66. The Subsistence of Animal Souls and the Distinction Between Sensing and Understanding

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Lecture Notes

Main Topics #

Article 3: Are the Souls of Brute Animals Subsistent? #

The Platonic Error: Plato distinguished between understanding and sensing but incorrectly attributed both to an incorporeal principle. This led him to conclude that if the understanding soul is subsistent, the sensing soul must also be subsistent.

The Aristotelian Solution: Only understanding operates without bodily involvement. Sensing necessarily involves bodily change and cannot exist independently of matter. Therefore, animal souls are not subsistent.

The Nature of Sensing vs. Understanding #

Sensing involves bodily change:

• The sense organ undergoes physical alteration from its object
• Excessive sensibles corrupt the sense (bright light blinds; loud sound deafens)
• Sensory organs lose sensitivity through overuse or damage
• Anger, joy, and all passions involve bodily change
• The emotions (called such from the motion of the body) are corporeal operations

Understanding does not involve bodily change:

• Understanding the greatest intelligibles (God, angels) enhances understanding of lesser things
• No sensory organ exists for understanding; the intellect doesn’t receive understandables in a bodily organ
• Understanding is not subject to corruption by its object as senses are
• The principle: sensing is an operation of the composite (soul-body together); understanding is an operation of the soul alone

The Problem of Proportional Reasoning #

When saying “sense is to sensible as understanding is to understandable,” we must understand in what way they are alike:

• The likeness: Both initially exist in potency to their objects; both receive their objects
• The difference: Sensing receives sensibles with bodily change in a bodily organ; understanding receives understandables without bodily change and without a bodily organ
• The error: Assuming all likenesses are identical—this commits a fallacy in proportional reasoning

The Division of Soul and Species Difference #

Against the first objection (“man comes together with animals in genus, so why not similar souls?”):

• Some things pertain to genus; some to species
• The species difference is determined by the form
• Species differences do not require that every property be the same
• Man differs from other animals not just in genus but in species

The potessive whole: The understanding soul contains all powers of the sensitive and vegetative souls. The sensitive soul has some powers the vegetative has, but not all. Hierarchy: understanding soul > sensitive soul > vegetative soul.

The Third Objection: The Soul as Mover #

The argument: If the soul moves the body, it has an operation without the body, so it must be subsistent.

The response: The motive power is twofold:

1. The appetitive power (commanding motion): This involves emotions and passions, which are clearly bodily changes (anger, fear, hunger). When you pick up a cat frightened by a dog, you feel the bodily trembling.
2. The executive power (carrying out motion): This is obviously bodily—the members obey the appetite.

Conclusion: To move the body is not an act of the sensing soul without the body. The soul doesn’t move the body directly; emotions and passions move it, and these are bodily.

Truth Between Two Extremes #

Extreme 1: No soul is subsistent; the soul is merely the organization/harmony of the body (like Simmias in Plato’s Phaedo)

Extreme 2: All souls are subsistent, including those of animals and even plants (extended Platonism)

The Thomistic Mean: Only the human soul is subsistent because only it has an operation—understanding—that doesn’t require bodily involvement. The soul is a substantial form (not a complete substance like an angel), created when the body is ready for it. Therefore: the soul doesn’t exist before the body (because it’s naturally ordered to this body), but it does exist after the body (because it’s subsistent).

Key Arguments #

Argument 1: From Species Difference #

1. Man and animals share a genus but differ in species
2. Species difference is determined by form
3. The soul (the substantial form) is what makes the difference
4. Therefore, different souls can exist even among living things sharing a genus

Argument 2: From Sensing’s Corporeal Nature #

1. Sensing necessarily involves bodily change in the sense organ
2. Excessive sensibles corrupt the sense (evidence: bright light blinds)
3. All sensing operations manifest this bodily involvement
4. Therefore, sensing cannot be an operation of the soul alone
5. Since animal souls only sense (lacking understanding), animal souls have no operation by themselves
6. What has no operation by itself is not subsistent
7. Therefore, animal souls are not subsistent

Argument 3: From Contrast with Understanding #

1. Understanding the greatest intelligibles enhances understanding of lesser things
2. Sensing the strongest sensibles corrupts the sense organ
3. This difference shows understanding has no bodily organ, unlike sensing
4. Therefore, understanding is immaterial and the human soul is subsistent
5. But sensing is material and corporeal
6. Therefore, animal souls (which only sense) are not subsistent

Argument 4: Being and Operation #

1. “As each thing has being, so it has operation” (Agere sequitur esse)
2. If animal souls were subsistent, they would have an operation by themselves
3. But animal souls have no operation by themselves (all their operations involve the body)
4. Therefore, animal souls are not subsistent

Important Definitions #

Subsistent (subsistentia): Able to exist by itself, not dependent on another for existence. A thing is subsistent if it has an operation by itself, because only what actually exists can operate.

Substantial form: The form of a body that gives it its being and essential nature. Unlike an accidental form (which belongs to the subject before the accident is added), substantial form is act before matter is added. The soul is the substantial form of the body.

Potessive whole: A whole whose power is distributed among parts. The understanding soul contains all the powers of the sensitive and vegetative souls, but the vegetative soul contains only its own powers, not those of the sensitive soul.

Emotion (ἐμοτίον): Motion of the body. Emotions and passions (anger, fear, hunger, joy) are bodily because they involve observable changes: increased heartbeat, trembling, heat or cold, etc. These are operations of the composite (soul and body together).

The appetitive power (vis appetitiva): The power that commands motion. It is twofold: the sensitive appetite (commanding through emotion/passion) and the rational appetite or will (commanding through reason).

