Philosophy of The Middle Ages

Periods in the Development of Medieval Philosophy: Specificity, Key Representatives, Fundamental Ideas

The development of medieval philosophy is generally divided into three stages: apologetics, patristics, and scholasticism.

Apologetics (from the Greek apologia — to defend, to justify) is characterized by the defense of Christian doctrine against attacks from pagans, secular rulers who adhered to polytheism, and philosophers who critiqued the tenets and postulates of Christianity. It emerges as a distinct form of philosophical argumentation aimed at justifying Christian beliefs through philosophical means.

Key figures in apologetics include Athenagoras, Hippolytus, Irenaeus, Clement of Alexandria, Justin Martyr, Tatian, Theophilus, Minucius Felix, Tertullian of Carthage, among others. The earliest apologies were written around the mid-2nd century. One of the first apologists, Justin Martyr, in his "Apology," argues for the primacy of Christianity over pagan philosophy, developing his arguments through proofs of universality, simplicity, unity, authority, and antiquity—though these are not the only forms of argumentation used. In harmony with him, another apologist, Clement of Alexandria, notes: “A teaching accompanied by proof firmly establishes faith in the mind of the researcher, leading him to refuse even to imagine the matter otherwise. If we can substantiate the doctrine of faith with evidence, it will protect us from the various deceivers, preventing us from being misled by their delusions.”

Tatian, a contemporary of Justin, continues this line of argumentation in defense of Christianity, asserting that the disunity of wisdom is the chief flaw of pagan philosophy. Without knowledge of God, philosophers dispute among themselves, contradicting one another. This results in their thoughts being fantastical and contradictory, and their morality is questionable, as their teachings often conflict with reality: Diogenes died from gluttony, Aristippus was licentious, and Socrates was condemned to death for corrupting the youth, and so forth. The apologists introduced the principle that "the end justifies the means" into philosophical argumentation. Such means included "argumentum ad personam," or arguments directed at the person, allegories, interpretations, and overt accusations.

Athenagoras, before converting to Christianity, was among the ranks of pagan philosophers and, being a contemporary of Marcus Aurelius, relied on his enlightenment to defend Christians from persecution. In his "Supplication for Christians," he seeks to absolve them of accusations of insurrection, cannibalism, incest, and atheism. The core of his apologetic argumentation is the refutation of the supposed atheism of Christians. His proofs can be distilled into four main points: — Christians believe in a single God, but monotheism does not equate to atheism; — The greatest Greek philosophers and poets were monotheists (including figures such as Plato, Aristotle, Sophocles, and Euripides, who were spiritually close to Marcus Aurelius); — Monotheism is a more logical and adequate belief system that aligns with religious knowledge; — If Greek monotheists are respected, why are Christians—also monotheists—denied the same?

Athenagoras's arguments for Christianity are similarly constructed on the principle of "pro" and "contra," where the more factual and historical errors are found in one, the more convincing the affirmations seem in the others. Although his remaining arguments may not seem original by contemporary standards, they were innovative for their time, as they predated certain aspects of the proofs for the existence of God developed by philosophers over a millennium later.

While the apologetics of the Christian philosopher Athenagoras can be deemed reasoned and justified, Theophilus’s apologetics represent a different approach. He equates the essence of wisdom with faith in revelation, employing "arguments by analogy." For instance, the analogy that became popular later formed the basis of his argumentation: “Just as not all can see an earthly king, yet all know him through his laws, decrees, armies, and images, so too, if you wish to know God, recognize Him through His deeds.”

