are not only faced with the difficulty we have just stated: in addition their theory reduces to the mere statement that if a thing exists, then it does exist—an easy way of proving anything. That this is so can be clearly shown by taking three terms, for to constitute the circle it makes no difference whether many terms or few or even only two are taken. Thus by direct proof, if A is, B must be; if B is, C must be; therefore if A is, C must be. Since then—by the circular proof—if A is, B must be, and if B is, A must be, A may be substituted for C above. Then ‘if B is, A must be’=’if B is, C must be’, which above gave the conclusion ‘if A is, C must be’: but C and A have been identified. Consequently the upholders of circular demonstration are in the position of saying that if A is, A must be—a simple way of proving anything. Moreover, even such circular demonstration is impossible except in the case of attributes that imply one another, viz. ‘peculiar’ properties.
Now, it has been shown that the positing of one thing—be it one term or one premiss—never involves a necessary consequent: two premisses constitute the first and smallest foundation for drawing a conclusion at all and therefore a fortiori for the demonstrative syllogism of science. If, then, A is implied in B and C, and B and C are reciprocally implied in one another and in A, it is possible, as has been shown in my writings on the syllogism, to prove all the assumptions on which the original conclusion rested, by circular demonstration in the first figure. But it has also been shown that in the other figures either no conclusion is possible, or at least none which proves both the original premisses. Propositions the terms of which are not convertible cannot be circularly demonstrated at all, and since convertible terms occur rarely in actual demonstrations, it is clearly frivolous and impossible to say that demonstration is reciprocal and that therefore everything can be demonstrated.
Since the object of pure scientific knowledge cannot be other than it is, the truth obtained by demonstrative knowledge will be necessary. And since demonstrative knowledge is only present when we have a demonstration, it follows that demonstration is an inference from necessary premisses.
—Aristotle's Posterior Analytics bk. 1 ch. 3-4 (72b5-24)
Therefore, contrary to the atheist scientists who nihilistically think doubt is the supreme intellectual virtue—even though they are correct that humility is good, just not the sort they conceive as devaluing human life, which is really denying the reality of the sacredness of life—we can see the necessity of belief in the ultimate principles upon which science bases itself. If "faith is more certain than science and the other intellectual virtues" (Summa Theologica IIª-IIae q. 4 a. 8), then science—especially the supreme science of theology that unifies all others—is possible because "demonstration must be based on premisses prior to and better known than the conclusion," as Aristotle said above.
DISCUSSION OF TWO ERRORS—EXCLUSION OF THE FIRST ONE
b5. Some hold that, owing— b8. The first school— b15. The other party agree— b18. Our own doctrine is that
After determining about the knowledge of the principles of demonstration, the Philosopher now excludes the errors which have arisen from these determinations. Concerning this he does three things. First, he states the errors. Secondly, the reasons they erred (72b8). Thirdly, he removes the roots of these reasons (72b 18).
He says therefore first (72b5), that two contrary errors have arisen from one of the truths established above. For it has been established above that the principles of demonstration must be known and must be even better known. But the first of these is sufficient for our purpose. For some, basing themselves on this first statement, have come to believe that there is no science of anything, whereas others believe that there is science, even to the extent of believing that there is science of everything through demonstration. But neither of these positions is true and neither follows necessarily from their reasons.
Then (72b8) he presents the reasons why they have fallen into these errors. And first of all he presents the reason given by those who say that there is no science, and it is this: The principles of demonstration either proceed to infinity or there is a halt somewhere. But if there is a process to infinity, nothing in that process can be taken as being first, because one cannot exhaust an infinite series and reach what is first. Consequently, it is not possible to know what is first. (They are correct in thus arguing, for the later things cannot be known unless the prior ones are known).
On the other hand, if there is a halt in the principles, then even so, the first things are still not known, if the only way to know scientifically is through demonstration. For first things do not have prior principles through which they are demonstrated. But if the first things are not known, it follows again that the later things are not known in the strict and proper sense, but only on condition that there are principles. For it is not possible for something to be known in virtue of something not known, except on condition that that unknown be a principle. So in either case, whether the principles stop or go on to infinity, it follows that there is no science of anything.