Species difference: What distinguishes one kind within a genus from another. In man, the species difference is rationality (determined by the understanding soul). This difference doesn’t mean other properties must differ; it means the principle of the essence differs.

Examples & Illustrations #

Sense Corruption and Wine Tasting #

Wine tasters avoid spicy foods because strong flavors corrupt the palate, making it unable to taste delicate wines. After tasting pepperoni pizza, one must drink strong wine (Chianti) rather than delicate wine (Sauvignon Blanc). At a wine tasting, they serve plain white bread to cleanse the mouth—not something potent. This shows that sense organs are diminished by excessive stimulation.

Understanding Enhancement Through Study #

When studying difficult theology (like the Trinity—a greatest intelligible), one’s understanding is enhanced. Upon returning to easier subjects, they seem elementary. The same occurs in mathematics: after studying solid geometry (more difficult), plain geometry seems effortless. Understanding the most intelligible things makes lesser things easier to grasp—the opposite of sense corruption.

Sensory Overuse and Occupational Damage #

Factory workers exposed to loud machinery (bang, bang, bang) lose hearing. Young people listening to rock bands, especially in one ear, suffer hearing damage that doctors observe. People who eat spicy foods regularly burn out their sense of taste more than women do. This illustrates how sense organs are physically damaged by intense stimulation.

Fear in a Cat #

When a cat is frightened by a dog and you pick it up, you can feel the bodily trembling and rapid heartbeat—the emotion is manifestly corporeal. This shows that emotions (which are the motive powers in animals) involve bodily change.

The Proportion Misunderstood #

Example: “Four is to six as two is to three.” Someone might say, “Both pairs are even-to-odd ratios, so the proportion holds there.” But that’s wrong. The likeness consists in the ratio itself: four is two-thirds of six, just as two is two-thirds of three. The even/odd characteristic is irrelevant to the proportion. This illustrates why one must understand how things are alike in a proportion, not just that they share some property.

Ancient Philosophers and Humility #

Pythagoras, discovering the Pythagorean theorem, was called wise. He refused: “Don’t call me wise; God alone is wise. Call me a lover of wisdom (philosophos).” Heraclitus said: “As an ape is to man, so man is to God.” Socrates, told by the Oracle he was wisest, realized this meant he alone knew that he didn’t know. All great Greek philosophers recognized God’s wisdom far surpasses human wisdom—natural humility before the divine.

The Slave Boy in Plato’s Meno #

Socrates shows a slave boy his mistake about geometry. The boy must have the humility to admit error, not defend it from pride. Philosophy requires this humility—admitting you were wrong rather than clinging to error.

Notable Quotes #

“As each thing has being, so it has operation” (Agere sequitur esse)

• The fundamental principle: a thing’s operations follow from its manner of being. If a soul has an operation by itself, it must subsist by itself.

“The senses receive the sensibles in a bodily organ; the understanding does not receive the understandables in a bodily organ.”

• The key distinction proving understanding is immaterial while sensing is material.

“Likeness is a dangerous thing; it’s a slippery thing.”

• Attributed to Plato. Warns that apparent similarities can mislead if one doesn’t understand how or in what way things are alike.

“Truth is in between two extremes.”

• Berquist’s recurring theme: between those who say no soul survives (the materialists) and those who say all souls survive (the Platonists), the truth is that only the rational soul survives because only it has an operation by itself.

“The soul doesn’t exist before the body, but it will exist after the body.”

• Explaining how the soul is both a substantial form (ordered to this body, so not created before it) and subsistent (able to exist after bodily death).

Questions Addressed #

Q: If sensing is similar to understanding, why isn’t the sensing soul subsistent like the understanding soul? #

A: The similarity is only proportional and limited. Both initially exist in potency to their objects. But sensing receives its object with bodily change in a bodily organ (as evidenced by sense corruption from excessive stimuli), while understanding receives its object without bodily change and without a bodily organ. Since all operations of animal souls are sensing operations, and sensing necessarily involves the body, animal souls have no operation by themselves and thus are not subsistent.

Q: How does the fact that the soul moves the body prove the soul is subsistent? #

A: It doesn’t. The motive power is twofold: (1) the appetitive power commanding motion (involving bodily emotions and passions), and (2) the executive power carrying out motion (obviously bodily—the limbs obey). Neither constitutes an operation of the soul by itself. The emotions (anger, fear, hunger) that move animals are clearly bodily, involving trembling, increased heartbeat, and other physical changes.

Q: If man shares genus with animals, shouldn’t our souls be similar to theirs? #

A: No. While man and animals share the genus “animal,” they differ in species. The species difference is determined by the form—the substantial form of the soul. Species differences do not require that all properties be identical. Man’s soul is substantially different from animal souls because it has understanding, an operation that animals’ souls do not have.

Q: Did ancient philosophers understand humility? #

A: Yes. Pythagoras refused to be called wise, calling himself instead a lover of wisdom. Heraclitus compared man to an ape relative to God. Socrates taught that admitting one’s ignorance is the beginning of wisdom. All the great Greek philosophers recognized that God’s wisdom infinitely surpasses human wisdom—a natural form of humility before the divine, distinct from but related to Christian humility.

Q: Can senses and understanding both operate without the body? #

A: No. The senses necessarily involve bodily change. Bright light blinds; loud sound deafens; strong flavors corrupt the taste. Understanding, by contrast, is enhanced by considering the greatest intelligibles. This proves understanding alone operates without bodily involvement, making the human soul (which understands) subsistent, while animal souls (which only sense) are not.