The apologist Minucius Felix directed all his arguments against the pagan philosopher Caecilius, compiling them into his treatise "Octavius." He employs arguments aimed at refuting assaults directed at Christian dogma and addressing accusations concerning the inaccessibility of theoretical knowledge of religious mysteries. By repelling targeted attacks on the Christian worldview, Minucius laid the groundwork for Quintus Septimius Florens Tertullianus (circa 160-222), a classic figure in apologetics. Tertullian's reflections represent the quintessence of apologetics and can be summarized as follows: — The Christian faith aligns with the demand for simplicity, containing truth in a ready-made form that requires neither proof nor verification; — The Christian faith does not require interpretation of the Gospels; everything should be understood literally, even if it contradicts logic, experience, and the natural order of things. (A telling expression from Tertullian in this context is: “We have no need for any divinity after Jesus Christ, nor for investigations beyond the Gospel. By believing in it, we wish to believe in nothing else, even thinking that there is nothing more to believe.”); — The principle of pure faith can be reduced to: not knowing anything means knowing everything; — The foundational principle of faith (postulate) is “Credo quia absurdum est,” which translates from Latin as: “I believe because it is absurd.” (It is worth noting that there is no authentic statement of this in Tertullian's texts. Instead, he states: “The Son of God was crucified—we do not shy away from this because it is shameful; and the Son of God died—we believe in this because it is absurd; and being buried, He rose again—this is right, for it is impossible.” This paradox is derived from the New Testament, specifically from the letters of the Apostle Paul. Later, it became known as the aphorism “Credo,” meaning “I believe,” “I believe because it is absurd,” which most fully and accurately reflects the essence of Tertullian's religious-philosophical views); — The Christian God is triune (possessing three “faces,” or hypostases): God the Father, God the Son, and the Holy Spirit; — Christian ethics is based on the idea of freedom, the moral choice of the individual, and the necessity of atonement for original sin.

Tertullian dedicated the majority of his theoretical works to the questions of Christian ethics, which he believed were founded on freedom—the freedom of moral choice and the necessity for humanity to overcome original sin. He posited that it was precisely this freedom to choose between good and evil that led to the fall of humankind. Nevertheless, possessing the freedom to choose between sin and sanctity, good and evil, justice and injustice, allows individuals to make the right choice, thus atoning for the transgressions of the first humans and their own sinful actions. Consequently, the idea of guiding one's own freedom of choice became foundational and crucial in the development of legal relations within society.

Tertullian’s principal works include "Apologeticus," "On the Soul," "Against Marcion," "On the Flesh of Christ," and "On the Testimony of the Soul." Thus, apologetics, employing techniques of ancient philosophy and logical proof, defended Christianity to establish its place within society. The primary task of the apologists was to demonstrate that pagan beliefs were not true, that ancient philosophy was contradictory, and that the finest ancient philosophers (such as Socrates, Plato, and the Stoics) had anticipated Christian ideas, while theology proving divine truths was the only correct path compared to ancient wisdom.

The essence of apologetics is the defense of faith, asserting its primacy over knowledge. The dominance of faith over knowledge is indisputable and, in essence, beyond proof. Even when arguments invoke the "proof" of the dominance of faith, this is accomplished not through fact or logic.

Apologetics laid the groundwork for the next phase in the evolution of medieval philosophy—patristics. Characterized by the justification of Christian doctrinal positions and their dissemination among the masses, patristics (from the Latin "pater," meaning father) prioritized faith over reason (4th-10th centuries).

Key representatives of patristics include Basil the Great, John Chrysostom, John of Damascus, Augustine of Hippo (the Blessed), Athanasius of Alexandria, Gregory of Nyssa, and Gregory Nazianzen. They grappled with central problems and dogmas of Christianity, including the essence of God and His trinitarian nature; the Christological problem (the union of divine and human characteristics in Jesus Christ); the interplay of religious faith and reason; revelation as a means of acquiring truth; understanding history as a progressive ascent toward the ultimate goal of the Heavenly Kingdom; anthropological questions concerning divine grace and human sinfulness (the consequences of original sin); human responsibility for actions; free will and the possibility of salvation; the origin of evil in the world; theodicy, shifting responsibility for evil from God to imperfect humanity; and the methods for cleansing individuals from sin and attaining the Heavenly Kingdom. The views of the patristic representatives exemplify a profound immersion of philosophy in theology—the study of God as the first cause and foundation of all existence, the embodiment of absolute perfection.

Patristics represents the theologization of philosophy, wherein the Bible becomes the sole complete collection of all truths. Philosophical knowledge emerges as an interpretation of the meanings encoded in biblical allegories, with all possible truths concealed within them.

