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The following is Part IX in a series defending the claims of the Catholic Church. Read Part I here; Part II here; Part III here; Part IV here; Part V here; Part VI here; and Part VII here; and Part VIII here.

(LifeSiteNews) — The previous instalment of this series asked “what is philosophy?” and answered the question as follows: philosophy is “the science of all things naturally knowable to man’s unaided powers, in so far as these things are studied in their deepest causes and reasons.” 

In this article we will ask whether it is possible for there to be one system of true philosophy and whether that system can be identified.  

This is an important question because today it is common to regard philosophy as essentially non-scientific and as merely a collection of different ideas about the world and about life, from which one can pick and choose as one wills.  

Most people seem to assume that philosophy is not very important and will not affect “real life” very much. A person might enjoy reading Plato, or Nietzsche, or Marcus Aurelius, in his “free time” but his “real life” will proceed along much the same lines as everybody else in his society.   

The unreality of philosophy for modern man is a consequence of the ideas of Kant, and the schools of philosophy which follow him, which hold (as explained in a previous article), that the human intellect cannot attain to certain knowledge of reality beyond sensory phenomena. 

If this is the case, then nothing truly meaningful can be said by philosophy and real knowledge is restricted to the empirical sciences.  

Commenting on such attitudes, Cardinal Mercier writes: 

According to one opinion which is seldom expressly formulated but which we may say is none the less “in the air” the special sciences have nowadays monopolized everything that can be the object of such knowledge as is certain and can be subjected to verification… If then philosophy has a claim to exist, it can only be as a science outside positive science, busying itself with shadowy speculations and contenting itself with fictions for its conclusions or, at least, with conjectures that cannot be verified.[1]

But, as we saw in the previous article, philosophy actually ranks above the particular sciences, because it abstracts from their findings and seeks their ultimate causes and reasons. 

Thus, the Cardinal continues: 

Such an opinion arises from a failure to understand the role philosophy thinks it right to assume and, in consequence, the scope of its claims.  

Philosophy does not profess to be a particularized science, with a place alongside other such sciences and a restricted domain of its own for investigation ; it comes after the particular sciences and ranks above them, dealing in an ultimate fashion with their respective objects, inquiring into their connexions and the relations of these connexions, until finally it arrives at notions so simple that they defy analysis and so general that there is no limit to their application.   

So understood, philosophy will exist as long as there are men endowed with the ability and energy to push the inquiry of reason to its furthest limit. So understood, it is a living fact, and it has a history of more than two thousand years.[2]  

Today, the so-called study of philosophy is often actually the study of the history of philosophy, a quite different discipline. The history of philosophy forms part of the science of history and is the study of what philosophers of the past have believed. This is not the two-thousand-year-old philosophy of which Cardinal Mercier speaks. That philosophy is the study of the totality of reality itself and its conclusions form a permanent, and true, body of knowledge. 

This body of knowledge still exists, and it must be recovered, for without it, human knowledge is incomplete   

The body of sciences without philosophy is like an arch without a keystone. No structure that is built upon it can stand. Philosophy is the stone which ensures that all the stones achieve their collective goal of forming the structure of true human knowledge.  

Philosophy is of crucial importance to everyone: 

  1. Individuals benefit in an obvious way from understanding the world around them more deeply. Philosophy leads us to an understanding of the fabric of reality, including the operations of our souls, the nature of God, and the ethical principles that should inform our actions.
  2. Society benefits from the true philosophy because the common good requires those who govern and legislate to do so based on correct principles. 
  3. The Church benefits, because philosophy helps us explain to the doctrine of the faith more clearly. We will see later in this series, that the Church’s esteem for the true philosophy is such that she has included its terminology in her infallible, irreformable, definitions of revealed doctrine. 

Therefore, we cannot be satisfied with treating philosophy as a hobby, merely reading certain writers in our leisure time while our minds continue to operate according to the script provided by the modern world.  

The fundamental questions of life, of meaning and morality, cannot be answered by the empirical sciences. If we are not satisfied by the empty answers that pass for wisdom in the modern world, we must turn to philosophy for answers. 

We have an interest in asking whether there is one philosophy which is true, and if so, which it is.  

Man is a capable of developing a true philosophy 

Man is a rational animal. We seek the truth, and the human intellect is capable of attaining true knowledge. We have already seen that, from the perspective of supernatural faith, the reliability of the senses and the capacity of the human intellect to attain certain knowledge is upheld by the infallible teaching authority of the Catholic Church.  

But we do not need supernatural faith to realize this. The process by which we form reliable judgments has been discussed in an earlier article.  

