Truth endangered by science?

Rev. Robert Brucciani

The Problem

If a modern man desires to understand something, justify a decision or solve the great problems of the universe, more likely than not he will turn to the physical sciences (physics, chemistry, biology and all their offshoots). He does this because good science is at once penetrating, logical and entirely unemotional. He finds that the physical sciences will give him answers most of the time, they are free from ideology and they will tell him the truth.

Indeed, it would probably not be unfair to suggest that most modern academics hold that if the physical sciences cannot draw conclusions about something, then it is either unknowable (at least for the moment) or falls into the realm of personal opinion which is entirely subjective and so can happily differ from person to person. The physical sciences, therefore, are held to be the highest source of truth.

To hold this view is problematic, for the further one looks into outer space or the more closely one examines physical matter, the more elaborate and incomprehensible the universe appears and the more uncertain one becomes about what is absolutely true. And with no certitude about the absolutely true, it is not a big step to surmise that absolute truth is unknowable. And, if we can't know the absolute truth, we can't know what is absolutely right and absolutely wrong. In summary, if we rely on the physical sciences as our highest source of truth, then the moral compass of man becomes little more than a weather vane indicating the direction of the latest useful or desirable theory. This is exactly what is happening today and it is a big problem.

The Cause: Rationalism

“We don’t need no Revelation”

To discover the roots of the problem, we must cast our minds back as far as the fifteenth century, to the early years of the renaissance. During this period, there was an acceleration in the development of the physical sciences arising from the increasing affluence and leisure time of the educated classes and an appreciation of the physical sciences’ potential for commercial gain. This development led to a gradual divorce of the physical sciences from Aristotelian philosophy (as the latter was not able to keep up with the pace of discovery) and, happening at a time of diminishing respect for the Church, emboldened many to challenge the existing order of knowledge and to fall into the error of rationalism.

Rationalism, in the wide sense of the term, holds that human reason is the sole source and final test of all truth. Divine Revelation, therefore, being subject to human reason, cannot tell us any truths above reason with any pretension of authority over reason. In short, a rationalist will tell you that you should only hold to be true those things that you can fully understand.1

Rationalism, in effect, deposes Divine Revelation as a source of truth and elevates the physical sciences in the hierarchy of the sources of truth. This presents a grave danger to reason, for Divine Revelation not only reveals mysteries to us, it also safeguards reason by revealing things that we can also know by reason so that we do not accidentally fall into error. These knowable truths are called preambula fidei and include truths such as the existence and attributes of God, the natural law, the immortality of the soul, etc.

“We don’t need no thought control”

Divine Revelation was not the only victim of the march of the rationalists. In an attempt to reduce the spiritual order to the physical order in the mind of man, the physical sciences were deployed to destroy the highest source of natural truth—metaphysics.

Metaphysics is the natural science to which all other natural sciences (including the physical sciences) are subject. Metaphysics is the science which has being as its object and so, as everything that is has being, all things (including God) fall under its gaze. Metaphysics underpins the other natural sciences by giving us an understanding of the essence and nature of all things. Just as the science of biology can be seen as underpinning the sciences of zoology and botany by its understanding of living beings in general (from the aspect of their material composition and comportment), the science of metaphysics underpins all the other natural sciences by its understanding of beings in general. Indeed, no legitimacy can be given to any scientific reasoning without metaphysics because it furnishes us with the first principles of reasoning, without which we could not claim to know any truth.2 Metaphysics, therefore, is the highest natural source of truth.

The rationalists overthrew metaphysics through the philosophy of Immanuel Kant (1724–1804) in his famous Critique of Pure Reason (1781) which denied that human reason could attain to the underlying nature or essence of things. According to Kant, knowledge is always the result of experience and, since it is experienced by us, it is not, and could never be, knowledge independent of our minds. Since it is not independent of our minds, then it cannot be considered real for reality is independent of the human mind. For Kant, the only things that are independent of the human mind are Dinge an sich—"things in themselves|—and these are intrinsically unknowable.