The principal theorist of patristics, the systematizer of Christian doctrine, was Augustine of Hippo (354-430). His major works include "Confessions," "On the Blessed Life," "On Free Will," "On Christian Living," and "Monologues."

Augustine’s thought springs from the ancient heritage. He embraced Plato's idea of a divine creator and Aristotle's notion of the first cause of all things. He believed this reconciled ancient philosophy, despite its polytheism, with the ideology of monotheism, positing that it was necessary to further this path and assert faith as the highest form of knowledge, prioritizing it over Platonic ideas and Aristotelian logic.

Augustine understood faith broadly—not merely belief in God but also trust, confidence, and certainty. He contrasted faith-trust not with thought in general, but with understanding, positing that faith is a unique type of thinking that involves agreement, acceptance, and embrace. Faithful thought aligns more closely with its object, merging with it rather than opposing it. Thus, faith transcends reason and draws nearer to truth because trust is a prerequisite for any form of knowledge.

In this way, Augustine's conception of faith extends beyond ordinary religious belief, becoming an integral element of cognitive activity. He argued that the greater the authority, the deeper the trust placed in it, leading to a more profound faith. The highest authority remains the text of Holy Scripture.

Whereas Tertullian's doctrine can be summarized by the postulate "I believe because it is absurd," indicating that one should believe in what cannot be explained by reason, Augustine proclaims a different principle: "I believe in order to understand" ("Credo ut intelligam"). This famous formulation became the central motif of Augustine's philosophical legacy. If, prior to him, reason was subordinated to blind faith, he sought to reconcile faith with reason, ultimately granting the former precedence. One might say he leaned toward harmonizing faith and reason, a concept later fully articulated by the more developed medieval philosopher Thomas Aquinas (1225/26-1274).

The central idea of Augustine's religious and philosophical legacy is the concept of God. He elaborates on the Christian theological doctrine of creation ex nihilo, which asserts that God creates nature through an act of His will—His free will. Absolutely free and uncoerced by any necessity or need, God creates substance (matter), space, and time in a timeless act of creation. Thus, the genetic principle of all that exists—God—is an objectively existing ideal substance, the primal cause of all being. God not only created nature from nothing, but also continually sustains it in existence, perpetually recreating the world through ongoing acts of creation and re-creation. Without this permanent act of creation, nature would collapse into non-existence.

As the creator of nature, God is the source of the natural order. Augustine understood the natural order as the naturalization of ideas—the thoughts of God prior to the creation of the world—which form a descending hierarchy of modes of being, beginning with the highest, incorporeal, and divine, and descending to the lowest, corporeal and material, which barely rises above non-being.

Therefore, God is the supreme, most perfect substance, the ideal form; He exists eternally and is the first cause of all that is, creating the world from nothing, guided by His own wisdom. The process of creation is continuous; God constantly observes and intervenes in earthly affairs, for without this intervention (support), the world would immediately revert to non-being. "In Book XI, 6: There exists heaven and earth. They assert that they were created... Heaven and earth likewise declare that they did not create themselves: 'If we exist, it is a sign that we were created, for there was no us before our existence; hence, we could not have created ourselves.' And this voice of theirs is self-evident.

Thus, it is You, Lord, who created them: You are beautiful, for they are beautiful; You are good, for they are good; You exist, for they exist... This we know, and let thanks be given to You for this; yet our knowledge is ignorance compared to Your knowledge."

All that exists in the world is good, as it is a result of Divine creation, and God is the Good. Therefore, the evil present in the world is a deficiency (lack) of the good that ought to be, a lack arising from human activity, which has chosen the path of sin rather than holiness, of baseness rather than virtue. Evil, thus, is born of the free will of man. Augustine explains the manifestation of evil in the world as a product of Divine creation, justifying God for the existence of evil, injustice, and cruelty, while placing the responsibility for these on humanity, endowed with the freedom of will (theodicy as a fundamental feature of Augustine's religious and philosophical views).

Saint Augustine notes that the first humans—Adam and Eve—were also endowed with the freedom of will before the Fall. However, they misused it, polluting the world, which ultimately led to the self-sacrifice of Jesus Christ. For it was through the death of the Son of God that the sinfulness of the world and humanity was to be overcome.