Secondly (72b15), he presents the reasoning of those who say that there is science of everything through demonstration, because to their basic premise—the only way to know scientifically is by demonstration—they added another, namely, that one may demonstrate circularly. From these premises it followed that even if a limit is reached in the series of the principles of demonstration, the first principles are still known through demonstration, because, they said, those principles were demonstrated by previous ones. For a circular demonstration is one which is reciprocal, i.e., something which was first a principle is later a conclusion, and vice versa.
Then (72b18) he cuts away the false bases of these arguments. First, their supposition that the only way to know scientifically is by demonstration. Secondly, their statement that it is legitimate to demonstrate circularly (72b25).
He says therefore first (72b18), that not all scientific knowledge is demonstrative, i.e., obtained through demonstration, but the scientific knowledge of immediate principles is indemonstrable, i.e., not obtained by demonstration. However, it should be noted that Aristotle is here taking science in a wide sense to include any knowledge that is certain, and not in the sense in which science is set off against understanding, according to the dictum that science deals with conclusions and understanding [intuition] with principles.
But that it is necessary for some things to be held as certain without demonstration he proves in the following way: It is necessary that the prior things from which a demonstration proceeds be known in a scientific way. Furthermore, these must be ultimately reduced to something immediate; otherwise one would be forced to admit that there is an actual infinitude of middles between two extremes—in this case between the subject and predicate. Again, one would have to admit that no two extremes could be found between which there would not be an infinitude of middles. But as it is, the middles are such that it is possible to find two things which are immediate. But immediate principles, being prior, must be indemonstrable. Thus it is clear that it is necessary for some things to be scientifically known without demonstration.
Therefore, if someone were to ask how the science of immediate principles is possessed, the answer would be that not only are they known in a scientific manner, but knowledge of them is the source of a science. For one passes from the knowledge of principles to a demonstration of conclusion on which science, properly speaking, bears. But those immediate principles are not made known through an additional middle but through an understanding of their own terms. For as soon as it is known what a whole is and what a part is, it is known that every whole is greater than its part, because in such a proposition, as has been stated above, the predicate is included in the very notion of the subject. And therefore it is reasonable that the knowledge of these principles is the cause of the knowledge of conclusions, because always, that which exists in virtue of itself is the cause of that which exists in virtue of something else.
THE SECOND ERROR IS EXCLUDED BY SHOWING THAT CIRCULAR DEMONSTRATION IS NOT ACCEPTABLE
b25. Now demonstration must— b33. The advocates of circular— b38. Thus by direct proof— a1. Since then— a6. Moreover, even such
After excluding one false basis by showing that not all science depends on demonstration, the Philosopher now excludes another by showing that it is not possible to demonstrate circularly.
To understand this it should be noted that a demonstration is circular when the conclusion and one of the premises (in converted form) of a syllogism are used to prove the other premise. For example, we might form the following syllogism:
- Every rational mortal animal is risible;
- Every man is a rational mortal animal:
- Therefore, every man is risible.
Now if the conclusion were to be used as one principle and the minor in converted form as the other, we would get:
- Every man is risible;
- Every rational mortal animal is a man:
- Therefore, every rational mortal animal is risible—which was the major of the first syllogism.
Accordingly, he presents three arguments to show that it is not possible to demonstrate circularly. The first of these (72b25) is this: In a circular syllogism the same thing is at once a conclusion and a principle. But a principle of a demonstration is prior to and better known than the conclusion, as has been shown above. Therefore, it follows that a same thing is both prior to and subsequent to one same thing, and also more known and less known. But this is impossible. Therefore, it is impossible to demonstrate circularly.
But someone might say that a same thing can be both prior and subsequent, although not in the same way. For example, this might be prior in reference to us, but that prior absolutely. Thus singulars are prior in reference to us and subsequent absolutely: and conversely for universals. Again, induction makes something known in one way and demonstration in another way. For demonstration proceeds from things that are prior absolutely, but induction from things that are prior in reference to us.