But as an example of the capacity of the human mind to reach knowledge by abstraction, consider the extraordinary applicability of mathematics. 

In mathematics, the intellect abstracts from concrete objects and deals in abstract quantities, numbers. From this simple foundation, the human intellect attains complex structures of knowledge, which when applied to reality are shown to reflect reality: aeroplanes fly, satellites orbit the earth, mobile phones present this article for you to read, and so on.   

Our everyday actions, such as the fact that we choose to get on a plane and expect to arrive safely at our destination, demonstrate our conviction in the reliability of human knowledge. 

There is therefore no good reason to deny this reliability in the realm of philosophy. Philosophy uses the same abstracting and reasoning powers as mathematics. It reaches conclusions that are also certain.  

Of course, mankind is afflicted with ignorance and sin, our intellects are darkened, and our wills are weak, but despite this man is capable of building up a true philosophical system. 

Given that such a system can exist, is it possible to identify which of the competing systems is the true philosophy. 

Monsignor Paul Glenn outlined three marks that can help us to identify that philosophy which is true[3].  

Mark One: “True philosophical doctrine must exhibit itself as enduring, as historically continuous.”

True philosophical doctrines, being true, will also be enduring, they will persist throughout human history. New theories may arise for a time, but, to the extent that they are erroneous, they will be abandoned and there will be a return that which has proved its worth. Insights that are true will be incorporated into the wider philosophical system. 

For example, we can see that in ethics there is a remarkable unanimity across cultures and across time. Certain cultures, at certain times, may find philosophical justification for acts which most cultures regard as unethical, but these are exceptions to the general consensus of mankind. 

Mark Two: “A true philosophical doctrine will fit in with others of its kind in a sort of interlocking security, so that there is a true consistency in the system of such truths.” 

The true philosophy will be consistent as body of doctrine. Its doctrines will complement each other. They will not be contradictory. They will help to explain each other and will have applicability across the different fields of philosophy. And as the system grows, its consistency will become more and more apparent.  

Mark Three: “The true philosophical doctrines must be changeless in themselves.” 

Truth does not change. What is true today will be true tomorrow; what was false yesterday will be false tomorrow. As our knowledge of the other sciences grows, the doctrines of the true philosophy will become more and more evident, and false philosophies will be exposed and fade away.  

These three arguments appeal to our natural reason, but there is a fourth that will have weight for those who have supernatural faith: the true philosophy will be that which is compatible with the truths of divine revelation proposed for our belief by the teaching authority of the Catholic Church. 

Does this true philosophy exist? 

Yes, it is the philosophy that has its foundations in the ancient Greek cities of Asia Minor, and which reached its flowering in Socrates, in Plato, and, above all, in Aristotle. 

This is the philosophy which assisted the Fathers of the Church in their exposition of the Christian revelation, it was preserved by the Church when the light of learning was in danger of being extinguished, and burst out in flame again in the great revivals of Christian learning in the ninth and eleventh centuries.  

This is the philosophy which enjoyed its golden age in the High Middle Ages, under the direction of such great minds as St. Albert the Great, St. Bonaventure and most notably, St. Thomas Aquinas.  

This is the philosophy which was a bulwark of the Catholic faith during the Counter-Reformation and at the Council of Trent, where the Summa Theologica of St. Thomas Aquinas was laid upon the altar along with the Sacred Scriptures and the decrees of the Roman Pontiffs. 

Of St. Thomas Aquinas’ influence over the Ecumenical Councils since his death, Pope Leo XIII wrote, “one might almost say that Thomas took part and presided over the deliberations and decrees of the Fathers, contending against the errors of the Greeks, of heretics and rationalists, with invincible force and with the happiest results.”[4]

This is the philosophy whose decline was contemporary with the falling away of the Western mind from reason and sanity, and whose revival under a succession of Roman Pontiffs provided new hope that “all things might be restored in Christ.”

This is the philosophy which was abandoned during the apostasy following the Second Vatican Council, and which has ushered in the darkest era in the history of the human race. 

This philosophy is the embers from which the fire of Western civilization must once again be lit. 

We will trace each stage of this journey in more detail in the articles to come. 


1 Desiré-Joseph Cardinal Mercier, A Manual of Modern Scholastic Philosophy, Vol. I, p1.
2 Mercier, p1-2.
3 Mgr Paul Glenn, Introduction to Philosophy, (St. Louis, 1944), p18-19.
4 Pope Leo XIII, Encyclical Letter Aeterni Patris “On the Restoration of Christian Philosophy”, Nos. 22-23.