Introductory Essay

Introduction: Christianity and Medieval Philosophy

During the final stages of Greek philosophy, Christianity made its appearance, affirming and diffusing itself in the Hellenic world as the one true religion, revealed by God and announced to men by Jesus Christ, the God-man.

Christianity indeed has a great history, to which, directly or indirectly, the entire story of humanity is related. Its value, however, is religious, theological, dogmatic, and not philosophical. Still Christianity and philosophy, though moving on different planes -- the former on the plane of revelation and the latter on that of reason -- cannot be foreign to one another.

We know that the supreme purpose of philosophy is to give a solution to the problem of life through the full use of human reason. This solution is present in the content of all those revealed truths which Christianity offers as the object of faith, truths which are made concrete in the dogmas of theism, of creation, of the cause of evil, and of the means by which man can redeem himself from evil and attain happiness. But philosophy, understood as the science which resolves the question of life, is also faced with these same problems, which were confronted and in part resolved by Greek philosophy.

It has been the task of Christian thought to return to these problems and to give a solution to them in accordance with the content of dogma. But it was not possible to carry out this work of rational systematization until Christianity had been promulgated as revealed religion and systematized in dogmas.

Historically and logically the story of Christian thought is divided into three periods: The Period of Evangelization, which occupies the entire first century of the Christian era, during which Christianity is diffused as revealed religion, hence containing truth within itself and having no need of rational justification. The Patristic Period, which runs from the beginning of the second century through the eighth century. During this period Christianity was forced to defend itself against the errors which threaten it from without (paganism) and from within (heresies),

and the Church Fathers worked out the systematization of the dogmas of Christianity. The Scholastic Period, which runs from the ninth to the sixteenth century. Here Christian thought, utilizing Greek speculation, created its own philosophy in harmony with the dogmatic teaching which had been systematized by the Fathers of the Church.

The first and second periods have very great value for an understanding of the Christian religion. This fact, however, does not affect this outline-history of philosophy, which has as its purpose the recounting of the history of thought. Therefore the exposition of these periods will be brief and will have in view the end of placing in relief only those phases which tend to give a solution to the problem of life which is within the scope of philosophy.

Scholasticism, on the other hand, which is the philosophical explanation of Christian thought and one of the most important syntheses in the history of philosophy, will be expounded in its greatest representatives with a fullness consonant with the limits of this outline-history.

An Overview of the Period

The Perfecting of Philosophy in Medieval Times

This essay discusses the rounding of philosophy into full and relatively complete form (perfecting it) in the Scholastic System, the best synthesis that man had been able to achieve up to that time. This was the beginning of the "perennial philosophy" in mature form, ready to serve man in his studies and investigations, to guide his thinking into rich and profitable fields, and to assure the sane advance of true science. This essay looks into the forces and influences that made for the perfecting of philosophy and outlines the work of the more notable philosophers of the Period of Perfection.

Part I: The Factors of Perfection in Philosophy


By the "factors" of the perfecting of philosophy we mean those facts and circumstances which proved to be strong influences upon the thinking of scholarly men, stirring them to philosophic effort. Of all such factors, -- and there must have been a rather large number of them, -- we choose for mention and brief discussion only three; these we deem the most important of all. They are, first, the intellectual atmosphere in which men of genius went to work; second, the questions that engaged their special attention; third, the equipment with which they undertook their task.

Of course, the men themselves, the thinkers, the philosophers, were the greatest "factors" in the progress they made. But it seems somewhat inaccurate to call them by that name, as though they were but an element in a kind of mechanical process that worked inevitably and automatically. We dare not degrade great gifts of mind, great patience, and tireless labors, by naming them so harshly. Therefore, we shall understand "factors" in the sense explained in the preceding paragraph, not as men or as the gifts of men's minds and spirits, but as things that helped to stir men of great mind and great diligence to the task of bringing philosophy to a perfected state.


By the "atmosphere" we mean what may be called the spirit of the times, the interests and the temperaments of people. Now, beginning in the late 8th century, and extending through a period of about six hundred years, there was current in Europe a spirit, -- always strong and often widespread, although never, of course, universal, -- for deep study, for living with "the things of the mind"; in a word, for philosophy. Without such an atmosphere, philosophy could not have matured. As a plant requires suitable soil and climate, with a proper amount of light, heat, and moisture, so philosophy, -- considered objectively, -- requires a suitable intellectual climate or atmosphere in which to attain its growth.