Augustine believed that the dialogue between man and God begins with humanity's awareness of its sinfulness before God, characterized by sincere repentance and a desire to atone for sin. The path to God, to individual salvation, is paved through heartfelt prayer as an appeal to God, a moral choice in favor of holiness rather than sinfulness, adherence to church precepts, and the “good” deeds of clergy and saints. Believing also that God Himself chooses individuals for salvation, Augustine posits that humanity is saved by God's will.

In his epistemology, Augustine rejects skepticism in favor of supernatural revelation, given to humanity in Sacred Scripture. The source of eternal truths is something eternal, namely God, who bestows upon the human soul both eternal truths and a certain natural light that illuminates the soul. In this illumination, which is not granted to all, humanity, according to Augustine, is capable of directly grasping truth, distinguishing between truth and falsehood.

In his work "On the City of God," Augustine presents a Christian vision of world history while considering the development of society. According to Augustine's teaching, there exist two types of human community: the City of Man, where the devil reigns, alongside evil and sin, and the City of God, or the Christian Church (the Kingdom of God on earth), which stands in opposition to the City of Man. For Augustine, all of history is a struggle between the adherents of the Christian Church, who build the “City of God” on earth, and the followers of Satan, who organize secular life and the earthly state. Sooner or later, the Kingdom of God will triumph over the earthly kingdom. Thus, the primary task of the Church is to combat the world of the devil in order to secure the victory of the Kingdom of God. If the earthly state falls, it will be replaced by the “eternal world state,” embodied in the Catholic Church. All secular authorities, kings, and emperors must submit to the Church (represented by the Pope). According to Augustine, the Kingdom of God will become the sole force capable of uniting a divided world, ensuring progressive development of society. Thus, Augustine advocates for a theocratic system (the supremacy of ecclesiastical authority over secular) and the worldwide dominance of the cosmopolitan organization of Catholicism.

Augustine's philosophy of history sharply contrasts with pagan concepts in this area, which were predominantly characterized by the idea of cyclical recurrence. In his view, the history of human society has a beginning, a purpose, and an end. It is not a senseless repetition, as seen in Marcus Aurelius—a late antique philosopher. The meaning of history lies in the victory of Christianity on a global scale, in the Christianization of all humanity. Its beginning is the creation of the first humans—Adam and Eve. The foundation of Augustine's periodization of human history is the Bible. He divides human history into six periods: five of these periods are linked to Old Testament history; the sixth began with the first coming of Jesus Christ and will conclude with His “second coming,” the Last Judgment, the separation of the sinners from the righteous, essentially designating the chosen for salvation and the unchosen, after which the former will be condemned to eternal suffering in hell, while the latter will experience eternal bliss in paradise.

Despite its fantastical nature, Augustine's philosophy of history laid the groundwork for a theory of social progress, associated with positive changes in the realms of societal and individual morality. The central concern in the relationship between God and humanity, and among humans themselves, is sinfulness. Humanity has sinned against God; in other words, they are sinful. Sin takes on a metaphysical, cosmological, and not merely anthropological significance. By sinning against God and violating His prohibition against tasting the fruit of the "tree of the knowledge of good and evil," humanity has poisoned the entire cosmos. The atoning sacrifice of Christ is required to overcome universal sinfulness, even if only partially.

For Augustine, earthly life is sinful and temporary, serving merely as preparation for eternal "otherworldly" existence. Its goal is the attainment of happiness, which can be achieved through religious faith and mystical self-improvement (introspection). Thus, faith, in Augustine’s view, must precede rational understanding of the world ("I believe in order to understand").

Consequently, Saint Augustine became a theorist of Christian doctrine. The main subject of his religious and philosophical reflections was God and humanity, particularly humanity's likeness to God. Augustine promoted the idea of an ascetic way of life for the sake of attaining eschatological enlightenment and knowledge of divine truths; he founded Christian philosophy of history, presenting arguments in favor of the Church's dominance over the state; and for the first time in European culture, he recorded a model of moral progress, fundamentally rooted in the Christian optimism associated with the triumph of the Heavenly Kingdom on earth.