The problem with this view is that if we cannot know things as they are in themselves to any degree (i.e. if we cannot have reality control our thoughts), then we cannot know truth.

Kant’s philosophy of transcendental idealism gave birth to a whole family of deviant philosophies (positivism, existentialism and phenomenology) which have this in common: they all deny man’s ability to know an objective truth. The rationalist tyrants, discarding revelation and destroying metaphysics, built their house upon the physical sciences and took as their motto, “It is absolutely true that absolute truth is unknowable.”3

The Result: Religion of Man

In a well ordered world, the posturing of an emperor clothed in nothing but the physical sciences and spouting transcendental idealism would ordinarily be short-lived. The absurdity of claiming that the physical sciences are the highest source of truth, whilst simultaneously denying the knowability of absolute truth, would be spotted and systematic exposure and would restore the correct order of things. This, unfortunately, has not happened in modern times, for the academic community (and the establishment in general), ignorant of sound philosophy (of which metaphysics is the highest discipline), appears to have gone after a new religion—a religion where man is his own God.

Support for this new religion is readily supplied by the unsavoury productions of mass media. Rarely a week goes by now without the parading of a celebrity scientist to shore up the belief that the physical sciences are the highest source of truth and show that God probably does not exist.

Celebrity scientists are generally academics from the best universities in the world (often introduced as “leading scientists”) who publish jaunty exposés of modern scientific theory and pour witty scorn upon those truths traditionally taught by the Church, which have not been “proved” by modern science.4 In the popular consciousness they have created the erroneous notion that the Catholic faith is opposed to science and is something only for simple folk. They have made man the measure of truth and the physical sciences the new gospel. The irony of course is that such a religion requires a much greater act of faith than the True Religion ever did, for it is fundamentally unreasonable.

Their deception succeeds because, in every lie, there must be some degree of truth. The celebrity scientists are not wrong in saying that there is truth in what physical sciences tell us (e.g. that the speed of sound in air at one atmosphere pressure is 340.29m/s; or that lead has a density of 11.34g/cm³), but they err in overestimating the certitude of their truths. Now, if we can make a man understand this last point, then perhaps we can lead him to an understanding of the order of sciences and hence the order of truth.

The Solution

Understanding the Nature of Truth

There are two sorts of truth, ontological truth and logical truth. Ontological truth is the conformity of things with the Divine Intellect. All things exist according to the Divine Plan, they are the creations of the Divine Architect (the Triune God, not the god of the Freemasons) and, in as much as they conform to the Divine Plan, they are true. As everything conforms to the Divine Plan in their being, then everything that exists is ontologically true.

Logical truth, on the other hand, is the conformity of an intellect with a thing known. When an intellect has the truth, it is entirely conformed to the thing that it knows (its object). For example, when a man apprehends a sphere placed in front of him, then he possesses the truth. Similarly, when a man makes a judgement about something (e.g. the dog has fleas), he possess the truth if this judgement is borne out by reality.

Logical truth is the truth that concerns us in this article.

Understanding the Nature of Certitude

Now, when a man is presented with a proposition, he may have several states of mind in relation to this proposition. His mind might be in a state of ignorance (unable to say anything about the truth or the falsity of the proposition), he could also be in a state of doubt (being inclined to think it false), he might hold the proposition as an opinion (holding it as true while accepting that further evidence might contradict this judgement), or, finally, he might have certitude in relation to the truth of the proposition (holding the proposition as true to the exclusion of all reasonable doubt).

Certitude, however, is susceptible to degrees. For example, the certitude one has about a part of a thing being never greater than the whole thing (e.g. a slice of cake is never greater than the whole cake) is going to be greater than the certitude one has about the truth of Newton’s Second Law of Motion. Commonly, there are recognised to be three kinds of certitude in the natural order of things: metaphysical certitude, physical certitude, and moral certitude.