In the 8th century a new spirit appeared in Europe; a spirit for learning. This fact was first made manifest in the multiplication and the enlargement of schools, especially of the parish schools and the cathedral schools. The spirit of learning was fostered by Charlemagne who brought to the continent from the British Isles the learned Alcuin and a staff of teachers to take charge of the palace school (the Palatine School) and to make it a proper model for the others. Through the centuries a zeal for learning grew among the people.

The 14th century found the European world furnished with many great universities, -- Cracow, Rome, Bologna, Paris, Cologne, Oxford, Cambridge, and others. All of these were Catholic, for European civilization was Catholic; all were fostered and furthered by ecclesiastical power.


One of the most important themes of discussion in the age of which we now speak was that of the nature and value of knowledge. This metaphysical question, basic in philosophy, was focussed upon the elements of human knowledge, our ideas. Now, ideas are, in themselves, universal ideas, and the realities which they represent in our minds are represented there in a universal manner. When, for example, we have the idea or concept of "tree," we have knowledge of what tree means; we can write the definition of tree as such;

the definition is applicable to each and every possible tree, regardless of size, location, botanical class. For, we know an essence, and we know it as abstracted from the circumstances and limitations that mark the individual things which have that essence in the world of things outside the mind. This is what we mean by saying that ideas are universal ideas, and that we know things in universal.

Now, there is no question that the thing known in an idea or concept is present to the mind in an abstract and universal way. But there can be question about the way in which that essence actually exists in the things that have it. How, for example, does the essence "tree," -- which is the object or "thing known" in the idea "tree," -- exist in the actual trees which exist or can exist in the world of reality outside our minds? Does this essence exist "universally" in each individual tree? Or does each tree merely reflect this objectively existing essence as each of a thousand mirrors reflect the same sun?

Our ideas are applicable to things, or are predicable of things, as constituting their essence or as indicating what must be or may be associated with their essence. Of the five modes called the predicables, the most notable are genus and species. If the idea "body" is predicated of trees, grass, flowers, weeds, moss, vines, and stones, it is predicated as their genus, that is, as an essence which is in each of the things named, and yet is not their entire essence; for the plants are more than bodies, they are alive. If, of the first six items mentioned, we predicate the idea "plant," this is their species, for it expresses their entire essence; the points in which the various plants differ are nonessential or accidental.

Now, the question arises: how does the universal "body" (that is, the essence "body," known in universal) exist in all these things, and in all others called "body"? Do genera and species have actual existence in things outside the mind, and if so, what is the character of this existence? This is the famous "Question of Universals" which was hotly debated for more than four centuries, and indeed is sometimes debated among philosophers today.

The idea is a universal idea. The object of a universal idea (that is, the objective essence known in the idea) is called "the universal." What are universals? What are genera and species? These questions are identical in meaning, and they pose the "questions of universals."

There are four doctrines possible in the matter of universals. Three of these are fallacious; one is correct and true. It required the genius of the 13th century to establish the true doctrine, which we list here as the fourth, that is, Moderate Realism.

1. Extreme Realism (called Ultra-Realism and sometimes simply Realism) holds that there are universal essences in the world of reality outside our minds. There is, for example, a universal essence of man, and of this essence individual men either have only a part or share, or each individual reflects the entire essence as a little mirror reflects the whole sun. This doctrine which comes flatly in conflict with both reason and experience is to be rejected.

2. Conceptualism says that the human mind is built to form ideas, and these have no knowable corresponding reality in the world outside the mind. Individual human minds are like so many Ford motors, all alike, all working the same way. Therefore, universals are really nothing in themselves, they are merely modes of the mind's working. This doctrine which destroys the value of all knowledge and plunges us into the insane contradictions of skepticism is to be wholly rejected.

3. Nominalism says that the mind, faced by a vast and complicated world of individual things, finds it convenient to make groups of these things and to affix a name or label to each group. The basis of the grouping is a "similarity" in things. The names or labels are our ideas. Thus ideas are not representations of essences; they are merely group-names.