The next stage in the development of medieval philosophy is scholasticism (from the Greek σχολή—school; σχολαστικός—scholastic, meaning "school" philosophy), characterized by the rational examination of the dogmas of Christian doctrine. These are neither denied nor dismissed. Scholastic philosophers merely seek to provide a logical foundation for them, to prove their truth through logic. The principle of harmony between faith and reason is proclaimed (11th-15th centuries).

Representatives of scholasticism include Peter Damian, Bernard of Clairvaux, John Roscelin, Anselm of Canterbury, Thomas Aquinas, Peter Abelard, and others.

Scholasticism aimed to demonstrate the theological wisdom of Christian doctrine not only through Divine revelation but also through rational thought and, above all, philosophy. The formula of Peter Damian—that philosophy serves theology—encapsulates the essence of orthodox scholasticism. Knowledge, according to this view, is divided into two levels: supernatural and natural. Supernatural knowledge is given in Divine revelation, while natural knowledge is sought by human reason. The authority of the first is represented by the texts of Sacred Scripture (the Bible), and that of the second by the treatises of Plato and Aristotle. At both levels, the "eternal truth" is already given. It merely needs to be extracted from the texts, presented in all its logical consequences, sound reasoning, and conclusions. Thus, from the 12th to the 14th centuries, the theory of "double truth" emerged, according to which it is understood that philosophy leads humanity to truth through knowledge of the surrounding world by reason, while theology understands truth on the basis of religious faith and revelation.

In the history of medieval Western philosophy, Anselm of Canterbury (1033-1109) is often regarded as the first, if not the most classical, scholastic philosopher, and he is rightly referred to as the "second Augustine." Like Augustine the Blessed, Anselm championed the thesis of the primacy of faith over reason: "I believe in order to understand," which implies that while one does not need to understand in order to believe, understanding is contingent upon belief. Anselm held that faith does not contradict reason, and thus all "truths of revelation" (from the Bible) are accessible to rational demonstration, particularly the thesis concerning the existence of God.

In Anselm's teachings, his arguments illustrate the relationship between two types of knowledge. One is attained through faith (the first path), while the other is acquired through reason (the second path), reflecting a supporter of the theory of "double truth." Faith precedes reason, and its tenets serve as an ideal and standard for it. When asked about the necessity of the second path (the path of reason), the response is that while truth is already given to humanity in the tenets of faith, it often requires elucidation. Essentially, within scholasticism, reason acts as a logical, if not technical, instrument of faith; it partners with faith in interpreting Christian dogmas rather than opposing it.

Thus, Anselm of Canterbury stands firmly on the ground of theological rationalism. In the discourse surrounding the nature of universals (general concepts), he aligns with realism.

In many respects, Anselm was opposed by Peter Abelard (1079-1142), a representative of early medieval nominalism and the author of numerous original Latin philosophical-theological works, including "Introduction to Theology," "Christian Theology," "Know Yourself," "Yes and No," "Dialectics," and "The History of My Misfortunes."

For the orthodox Anselm, the authority of faith over reason was indisputable ("I believe in order to understand"), while for Abelard, another formula held sway: "To understand in order to believe." In his view, one can only believe in what has been comprehended by the intellect, what has been grasped by reason, and what is understood. Abelard argued that one must first investigate the content of a religious thesis with reason before deciding to believe or not.

The aim of knowledge is the pursuit of truth. In this context, Abelard attributed crucial importance to dialectics as the art of distinguishing truth from error (delusion). Abelard states: "Even in the Christian faith, there are numerous delusions, for eloquent heretics weave their assertions to ensnare many simpletons into various sects, who, lacking experience in proofs, accept resemblance for truth and illusion for reason. To combat this nonsense in disputes, we are also urged by church teachers to grasp what we do not understand in scripture, not only through prayers to the Lord but also through diligent contemplation."

Thus, Abelard's rationalism is scholastic-theological: the focus of his attention is the proofs of Christian dogmas. He believed that all tenets of the Christian faith could be demonstrated through reason. This is how he attempts to interpret such an evidently "supra-rational" dogma of the Christian Church as the dogma of the Trinity, where the unity is equated with the Trinity. His "Dialectics" is aimed at this.

