Hylomorphism and the Soul: Aristotle & Thomas on Immortality

Doctrine of the Soul: Hylomorphism and Immortality

Doctrine of the Soul

Both Aristotle and St. Thomas rejected Platonic dualism that identifies a human being with the soul alone. Aristotle, in his theory of hylomorphism, held that soul and body are united as form and matter; for St. Thomas Aquinas, this union does not invalidate the claim that the soul is immortal.

The soul is the substantial form of the body, the principle of life and organization. It is therefore also the principle of human operations, which are diverse. St. Thomas treats these operations as various faculties or active powers in the soul, each responsible for certain activities.

Division of Powers

These powers are subdivided into lower powers (those common to animals) and higher powers proper to humans. In broad categories:

• Lower powers — sensory and common operations shared with animals.
• Cognitive powers — powers related to knowledge, both sensible and rational.
• Appetitive powers — appetites and desires connected with the will and passions.

There are also distinctions within cognitive faculties: some operations depend on the senses, others on intellectual understanding. Their natures are very different, even when they cooperate.

Hylomorphism and Immortality

According to St. Thomas, hylomorphism is compatible with the immortality of the human soul if one considers that forms are not necessarily corrupted in the same way as material composites. Some powers are fully actualized in the embodied subject, while others retain a kind of potency or operation that is not exhausted by bodily existence. To the extent that an intellectual power transcends its corresponding bodily limit, it is capable of knowing in a non-material way; if it clearly transcends bodily limitations, it can understand in an immaterial manner. This is the basis for the claim that the human soul can be immortal, a conclusion reached from analysis of the soul's operations and intelligibility.

Dependence on Body and the Intellect

St. Thomas maintains that cognitive operations can rely on the senses and on intellect, although these capacities are essentially different. Some powers of the soul depend intrinsically on particular bodily organs and therefore cannot remain once those organs are destroyed. In addition, some powers are limited in their objects because the nature of the senses is limited compared with the intellect's capacity to receive forms.

By contrast, the intellect (understanding) can grasp the forms of many kinds of things. For Aristotle, the soul is the locus of forms; the intellect is characterized by not being restricted to a specific set or type of thing. This does not mean it understands everything at once, but that the intellect is capable of understanding more and more and is not confined to a single sensible domain.

Therefore, the intellect is not intrinsically dependent on a particular body. While intellectual activity depends on the brain accidentally (that is, in practice the brain is required for embodied cognition), the intellect is not identical with any bodily organ. One may say that the mind uses the body, but the mind is not the body; if the intellect were merely bodily, its capacity would be limited like the senses and it could not know universal forms.

This leads to the conclusion that if the intellect can operate in a manner not essentially tied to any bodily organ, then it can survive the destruction of the body. In short, the union of soul and body in hylomorphism is consistent with the claim—developed by Aristotle and articulated by St. Thomas—that the human intellect has a mode of operation that supports the possibility of the soul's immortality.