There are no truly universal ideas; hence there are no universals. Nominalism is destructive of all knowledge, of all reasoning; it renders science and philosophy impossible; it is full of the contradictions of skepticism, as, for instance, when it affirms a universal grasp of "similarity" even in its detail of the universal grasp of anything. Therefore, nominalism is to be rejected.

4. Moderate Realism (called also Qualified Realism) says that outside the mind only individual things exist. There are no universal essences in the world of creatures. Creatures cannot exist universally, but only individually. But the mind, in forming its universal ideas, follows no mere inner drive of its nature wholly divorced from the things known (as Conceptualism maintains), nor does it merely apply names to groups of "similar" things (as Nominalism teaches).

The mind is able to see wherein a plurality of things are at one. The mind sees, for example, that all trees are trees. It can form the universal idea "tree," and the idea truly represents the reality which makes any tree a tree. In a word, the idea "tree" represents the essence "tree." Only what is present to each tree individually is represented in the mind universally, that is, in a manner abstracted from, or prescinding from, the individual limitations (size, location, botanical kind, number of leaves, etc) which make a tree this individual tree.

The mind knows things really, according to the reality which is their essence, but the mind knows in a mode or manner which is its own. Now, the mind's mode of knowing is the mode called "universality." Hence, the universality of our ideas is in the mind and from the mind, but it is based upon reality inasmuch as the essence which the mind knows universally is actually verified individually in each and every thing which has that essence. Here we see the reason for calling this true doctrine on universals "realism," and at the same time "qualified" or "moderate" realism. For our ideas represent essences really, yet we do not assert that the object of an idea (that is, the essence represented; the "universal") exists as a universal essence outside the mind.

The Question of Universals was not the only theme discussed by the philosophers of the age of the perfecting of philosophy. Far from it. But this is a question of outstanding importance, and it brings with it the study of nearly every important question of metaphysics. For the critical question (which has to do with the nature, value, and extent of human knowledge) is the fundamental question of all philosophy; and the question of universals is the very focus and point of the critical question. Penetrating study of the critical question, and, in special, of the question of universals, could not fail, and did not fail, to bring with it deep interest and active discussion of all other important philosophical questions.

The themes discussed in the Period of Perfection were, therefore, fundamental and all-important themes. They constituted a notable "factor" in making the age what it was, a time of bringing philosophy to rounded completeness.


The great philosophers of the age of the perfecting of philosophy brought to their task no certified list of credits from some collegiate agency. Nor had they at ready disposal endless libraries of printed books, in most of which, to steal a phrase from C.E.M. Joad, each author thinks it interesting to present the reasons which have led him to formulate his particular brand of error.

The limitations of the times were, in some sense, a benefit. The philosophers had great writings; they had such a library as their times could boast; it was a library that could be known and mastered, and was worth the effort that mastering required. It was not a babble of voices confusing issues and overwhelming the mind with unlimited digression and unrestrained ineptitude.

From the late 8th century there were available for the studious mind the works of Plato and of Aristotle at least in part (although until the 13th century Aristotle was known in Europe in very defective and even falsified translations). There were also the works of Porphyry, Boethius, Victorinus, Macrobius, Apuleius, Cassiodorus, Trimegistus, Hippocrates, Lucretius, Seneca, Cicero, Galen, Martian Capella, St. Augustine, Origin, St, Clement of Alexandria, Lactantius, St. Ambrose, St. Gregory of Nyssa, Nemesius, Pseudo-Dionysius, St. John Damascene.


Matthew Arnold says that great creative epochs in literature result from the happy concurrence of two notable powers, -- the power of the man and the power of the moment. It may be truly said that the age of the perfecting of philosophy came from a similar union of powers.

Although we refuse to list the men of the period as mere "factors" of philosophical achievement, we must notice the fact that the age was one of great and gifted teachers. Among these we mention Alcuin, Roscelin, Anselm, William of Champeaux, Abelard, Bernard of Clairvaux, the doctors of the schools of Chartres and St. Victor, William of Auvergne, Alexander of Hales, Bonaventure, Roger Bacon, Albert the Great, Thomas Aquinas, Henry of Ghent, John Duns Scotus, Raymond Lully, William of Ockham. In addition to these Christian teachers the Arabians Averroes and Avicenna, and the Jewish philosopher Moses Maimonides, lent their learning and energy to the philosophical effort of the times.