In "Yes and No," Abelard juxtaposes contradictory statements from ecclesiastical authorities, the "Fathers of the Church," thereby shaking their authority. He sought to reconcile these statements through logical analysis, transforming absolute opposition into relativity.

In the discussion regarding the nature of universals, Abelard occupies the position of moderate nominalism (or conceptualism).

Abelard's ethical views are expounded in his work "Know Yourself." The philosopher distinguishes: 1) inclination towards wrongful acts, 2) a conscious volitional decision to commit such an act, and 3) the act itself. Inclinations, in themselves, are neither good nor bad. An inclination towards evil is not evil and not a sin; it merely reflects a weakness, a natural moral imperfection of humanity. Acts themselves are neither bad nor good because one can commit evil without realizing it. According to Abelard, evil lies in the consent of the will to a known wicked, criminal, and sinful act, the endorsement of a bad inclination. Thus, the criterion of morality for the philosopher is harmony with one's conscience. Conscience, according to Abelard, is the experience of congruence or incongruence between one's actions or inaction and what ought or ought not to be done (or said). He taught that the source of the voice of conscience is a natural moral law, common to all people by nature. Therefore, conscience is given to humanity by nature, and through it, from God. By committing evil (crime, sin), a person acts against the voice of conscience, suppressing it within themselves.

In Abelard's ethical teaching, subjective responsibility is emphasized, stressing the awareness of one's behavior, limiting the sphere of sin, and granting forgiveness to non-Christians who did not know they were doing evil.

The systematizer of medieval scholasticism is Thomas Aquinas (1225/26-1274). Aquinas sought to justify the fundamental principles of Christian theology, relying on the teachings of Aristotle, which he adapted in such a way that they did not contradict church dogmas.

Aquinas endeavored to place philosophy in the service of religion (theology), while also delineating the distinctions between philosophy and religion, knowledge and faith. He argued for the possibility of harmony between knowledge and faith, and the necessity of their coexistence. Thus, Aquinas noted: "...it was necessary that the philosophical disciplines, which derive their knowledge from reason, be complemented by a science grounded in revelation" (Thomas Aquinas, Summa Theologiae, I, q. 1, 1c); and further: "Sacred doctrine is a science" (Thomas Aquinas, Summa Theologiae, I, q. 1, 1 ad 2). Accordingly, he distinguishes between truths of reason and truths of revelation (being a proponent of the theory of "double truth").

Thus, on one hand, Aquinas stands against Tertullian's principle: "I believe because it is absurd," which dismissed the significance of reason in matters of faith, while on the other, he supports Abelard, who argued that religious dogmas should not contradict reason, but rather be in accordance with it. The principle of harmony between reason and faith indicates that the truth discerned by reason (through philosophy) should not conflict with the truth of revelation, which is known within theology (religion).

An example of the interplay between religion and philosophy, from Aquinas's perspective, can be found in the resolution of the problem of proving the existence of God. The philosopher presents five proofs of God's existence, which are fundamentally logical in nature.

The first proof is through motion. Everything that moves must have a first cause of its motion. That first cause of motion (the "unmoved mover," or "first impetus," in Aristotelian terminology) is God.

The second proof is through causality. Everything that exists must have a first cause of its existence. That first cause is God.

The third proof is through the degree of perfection. Everything that exists in the world has a degree of perfection (from simple to complex, from lesser to greater, from less perfect to more perfect). Thus, there must exist the greatest, absolute perfection, which is God.

The fourth proof is through contingency and necessity. Everything in the world exists not contingently, but necessarily. Therefore, there must be a first necessary being—God.

The fifth proof is through purpose (telos). Everything that exists has a purpose for its existence. Hence, there exists a supreme purpose that bestows meaning upon all that exists—God.

In exploring the problem of existence, Thomas Aquinas draws upon Aristotelian teachings and the Christian doctrine of the creation of the world as a whole and the individual entities within it, by God, through the act of His will.

