The Philosophy of Knowledge of Thomas Aquinas (Thomas of Aquinas)June 26, 2021
According to Thomas Aquinas, “philosophy aims at knowledge of the true existence and essential nature of things, rather than empirical knowledge of the physical world obtained through controlled observation and measurement.”
In Aristotelian philosophy, substance is used in two different senses. The first of these is united with matter, and the other is form in a simple sense. Here, the substance, which points to a compound structure in its first sense, is the object at the target of human knowledge. Man is a composite structure made up of body and soul. It is logical that the objects that are the subject of his knowing activity are also in a compound structure. If we look at it from another angle, the object of human cognition is objects in motion.
According to Thomas Aquinas, “if the mind did not have knowledge of material things, we would not have any (descriptive) knowledge of them, and hence we would not be able to speak of a natural science dealing with material things subject to change.” (Sum. Theol., Ia, q. 84, art. I, Sed Contra). What is meant here is the understanding that also influenced Platonic thought. According to this understanding, since everything is constantly changing, it is not possible to obtain information from the variable itself. Thomas Aquinas therefore feels the need to emphasize Heraclitus’ approach that the water of the flowing river cannot be touched twice (“non est possibile aquam şüvii currentis bis tangere”).
According to the Heraclitus understanding, since everything is in a state of becoming, it is not possible to say anything definite about anything. We know that Kratylos clings to this approach, even going a little further, not talking about anything, and trying to answer questions by simply moving his finger.
According to him, the Heraclitus doctrine, which states that there is no certainty in the knowledge obtained through the senses, is wrong. According to Thomas Aquinas, the reason for this attitude of Kratylos is simple. Before Kratylos had finished his statement about anything, he believed that the fact that the statement pointed to had changed and therefore his statement had no meaning in reality. A simple finger gesture, however, was much shorter than the time required to verbalize the expression. According to Aquinas, Cratylos was doing something even worse than Heraclitus in this sense. Because, according to Heraclitus, it was impossible to touch a flowing river a second time; because the water you touched before would have already gone down. However, according to Kratylos, it was not possible to touch the river even once. Because the water you wanted to touch would have been replaced by another water before you touched it.
According to Thomas Aquinas, since the objects in this physical world are in a constant state of change, it is impossible to make judgments about them by staying within the limits of sense knowledge alone. This understanding is an aspect of Platonic teaching that deserves respect. Just as Boethius did, Thomas Aquinas here also states that it is not the property of the known that reveals the truth in propositions about physical existence; but he states that he is the knower.
It is within the Augustinian Platonic tradition, which advocates the priority of a soul that uses the body in sensation. According to this approach, which is expressed in philosophy as “nauta in navi = sailor using the ship”, only the soul is sufficient for a person to realize his competence.
It should be said here that knowing is the most important condition of existence. Knowing is a mental activity, and according to Thomas Aquinas, man is a man only as long as he is rational. Rationality is the human act of understanding and making judgments. The starting point in the knowing process of the human being, who needs the mental soul to make judgments, that is, to reveal information about a situation using concepts, is the particular physical object. According to Thomas Aquinas, corporeal objects have an effect on the sense organs. Since the place where this effect arises is the human body, which is a composite structure, sensation (sensatio) also appears as a composite act. This compound structure consists of the soul and the body, as we have mentioned before. Our senses, by their very nature, perceive particular objects. The objects of the human mind are universal structures. The human mind reveals its action through the universal forms it abstracts from particular physical objects. What man grasps through sensation is each individual object itself. That tree, that pen, that table are individual insights that we get as a result of our senses. In addition to this, there are also images of these physical individual existences. When we close our eyes and think of Ahmet or Ayşe, we realize an individual understanding.
Prepared by: Sociologist Ömer YILDIRIM
Source: Omer YILDIRIM’s Personal Lecture Notes. Atatürk University Sociology Department 1st Year “Introduction to Philosophy” and 2nd, 3rd, 4th Grade “History of Philosophy” Lecture Notes (Ömer YILDIRIM); Open Education Philosophy Textbook