Metaphysical certitude is that with which self-evidently necessary truth is known, or necessary truth demonstrated from self-evident truth. The demonstrative sciences, such as geometry, possess metaphysical certitude. The contingent fact of one's own existence, or of one's present state of feeling, is known with metaphysical certitude. In the natural order, metaphysical certitude is the highest degree of certitude one might have.

Physical certitude is that which rests upon the laws of nature. These laws are not absolutely unchangeable, but subject to the will of the Creator; they are not self-evident nor demonstrable from self-evident truth; but they are constant, and discoverable as laws by experience, so that the future may be inferred from the past, or the distant from the present. It is with physical certitude that a man knows that he shall die, that food will sustain life, that a brick will accelerate at about 9.81 m/s² downwards when dropped from the top of building. Physical certitude about the nature of a thing, therefore, is what a good scientist might have when he draws conclusions from sufficient experimental data.

Moral certitude is last on the list and is that certitude with which judgments are formed concerning human character and conduct. It is moral certitude which we generally attain in the conduct of life, concerning, for example, the friendship of others, the fidelity of a friend, or the occurrence of certain historical events, such as the Protestant Reformation or the French Revolution. Though almost any detail in these events may be made a subject of dispute, especially when we enter the region of motives and try to trace cause and effect, and though almost any one of the witnesses may be shown to have made some mistake or misrepresentation, yet the occurrence of the events, taken in the mass, is certain.

There is, however, a certitude higher than any natural certitude. It is the certitude of Divine Revelation held with the supernatural virtue of faith. The First Vatican Council (De Fide, Cap. IV) declares that:

There are two orders of knowledge, distinct both in their source and their object; distinct in their source, for the truths of one order are known by natural reason, and those of the other by faith in divine revelation; and distinct in their object, because, over and above the truths naturally attainable, there are proposed to our belief mysteries hidden in God, which can be known through divine revelation alone.

This solemn affirmation is supported by an anathema against anyone who shall deny that there is an order of knowledge higher than the natural, or who shall say that man can naturally by progress attain at length to the knowledge of all truth (De Revelat., Can. iii).

Order of Certitude

  • Supernatural (e.g. “Jesus Christ is God” can be held with supernatural certitude).

  • Metaphysical (e.g. “A cat is not a fish”5 can be held with metaphysical certitude).

  • Natural Physical (e.g. “Cats like fish” can be held with physical certitude).

  • Moral (e.g. “This cat will eat the whole fish” can be held with moral certitude).

The Relationship Between Truth And Certitude

Now it must be understood that the truth of a proposition is not determined by the certitude with which one holds the proposition to be true. A member of the Flat Earth Society, for example, exudes an enthusiastic certitude that the Earth is flat, but with little effect on the truth of the matter. The truth of a proposition is determined only by the reality itself.

And then the greatest degree of certitude one has a right to claim about the truth of a proposition is not determined primarily by how passionately one holds to the truth of the proposition, or how flawless is the method one used to arrive at the statement of the proposition, but it is determined primarily by the nature of the reality about which a proposition has been made. A proposition which concerns the behaviour of an individual, for example, can only have moral certitude; it could never have physical or metaphysical certitude.

To summarise the discourse on truth and certitude we can simply say that:

  1.  Truth is determined by the reality.

  2. The greatest certitude one may have about an object is determined by the nature of this object.

Having understood this, we are now in a position to assess the physical sciences more clearly.

Understanding the Limits of the Physical Sciences

The primary limitation of any science is the nature of its object (i.e. what the science looks at). The proper object of the physical sciences is measurable things, which means that the physical sciences can tell us nothing about the things they cannot measure. A physical scientist cannot draw any conclusions about the soul, or the angels or God unless they cause a measurable effect in the physical world. He can say nothing about the Holy Trinity, the comity of grace, or the particular judgement. He cannot (as he often does) claim that these things do not exist. And, of the beings a scientist can take measurements from, he can say nothing of their essence (their formal cause or quiddity), little of their finality (final cause or why they exist) and nothing of their remote efficient cause (their creation).6

When a scientist brings his intelligence to bear on a proper object, all he can speculate upon is its material cause (what it’s made of), its proximate efficient cause (how the matter came together) and the measurable effect it has on other beings around it. And, from the above exposition of the nature of certitude, he can only ever have physical certitude of the things he finds, regardless of what he feels and regardless of the care he has taken.