Following Severinus Boethius (circa 480-524), Thomas Aquinas develops the doctrine of essence and existence—one of the foundational concepts in Catholic religious philosophy. According to this doctrine, essence, or "pure idea," of an object or phenomenon is a composite of certain characteristics (properties, traits) that exist in the mind of God (as God's design). Existence is, in essence, the very fact of an object's being. For any given essence to attain existence, it must be involved in being; more simply put, it must be created by divine will.

Thus, any object (phenomenon, process, etc.) is an essence that has gained existence as a result of divine volition. God, who grants an essence potential existence, may also revoke such capability. Therefore, the world is not constant in its substantial manifestations. The world as a whole, and each individual thing within it, is in a state of perpetual change. The only unchanging entity is God Himself, in whom essence and existence coincide, being identical to one another.

Distinguishing, in accordance with Aristotle, between actual and potential states, Thomas considers being to be the first of the actual states. In any thing, the degree of being corresponds to the degree of actuality it possesses. Accordingly, he identifies four levels of the beingness of things (depending on the degree of their actuality, which is expressed in the manner by which form—i.e., the actualizing principle—manifests itself in things).

At the lowest level, form, according to Thomas, constitutes merely the external determination of a thing; this includes inorganic elements and minerals (inanimate nature). At the next tier, form emerges as the final cause of a thing, which thus possesses a purpose; this is referred to by Aristotle as the "vegetative soul," which seemingly shapes the body from within—such are plants. The third level pertains to animals; here, form acts as an efficient cause, such that being encompasses not only a goal but also the inception of activity and motion.

At all three levels, form is variably combined with matter (entering into matter), organizing and animating it. Finally, at the fourth level, form appears no longer as an organizing principle of matter but as a self-sufficient entity, independent of matter. This is spirit or reason, the rational soul. Unbound by matter, the human rational soul does not perish with the death of the body. Thus, the rational soul is termed "the self-subsistent" by Thomas. In contrast, the sensitive souls of animals are not self-subsistent; therefore, they lack actions unique to the rational soul, which occur solely through the soul, independently of the body—such as thought and will. All actions of animals, much like many actions of humans (aside from thought and acts of will), are carried out through the body. Thus, animal souls perish with the body, while the human soul is immortal, representing the noblest aspect of creation.

In following Aristotle, Thomas regards reason as the highest of human virtues, perceiving in will, first and foremost, its rational determination, which he believes to be the ability to distinguish good from evil. Like Aristotle, Thomas sees in will a practical reason—reason oriented toward action rather than knowledge, guiding our deeds and our conduct in life, rather than theoretical contemplation.

In Thomas's world, true entities are ultimately individuals, humans. This distinctive form of personalism defines the specificity of Thomistic ontology (the philosophical doctrine of being). Beginning with God, who is the pure act of being, and concluding with the least of created essences, each entity is endowed with relative autonomy, which diminishes with the movement downward, i.e., with the reduction of the actuality of beings placed on the hierarchical ladder.

Thus, according to the philosophy of being articulated by Thomas Aquinas, all objects in the world represent a unity of matter and form (idea). Here, form (idea) emerges as the determining principle, while matter is merely subsumed within this form. Form (idea) simultaneously serves as the purpose for which God creates the object. The idea (the form of the object) is always tripartite: it exists in the divine mind, within the object itself, and in human perception (its memory).

Regarding the doctrine of humanity, every human (person) is a union of soul and body. The soul is immaterial and non-substantial, achieving its completeness only through its conjunction with the body. For Thomas Aquinas, human personality is the noblest within all rational nature. The meaning of human life is love of God.

Thomas's teachings were profoundly influential during the Middle Ages, and the Roman Church recognized Aquinas as a saint. His doctrines experienced a revival in the twentieth century under the name "Neothomism," becoming one of the most influential currents in Catholic philosophy in the West.

The principal works of Thomas Aquinas include the "Summa Theologiae" and the "Summa Philosophica" (on the truths of Catholic faith against pagans).

Thus, scholasticism represents a religious-philosophical worldview characterized by the subordination of philosophy to theology, merging dogmatic propositions with rational and logical justification.