Now if a circular demonstration were so constructed that something is first concluded from things that are absolutely prior, and then from things that are prior in reference to us, it would follow that our doctrine on scientific knowing was not well established. For we stated that to know scientifically is to know the cause of a thing. From this it followed that a demonstration which causes scientific knowledge must proceed from the absolutely prior. But if demonstration were at one time to proceed from the absolutely prior and at another time from things which are prior in reference to us, we would be forced to admit that scientific knowing is not confined to knowing the cause of a thing, but that there is another, namely, that form of knowing which proceeds from what is later. Therefore, one must either admit both or admit that the second form, namely, the demonstration which proceeds from what is better known to us is not a demonstration in the absolute sense.
The aforesaid also reveals why a dialectical syllogism can be circular. For it proceeds from things which are probable. But things are said to be probable if they are better known to the wise or to a great number of persons. Consequently, a dialectical syllogism proceeds from things that are better known to us. However, it happens that a same thing is better known to some and less known to others. Consequently, there is nothing to hinder a dialectical syllogism from being circular. But a demonstration is formed from things that are absolutely prior. Therefore, as we have already stated, there cannot be circular demonstration.
Then he sets forth the second argument (72b33) and it is this: If there were circular demonstration, it would follow that a same thing is demonstrated by the same thing, as if I were to say: If it is this, it is this. In this way it is easy for anyone to demonstrate everything, for anyone, wise or ignorant, will be able to do this. Accordingly, science is not acquired through demonstration. But this is against the definition of demonstration. Therefore, there cannot be circular demonstration.
He proves the truth of the first consequence in the following way: It is obvious, first of all, that with a circular demonstration the same thing is proved by a same thing, as has been stated above, i.e., if only three terms are employed; although it makes no difference whether the reflexion be made with fewer terms or more. (By reflexion he means the process whereby one goes from principle to conclusion in a demonstration, and then from conclusion to principle). In such a reflexion it makes no difference, so far as the force of the argument is concerned, whether it involves several or fewer terms or even two. For an argument has the same force if one proceeds thus: “If it is A, it is B, and if it is B, it is C, and if it is C, it is D,” and then by reflecting continues, “If it is D, it is C, and if it is C, it is B, and if it is B, it is A”; or if he proceeds by reflecting at the very start, saying: “If it is A, it is B, and if it is B, it is A.” (Although he spoke above of three terms, he restricted himself to two terms in this example, because in the deduction he is about to make he will use a third term, which is the same as the first).
Then (72b38) he gives the form of the argument in three terms, namely: “If it is A, it is B, and if it is B, it is C; therefore, if it is A, it is of necessity C.”
Then (73a1) he shows by the aforesaid form of arguing that in a circular demonstration a same thing is proved by a same thing, using only two terms. For it consists in saying, “If it is A, it is B,” and then reflecting, “If it is B, it is A”—which is a circular demonstration. Now according to the above given form it follows from these two, that “if it is A, it is A.”
That it does follow is obvious: for just as in the first deduction which involved three terms’ C followed from B, so in the reflex deduction of two terms, A followed from B. Let us suppose, then, that the A of the second deduction, i.e., the reflex, signifies the same thing that C signified in the first, i.e., in the direct deduction which was composed of three terms. Therefore, to state in the second deduction that “if it is B it is A” is to state the same thing as was stated in the first deduction, namely, that “if it is B, it is C.” But when it was stated in the first deduction that “if it is B, it is C,” it followed that “if it is A, it is C.” Therefore, in the circular deduction it follows that “if it is A, it is A,” since C is assumed to be the same as A. In this way, it will be easy to demonstrate all things, as has been said.