As for the power of the moment, four items may be mentioned. First, philosophy, ripened by five centuries of intense study, was ready for expression in an orderly and complete synthesis at the opening of the 13th century. Second, the works of oriental philosophy were spread, in Latin translation, through western Europe; these aroused both sympathy and strong controversy, and so proved to be a force in the intellectual movement of the age.

Third, great universities were multiplied and their influence was a strong and steady force for philosophical achievement. Fourth, the religious orders of St. Francis and St. Dominic carried to the common people not only the better knowledge of the Christian Religion but also a great deal of philosophical knowledge; for members of these religious families went everywhere and were often forced to meet on philosophical grounds the thinkers of non-Christian persuasions.

Part II: From Anselm to Albert the Great


St. Anselm of Lombardy (1033-1109), Abbot of the Benedictine Monastery of Bec in Normandy, and later Archbishop of Canterbury in England, was the foremost philosopher of the 11th century.

One of his chief interests, -- which led to only a partial success in the efforts it engendered, -- was the distinction between theology and philosophy. Anselm disagreed with those philosophers (such as Erigena) who held that these are really one science. But it was left for Thomas Aquinas, in the 13th century, to show with scientific exactness that there is a clear line of demarcation between them, and that theology (that is, supernatural theology) is one science and philosophy another.

Anselm offered reasoned proofs for the existence of God and for the Divine Attributes. He argued cogently in evidence of the truth that the human soul acquires intellectual knowledge by abstracting ideas or concepts from sense-findings, and using these in judging and in reasoning, he inclined to the Platonic doctrine that soul and body are united accidentally and not substantially; in this, of course, he was quite wrong.

The heretics of Anselm's day were fond of dialectics, -- that is, of fine logical reasoning; theirs was rather an abuse, than a proper use of logic. Nevertheless, many pious and learned men were led to see in dialectics a kind of snide trickery, and even a devilish device for the spread of error and the confusing of minds. Anselm stood sanely and firmly against this mistaken view of logic. He employed it himself with telling effect, and so routed the heretics with their own weapon. Thus he saved the good name and the splendid service of dialectics for Christian scholars; he justified for all time the use of sheer reasoning and philosophical argument in the exposition and defense of the Christian Faith.

Yet he clearly declared that the Christian had no need to rationalize is Faith; possessing the Faith, reason can serve to show its truth and glory, and so attract those who have it not. The motto of Anselm was "Credo ut intelligam," that is, "I believe that I may understand": "I find in my Faith a great light which aids me in understanding other things; I do not need to philosophize about creatures to justify myself in believing." Another motto of Anselm was "Fides quaerens intellectum," "Faith seeking to understand": that is, "If you have the Faith to begin with, you have a head-start in the work of philosophy; you need not philosophize yourself into an acceptance of the Faith."

Perhaps Anselm is best remembered in our times for his famous ontological argument for the existence of God. This argument is not a valid one, but it has intrigued the minds of thinkers for nearly a thousand years. Descartes, Leibniz, and Spinoza were among famous men to study it, reshape it, and present it. Despite its attractiveness it fails to make conclusive proof. Of course, it is in no wise required. The inescapable force of the a posteriori arguments for the existence and attributes of God make other arguments superfluous.

But Anselm, like many another since his day, thought that an a priori argument could be developed from the fact that man inevitably has some notion of Deity. The famous argument ran thus: All men, even unbelievers, have an idea of God -- it is the idea of the most perfect Being thinkable; Now, the idea of the most perfect Being thinkable is the idea of an existing Being (for, if it lack existence, it lacks a most notable perfection and hence is not the most perfect Being thinkable); Therefore, God really exists.

The fallacy in this argument lies in the fact that it "jumps" from the realm of thought (called the logical order) to the realm of reality outside the mind (called the ontological order), and thus leaves a gap in the reasoning. If we restate the argument, observing the strict rules of logic, we shall see that the conclusion is quite different: God is the most perfect Being that can be thought of; Now, the most perfect Being that can be thought of must be thought of as existing; Therefore, God must be thought of as existing.

