Soul
Soul
For Aquinas, after Aristotle, the soul is the actualizing principle of all living things. The question of the soul’s existence and immortality trouble modern minds; even the word “soul” today has been replaced by many modern philosophers with the word “mind,” to mean the brain. Aristotle thought of body and soul as united as matter and form. But this was problematic for anyone who believed that forms whose purpose was to animate the body could survive after the body’s demise. The soul’s essence, its powers, its immortality captivated Aquinas, ideas that present complex terrain.
Aquinas held that souls inhabit all living things, but they vary, depending on the beings they occupy. Aquinas called a plant soul nutritive and vegetative. As a matter of interest, his thoughts on the soul-nature of a human embryo was that as a zygote, the human’s soul was of a nutritive or vegetative state like a plant’s soul, therefore, at conception the embryo was not fully human, a direct contradiction of the teachings of the Catholic Church on abortion. He would, however, change his thinking in his writings on abortion in his work on ethics and the law in the Summa Theologica. Non-human animals can sense, so he called them ‘sensory.’ Humans can reason, so he called the human soul ‘rational.’ The human soul has the powers of will (choice) and intellect.
According to Aquinas, the nature of the human soul was comprised of substantial and of subsistent forms. The substantial form of the soul unites to the body, the two together constituting a human being. In its subsistent form, the soul has the power to exist apart from the body. How can the two exist at the same time, apart from and as part of the body? Resolving this contradiction was dicey, and it is considered one of Aquinas’ greatest intellectual achievements, the discussion of which continues further on.
Aquinas’ arguments for the physical nature of the soul, that the soul is a body, stems from his arguments on motion. The soul must have contact with the body if, indeed, the soul is the cause of the body’s movement. If the soul knows bodies, then it must be a body also. Just as in the scholastic disputations of the university, Aquinas made counter-arguments to the belief that the soul is a body.
Unlike Plato’s dualism, separating body and soul to speak of what it meant to be human, Aquinas insisted that the body is central to the concept of being human. Of course, soul alone can’t perform the functions required to be a human being. The soul does play a crucial role in the body’s functions. The specter, still, was Aquinas’ belief that the soul can exist apart from the body, yet to label him a dualist like Plato and Descartes would not be accurate. He was ingenious in devising a way for the body to be one with the soul, and separate from it. He maintained that after the body disintegrated, the body and soul must, therefore, be reunited. His ingenious solution of the resurrection of the body would have appalled Aristotle. After death, the soul would be able to identify the body from which it had separated.
For Aquinas the soul’s powers were will (appetite/desire) and intellect (rational). The two act interdependently, so in every voluntary action they are working together toward universal good. The intellect is a higher power than the will because its object is the nature of good things desired, while will desires the good things themselves. This begs the question of Aquinas: is it better to know than to love?
What of immortality? Aquinas reasoned that if humans showed such a strong desire to live, it must be in our essential nature to desire immortality. His arguments here, are influenced perhaps more by his Christian theology that affirms resurrection to eternal life through faith in Christ. As philosopher he had the conundrum of finding a way for the form of the soul to exist apart from the matter of the body. He did this by claiming the soul has form as simple (non-composite) and subsistent, so the soul has being in its own right. It can act on its own, and therefore exist on its own. While separated from the body, says Aquinas, the soul enters another mode of being. It takes on something like an angelic state, yet it is still inferior to angels. It can perform its activity without recourse to the brain. Apart from the body it cannot function perfectly.
To attain happiness the soul must reunite with the body, which happens only by grace; the body-soul being must be restored to right relationship with God. Here, both philosopher and theologian meet to rejoin the form of the soul with the matter of the body, and to resurrect the dead as Christ was resurrected to eternal life.