Then he presents the third argument (73a6) which is this: Those who suppose that everything can be known through demonstration on the ground that demonstration is circular, must grant that anything can be demonstrated by a circular demonstration and, as a consequence, grant that in a circular demonstration each of the premises can be concluded from the conclusion. However, the only cases in which this can be done are those in which mutual conversion is possible, i.e., in things that are convertible, as properties. But not all things are so related. Therefore, it is ridiculous to say that everything can be demonstrated on the ground that there are such things as circular demonstrations.
Now the reason is obvious why in a circular demonstration all the propositions must be convertible. For it has been shown in the book of Prior Analytics that if one thing is laid down, another does not follow of necessity, whether the thing laid down be one term or one proposition. For every syllogism must start with three terms and two propositions as a minimum. Therefore, in a circular demonstration three terms which are convertible must be taken, namely, A, B, C, such that A is in every B and in every C, and these, namely, B and C, must inhere in each other, so that every B is C and every C is B, and also inhere in A so that every A is B and every A is C. And so, the terms being thus related, it is possible, when using the first figure, to derive any one from any two circularly, i.e., the conclusion from two premises and each premise from the conclusion and the remaining premise, as we pointed out in the Prior Analytics, where we treated the syllogism formally.
The way it is done is this: take the three convertible terms, “risible,” “rational mortal animal” and “man,” and form the syllogism:
- Every rational mortal animal is risible;
- Every man is a rational mortal animal:
- Therefore, every man is risible.
Then from the conclusion it is possible to conclude both the major and the minor; the major thus:
- Every man is risible;
- But every rational mortal animal is a man:
- Therefore, every rational mortal animal is risible
and the minor thus:
- Every risible is a rational mortal animal;
- But every man is risible:
- Therefore, every man is a rational mortal animal.
However, it has also been proved in the Prior Analytics that in figures other than the first, namely, in the second and third, one cannot form a circular syllogism, i.e., one through which each of the premises can be syllogized from the conclusion; or if one is formed, it is done not by using the premises already used but by using propositions other than those which appear in the first syllogism.
That this is so is obvious. For the second figure always yields a negative conclusion. Consequently, one premise must be affirmative and the other negative. However, it is true that if both are negative, nothing can be concluded; and if both are affirmative, a negative conclusion cannot follow. Therefore, it is not possible to use the negative conclusion and the negative premise to obtain the affirmative premise as a conclusion. Hence, if this affirmative is to be proved, it must be proved through propositions other than the ones originally used. Again, in the third figure the only conclusion ever obtained is particular. However, at least one premise must be universal; furthermore, if either premise is particular, a universal cannot be concluded. Hence it cannot occur that in the third figure each of the premises can be syllogized from the conclusion and the remaining premise.
For the same reasons it is obvious that such a circular syllogism (through which each premise could be concluded) cannot be formed in the first figure except in the first mode, which is the only one that concludes to a universal affirmative. Furthermore, even in this mode the only case in which a circular syllogism could be formed such that each of the premises could be concluded, is when the three terms employed are equal, i.e., convertible. The proof is this: The premise must be concluded from the conclusion and the converse of the other premise, as has been stated. But such a conversion of each premise is impossible (for each is universal), except when the terms happen to be equal.
I have claimed that science, a handmaiden of theology, is grounded not only by reason but also by faith—i.e., faith that knowledge of God from the created world (Romans 1:20) is possible through the senses because God's grace builds on our human nature. "[F]aith is the substance of things to be hoped for, the evidence of things that appear not" (Hebrews 11:1); it is an intellectual assent; it "is a kind of knowledge, inasmuch as the intellect is determined by faith to some knowable object" (Summa Theologica Iª q. 12 a. 13 ad 3). I do not mean that with sola fide (faith alone) one obtains intellectual knowledge as a fideist, one who agnostically "affirms that the fundamental act of human knowledge consists in an act of faith" and "denies intellectual knowledge," maintains (Sauvage, G.); no, intellectual knowledge comes from the senses (Nihil est in intellectu quod non prius in sensu.). St. Thomas the Apostle, through his desire to know, had faith that he could, and Christ, knowing that humans obtain intellectual knowledge via the senses, told him physically to touch Him, and he believed. For the same reason, Christ instituted the sacraments, physical signs of an invisible reality.