This argument is perfectly legitimate. But the fact that God must be thought of as existing cannot be used as a proof that God actually does exist.

Gaunilo, a critic of Anselm's argument, tried to reduce it to absurdity in some such fashion as this: I have an idea of a most beautiful and perfect floating island; Now, unless it exists, it is not most beautiful and perfect; Therefore, this floating island exists.

This nonsense merely proved the fact that Gaunilo did not understand Anselm's argument. For he was speaking of the Fist, the Infinite, the Necessary Being, not of a creatural and limited thing like a floating island. No limited thing can be limitless in perfection. No creature can be envisioned as most perfect.

The very concept of a creature is the concept of thing perfectible. Anselm spoke only of that Being which we cannot help thinking of (and which even atheists cannot help thinking of, for they must have an idea of what they are denying when they deny God) as absolutely perfect, as limitless in perfection, as infinite. No one needs to think of a floating island or of any limited reality. But the idea of the absolute is inevitable to normal and mature minds. Indeed, if the ontological argument did not unwarrantedly assume a priori the objective validity of thought, it would be a cogent and irrefutable proof of God's existence.


Peter Abelard or Abaelard (1079-1142), a native of Brittany, became in early manhood the outstanding teacher of his age. He was universally regarded by his contemporaries as the greatest of living philosophers. In this opinion Peter Abelard wholeheartedly concurred. He was a fiery teacher and speaker, a clever dialectician, a man too intent on triumph in debate.

There were few questions in philosophy upon which he failed to touch; there were few to which he gave thorough and complete treatment. His great service to philosophy is that he stirred up the thinkers; he awoke enthusiasm. Even his errors, championed so earnestly, aroused opposition that led to the clear exposition of many a truth that had been only half understood or but murkily explained.

Abelard rightly maintained that the use of reason is of the greatest value in setting forth the truths of Faith. Yet, despite his tendency to run to extremes, he did not declare that reason is all-sufficient (rationalism) for the full understanding of every truth. Hence it is not just to call Abelard a Rationalist, as too many have done.

In the matter of universals Abelard came near the right doctrine of Moderate Realism. In his day the terminology of this question had not been finally formulated, and hence there is some obscurity in his position.

Abelard says that God is so far above expression that all our speech about Him is figurative. Here he is wrong. God is infinite, and our minds and our mode of speech are finite. But, for all that, we can have a knowledge of God that is literally true knowledge, not figurative knowledge, even though it is never exhaustive. All that we know of as absolute perfection (that is, pure or unmixed perfection) we attribute to God literally, though in a transcendent or eminent way.

Abelard thought that God is compelled by His goodness to create, and to create the best of all possible worlds (theological necessitarianism and cosmological optimism). Now, compulsion in God is unthinkable, since He is infinite and supremely independent, and, being the Source of all reality, there is nothing outside God which could conceivably work an independent influence upon Him. Nor is there anything within God to compel creation. All that God has, He is. God's Goodness is God Himself eternally subsisting.

Hence the idea of compulsion in or upon God is a self-contradictory notion. God is not obliged in any way to create, nor, freely choosing to create, is He obliged to create the best of all possible worlds. It is sufficient that His work be worthy of Him; that it be splendidly suitable for achieving the end for which it is made.

In his studies upon the ethical question, Abelard rightly holds that God is the Supreme Good towards Which man of necessity tends. God is the ultimate end of man in all human acts. And the possession and enjoyment of this objective End is the subjective last end of man: that is, beatitude in the possession of the Supreme Good. In trying to fix the norm of morality, Abelard hesitates, and finally sets down two opinions, neither of which is correct.

He thinks that the law or line which marks off good from evil (the norm of morality) is either God's will alone, or man's intention. Now, the true norm of morality is God as Eternal Law, that is, God as Divine Understanding and Will, not God as Will alone. God's will is, humanly speaking, consequent upon His knowledge of what is in line, and what is out of line, with Himself.

Man's intention cannot be the norm of morality. It is a determinant of morality in so far as a bad intention can spoil a good act and make it evil; but a good intention cannot save a bad act and make it good. The norm of morality is The Eternal Law; it is applied by human reason judging on the objective right or wrong of a situation here and now to be decided; in this service, human reason is called conscience.