St. Thomas Aquinas, the well-known Italian philosopher and theologian, revalued Aristotle’s opinions and principles regarding the human soul’s immortality. The latter believed in an eternal soul that perishes after the cease of the body. On the contrary, Aquinas sees a soul as an immortal spiritual being connected to the body forming a human substance. According to him, the soul’s spiritual functionality makes it capable of performing without the matter (Jensen 2018). It means that the soul, as a composite of the body, can also exist without matter. Soul has metaphysical features to remain alive without the capability to act. In other words, St. Thomas believes that the human soul is capable of an operation per se immaterial; thus, it cannot be corrupted. In his work Summa Theologiae, the philosopher provides two significant arguments to support this premise, one of which will be further explained.
Aquinas argues that men use intellect to acquire knowledge of all corporeal things. In Summa Theologiae I, q. 75, a. 2, he states that the knowledge about certain things is not embedded into someone’s nature because it would impede the knowledge of anything else. In other words, the mind is immaterial because it does not contain the nature of the body. He makes an example of a sick man’s tongue that is unable to sense anything sweet because of bitter humor and feverish. The same occurs when one wears colored spectacles and decreases the eyes’ ability to receive accurate information regarding the color of the objects, simply unable to distinguish them (McCabe 1969, 303). Both examples indicate that biased sensory organs limit human perceptions of certain things. Consequently, if the human intellect was dependent on biased material organs, it could not grasp certain corporeal things. Instead, the human mind can perceive many different things not relying on body organs.
According to Feser (2009), this argument should be interpreted so that intellect has distinctive potencies that make possible learning forms of other things without losing its own form. The mind grasps the same and one form that exists in the things themselves (Feser 2009). For instance, if someone thinks about triangles, the mind recalls the actual form of triangularity. If the intellect was a material thing, the form of the triangle may be materially stored in the brain, becoming its integral part. Whenever someone thinks about any figures, the part of the brain would transform into these figures.
Moreover, the parcel of matter that composes it would cease to be an intellect and would never understand other things. It is also not possible to think about two different objects and take on their forms simultaneously since nothing can become two different things at the same time. Since such an assumption leads to absurdity, the intellect should be considered immaterial. It explains the thought presented by St. Thomas that knowledge about one thing “would impede the knowledge of anything else” if the mind was material (Feser 2009). In reality, intellect can take on multiple forms within a short period grasping different natures. It means that the intellectual principle subsists and able to operate per se apart from the body. Similarly, McCabe (1969) agrees that the mind is beyond the physical nature since nobody is able to possess the nature of all objects or creatures. The intellect makes it possible to understand the nature of other things without being this particular thing.
To conclude, Aquinas made two arguments in favor of the premise that the human soul is capable of an operation that cannot be effected through the body. This essay explains his first argument that intellect (soul) is subsistent and incorporeal. It is capable of grasping all forms of material things and can operate per se. Even if the material sensitive organs are damaged and biased, the human mind can grasp multiple things. The idea of the soul’s materiality leads to physical absurdity; thus, intellect is not corporeal and able to understand things without transforming its own parcels of matter.
Aquinas, Thomas. 2018. Summa Theologica. Claremont: Coyote Canyon Press.
Feser, Edward. 2009. Aquinas. Oxford: Oneworld Publications.
Jensen, Steven. 2018. The Human Person: A Beginner’s Thomistic Psychology. Washington, D.C.: Catholic University of America Press.
McCabe, Herbert. 1969. “The Immortality of the Soul: The Traditional Argument.” In Aquinas: A Collection of Critical Essays, edited by Anthony Kenny, 297-306. London: Palgrave Macmillan.