If, however, the lower sciences are indeed handmaidens of theology (Summa Theologica Iª q. 1 a. 5 s. c.), unified in this study of God, the supreme science, and if the "articles of faith" afford knowledge of God and His revealed truths for theology to adopt as its principles (Summa Theologica Iª q. 1 a. 7 c.), then why does it seem the truths of theology do not help the lower sciences like physics, chemistry, and biology, or vice versa? If they would—were modern science, far from being true science, not generally atheistic—then the ultimate source of all the sciences' principles would be the "deposit of faith," Revelation. But how? How do these truths from Revelation come to us as a result of having faith? They still come through the senses, except in very rare visions "accompanied by abstraction from the senses" (Summa Theologica IIª-IIae q. 173 a. 3).
On the necessity of believing things which can be proven by natural reason, St. Thomas says
It is necessary for man to accept by faith not only things which are above reason, but also those which can be known by reason: and this for three motives. First, in order that man may arrive more quickly at the knowledge of Divine truth. Because the science to whose province it belongs to prove the existence of God, is the last of all to offer itself to human research, since it presupposes many other sciences: so that it would not be until late in life that man would arrive at the knowledge of God. The second reason is, in order that the knowledge of God may be more general. For many are unable to make progress in the study of science, either through dullness of mind, or through having a number of occupations, and temporal needs, or even through laziness in learning, all of whom would be altogether deprived of the knowledge of God, unless Divine things were brought to their knowledge under the guise of faith. The third reason is for the sake of certitude. For human reason is very deficient in things concerning God. A sign of this is that philosophers in their researches, by natural investigation, into human affairs, have fallen into many errors, and have disagreed among themselves. And consequently, in order that men might have knowledge of God, free of doubt and uncertainty, it was necessary for Divine matters to be delivered to them by way of faith, being told to them, as it were, by God Himself Who cannot lie.The Italian writer and apologist Alessandro Manzoni (1785-1873) said this about faith, which really reminds me of what is happening in science where it meets with Catholic morality; true science always conforms to true faith:
Have you examined all these objections [against Revelation]? Objections of fact, of chronology, of history, of natural history, of morals etc. Have you discussed all the arguments of the adversaries, have you recognized their falsity, unfoundedness?... this is not enough to have faith in Scripture. It is possible, it is unfortunately possible that in the generations to come... there will be some men who will study new arguments against the truths of the Scriptures; they will rummage through history, ... they will pretend to have discovered truth of fact for which the things affirmed in the Scriptures have to appear false. Now you must swear that these arguments that are not yet found, will be false, that these books that are not yet written, will be full of error: do you swear it? If you deny it, you admit to not having faith.If one understands this, then one can understand why Pope Paul VI—the pope of the controversial encyclical Humanæ Vitæ which correctly condemned as immoral any form of contraception—would advocate St. Thomas Aquinas's "perennial philosophy" for anyone seeking truth, including, e.g., modern physicists:
—Alessandro Manzoni's Morale cattolica, vol. II, pp. 544-545 [my translation]
[...] to be a faithful disciple of St. Thomas today, it is not enough to want to do in our time and with the means available today that which he did in his. Contenting oneself with imitating him, like walking on a parallel street without anything to draw from him, one would with difficulty arrive at a positive result or, at least, offer to the Church and to the world that contribution of wisdom which they need. One cannot, in fact, speak of true and fecund loyalty if one does not receive, almost from his own hands, his principles which also illuminate the most important problems of philosophy and, to be more precise, to understand better the faith in these our times and, similarly, the fundamental notions of his system and the force of his ideas. Only so, the thought of the Angelic Doctor, confronted always with new contributions of profane science, will meet—through a sort of mutual osmosis—a new, thriving, lively development.Hence, in light of all we have said, one must indeed have faith in order to come to a fuller understanding.
—Pope Paul VI's 1974 letter Lumen ecclesiæ 29. [my translation]