Thomism
Thomism is the philosophical and theological school which arose as a legacy of the work and thought of Thomas Aquinas, the Dominican philosopher, theologian, and Doctor of the Church.
In philosophy, Thomas's disputed questions and commentaries on Aristotle are perhaps his best-known works. In theology, his Summa Theologica is amongst the most influential documents in medieval theology and continues to be the central point of reference for the philosophy and theology of the Catholic Church. In the 1914 motu proprio Doctoris Angelici, Pope Pius X cautioned that the teachings of the Church cannot be understood without the basic philosophical underpinnings of Thomas's major theses:
Overview
held and practiced the principle that truth is to be accepted no matter where it is found. His doctrines drew from Greek, Roman, Islamic and Jewish philosophers. Specifically, he was a realist. He often affirmed Aristotle's views with independent arguments, and largely followed Aristotelian terminology and metaphysics. He wrote comprehensive commentaries on Aristotle, and respectfully referred to him simply as "the Philosopher".He also adhered to some neoplatonic principles, for example that "it is absolutely true that there is first something which is essentially being and essentially good, which we call God, everything can be called good and a being, inasmuch as it participates in it by way of a certain assimilation".
Metaphysics
Aquinas says that the fundamental axioms of ontology are the principle of non-contradiction and the principle of causality. Therefore, any being that does not contradict these two laws could theoretically exist, even if said being were incorporeal.Predication
Aquinas noted three forms of descriptive language when predicating: univocal, analogical, and equivocal.- Univocality is the use of a descriptor in the same sense when applied to two objects or groups of objects. For instance, when the word "milk" is applied both to milk produced by cows and by any other female mammal.
- Analogy occurs when a descriptor changes some but not all of its meaning. For example, the word "healthy" is analogical in that it applies both to a person or animal which enjoys good health and to some food or drink which promotes health.
- Equivocation is the complete change in meaning of the descriptor and is an informal fallacy, for example when the word "bank" is applied to river banks and financial banks. Modern philosophers call it ambiguity.
Being
In Thomist philosophy, the definition of a being is "that which is", a principle with two parts: "that which" refers to its quiddity, and "is" refers to its esse. Quiddity means an essence, form, or nature which may or may not exist; whereas esse refers to existence or reality. That is, a being is "an essence that exists."Being is divided in two ways: that which is in itself, and that which is in another. Substances are things which exist per se or in their own right. Accidents are qualities that apply to other things, such as shape or color: "ccidents must include in their definition a subject which is outside their genus." Because they only exist in other things, Aquinas holds that metaphysics is primarily the study of substances, as they are the primary mode of being.
The Catholic Encyclopedia pinpoints Aquinas' definition of quiddity as "that which is expressed by its definition." The quiddity or form of a thing is what makes the object what it is: "hrough the form, which is the actuality of matter, matter becomes something actual and something individual", and also, "the form causes matter to be." Thus, it consists of two parts: "prime matter", and substantial form, which is what causes a substance to have its characteristics. For instance, an animal can be said to be a being whose matter is its body, and whose soul is its substantial form. Together, these constitute its quiddity/essence.
All real things have the transcendental properties of being: oneness, truth, goodness, etc.
Causality
Aristotle categorized causality into four subsets in the Metaphysics, which is an integral part of Thomism:Unlike many ancient Greeks, who thought that an infinite regress of causality is possible, Aquinas argues that an infinite chain never accomplishes its objective and is thus impossible. Hence, a first cause is necessary for the existence of anything to be possible. Further, the First Cause must continuously be in action, otherwise the series collapses:
Thus, both Aristotle and Aquinas conclude that there must be an uncaused Primary Mover, because an infinite regress is impossible.
However, the First Cause does not necessarily have to be temporally the first. Thus, the question of whether or not the universe can be imagined as eternal was fiercely debated in the Middle Ages. The University of Paris's condemnation of 1270 denounced the belief that the world is eternal. Aquinas' intellectual rival, Bonaventure, held that the temporality of the universe is demonstrable by reason. Aquinas' position was that the temporality of the world is an article of faith, and not demonstrable by reason; one could reasonably conclude either that the universe is temporal or that it is eternal.
Goodness
As per the Nicomachean Ethics of Aristotle, Aquinas defines "the good" as what all things strive for. E.g., a cutting knife is said to be good if it is effective at its function, cutting. As all things have a function/final cause, all real things are good. Consequently, evil is nothing but privatio boni, or "lack of good", as Augustine of Hippo defined it.Commentating on the aforementioned, Aquinas says that "there is no problem from the fact that some men desire evil. For they desire evil only under the aspect of good, that is, insofar as they think it good. Hence their intention primarily aims at the good and only incidentally touches on the evil."
As God is the ultimate end of all things, God is by essence goodness itself. Furthermore, since love is "to wish the good of another", true love in Thomism is to lead another to God. Hence why John the Evangelist says, "Whoever is without love does not know God, for God is love."
Existence of God
Thomas Aquinas holds that the existence of God can be demonstrated by reason, a view that is taught by the Catholic Church. The quinque viae found in the Summa Theologica are five possible ways of demonstrating the existence of God, which today are categorized as:Despite this, Aquinas also thought that sacred mysteries such as the Trinity could only be obtained through revelation; though these truths cannot contradict reason:
Aquinas responds to the problem of evil by saying that God allows evil to exist so that good may come of it, but does not personally cause evil Himself.
View of God
Aquinas articulated and defended, both as a philosopher and a theologian, the orthodox Christian view of God. God is the sole being whose existence is the same as His essence: "what subsists in God is His existence." Consequently, God cannot be a body, He cannot have any accidents, and He must be simple. Further, He is goodness itself, perfect, infinite, omnipotent, omniscient, happiness itself, knowledge itself, love itself, omnipresent, immutable, and eternal. Summing up these properties, Aquinas offers the term actus purus.Aquinas held that not only does God have knowledge of everything, but that God has "the most perfect knowledge", and that it is also true to say that God "is" His understanding.
Aquinas also understands God as the transcendent cause of the universe, the "first Cause of all things, exceeding all things caused by Him", the source of all creaturely being and the cause of every other cause. Consequently, God's causality is not like the causality of any other causes, because He is the transcendent source of all being, causing and sustaining every other existing thing at every instant. Consequently, God's causality is never in competition with the causality of creatures; rather, God even causes some things through the causality of creatures.
Aquinas was an advocate of the "analogical way", which says that because God is infinite, people can only speak of God by analogy, for some of the aspects of the divine nature are hidden and others revealed to finite human minds. Thomist philosophy holds that we can know about God through his creation, but only in an analogous manner. For instance, we can speak of God's goodness only by understanding that goodness as applied to humans is similar to, but not identical with, the goodness of God. Further, he argues that sacred scripture employs figurative language: "Now it is natural to man to attain to intellectual truths through sensible objects, because all our knowledge originates from sense. Hence in Holy Writ, spiritual truths are fittingly taught under the likeness of material things."
In order to demonstrate God's creative power, Aquinas says: "If a being participates, to a certain degree, in an 'accident,' this accidental property must have been communicated to it by a cause which possesses it essentially. Thus iron becomes incandescent by the action of fire. Now, God is His own power which subsists by itself. The being which subsists by itself is necessarily one."