And the limitation of the physical sciences as sources of truth does not stop there, for the more complex his reasoning, the more elaborate his model, the less right he has even to this physical certitude. The two great scientific theories of the twentieth century—for example Einstein’s General Law of Relativity and Quantum Theory—cannot be claimed to be true except within limits, for they would otherwise contradict each other. One only has to consider the long list of ascendant, triumphant and then abandoned scientific theories across the centuries, to see how uncertain is the truth that the physical sciences can furnish.

Rescuing Truth

By putting too much faith in the physical sciences, modern man has imprisoned himself in the narrow world of the material order. By basing his belief on sola scientia he has closed himself off from realities that he cannot measure and has severed his reason from the anchor of knowable absolute truth. With reason adrift, acts of prudence and all moral virtues are no longer possible. Man, absorbed in himself, can only become enslaved to his passions.

But if we can make our modern man understand the nature of truth, certitude, the limits of the physical sciences and their place in the order of sciences, then, assisted by God’s grace, when he wants to understand something, justify a decision or solve the great problems of the universe, he will lift his gaze heavenward to look upon all things with Eternal Wisdom, and then, with the Truth to guide him, act with unerring prudence.


1. All divine truths are reasonable (as demonstrated by the science of apologetics), but, except for the preambula fidei, they cannot be fully understood; they necessitate our adhesion by the supernatural virtue of faith.

2. The very first principle of reasoning is, “It is impossible for a thing to be and not to be at the same time and in the same way.” Now, because a first principle is first, it cannot be demonstrated, for there are no higher principles to demonstrate it by. We must accept it, for to reject it would be to fall into the absurd.

3. It is interesting to note that St. Thomas says of those who deny that the possibility of knowing the truth: “they do not differ from plants”—Si autem non concedunt omnia significare aliquid, tunc non differunt a plantis (Metaphysica IV).

4. Richard Dawkins' God Delusion is a classic example. Fr. Thomas Crean, O.P. has provided a comprehensive refutation of this work in God Is No Delusion (Ignatius Press, 2007. ISBN 9781586172312).

5. N.B. a catfish is not a cat!

6. These questions are answered by the higher science of cosmology, which is sometimes confusingly called physics in the domain of philosophy.



Fr. Dominic Bourmaud, One Hundred Years of Modernism (Angelus Press, 2006. ISBN 1-892331-43-8".

The Catholic Encyclopaedia Online Edition. 2003.

David Berlinski, The Devil's Delusion: Atheism and its Scientific Pretensions (Crown Forum. 2008, ISBN 978-465-01937-3",

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  • 1All divine truths are reasonable (as demonstrated by the science of apologetics), but, except for the preambula fidei, they cannot be fully understood; they necessitate our adhesion by the supernatural virtue of faith.
  • 2The very first principle of reasoning is, “It is impossible for a thing to be and not to be at the same time and in the same way.” Now, because a first principle is first, it cannot be demonstrated, for there are no higher principles to demonstrate it by. We must accept it, for to reject it would be to fall into the absurd.
  • 3It is interesting to note that St. Thomas says this about those who deny that the possibility of knowing the truth: “they do not differ from plants” “Si autem non concedunt omnia significare aliquid, tunc non differunt a plantis” (Metaphysica IV)
  • 4Richard Dawkins' God Delusion is a classic example. Fr. Thomas Crean O.P. has provided a comprehensive refutation of this work in God Is No Delusion (Ignatius Press, ISBN 9781586172312)
  • 5N.B. a catfish is not a cat!
  • 6These questions are answered by the higher science of cosmology which is sometimes confusingly called physics in the domain of philosophy.