102. Interior Senses and Animal Cognition

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Lecture Notes

Main Topics #

The Four Interior Sense Powers #

Thomas Aquinas distinguishes four interior powers of the sensitive soul, following and critiquing Avicenna’s five-power scheme:

1. Common Sense (Sensus Communis): Receives all sensations from the five exterior senses and serves as their central terminus; judges between objects of different senses (distinguishing white from sweet); perceives the act of sensing itself.

2. Imagination (Phantasia/Imaginatio): Retains sensible forms (colors, sounds, tastes) after the object is absent; serves as a “treasure” or repository of received forms.

3. Estimative Power (Vis Aestimativa): Perceives intentions—non-sensible qualities that the exterior senses cannot grasp, such as whether something is useful, harmful, or suitable to the animal (e.g., a sheep recognizing a wolf as an enemy through instinct rather than sensory pain).

4. Memory (Vis Memorativa): Retains the intentions perceived by the estimative power; in animals, memory is sudden recall of what is past; in humans, it involves reminiscence through a quasi-syllogistic process.

The Principle of Reception and Retention #

Thomas employs a metaphysical principle from natural philosophy: in bodily things, what receives forms easily does not retain them well, while what retains well receives with difficulty (the moist receives but does not retain; the dry retains but receives with difficulty). This principle justifies distinguishing the common sense (which receives sensations immediately) from imagination (which retains them).

Distinction Between Human and Animal Powers #

In animals, the estimative power operates by natural instinct alone; memory is involuntary recall of the past.

In humans, two crucial differences emerge:

• The cogitative power (particular reason/ratio particularis) replaces the estimative power, bringing together individual intentions through reasoning rather than instinct alone.
• Reminiscence replaces mere memory; humans deliberately inquire into the past through a quasi-syllogistic process, using remembered facts as premises to reconstruct absent moments.

These differences reflect the influence of universal reason upon the sensitive powers in humans, elevating them beyond mere animal instinct.

Avicenna’s Fifth Power and Thomas’s Rejection #

Avicenna posits a fifth interior power that combines and divides imaginative forms—what we might call “creative imagination.” Examples include composing an image of a “golden mountain” from the separate images of gold and mountain. Thomas argues this operation is adequately explained by the ordinary imaginative power under the influence of universal reason (the intellect); no fifth distinct power is necessary.

Key Arguments #

Why Interior Powers Are Necessary #

Objection: The exterior senses and their common sense suffice for all sensory knowledge; interior powers add nothing necessary.

Response: Perfect animals require knowledge not only when objects are present but also in their absence. This enables animals to pursue absent goods and flee absent harms. Since bodily powers cannot both receive and retain excellently, distinct powers are required: the common sense receives, imagination retains.

The Estimative Power and Non-Sensible Perception #

Objection: If exterior senses suffice for judgment and memory, why posit an estimative power that perceives intentions not known by sense?

Response: Animals perceive things as harmful, useful, or suitable—intentions not given in sensation as such. A young bird crouches from a predator without sensory experience of harm; a sheep flees a wolf through natural instinct, not because the wolf’s color or shape is painful. These demonstrate a power beyond sense perception.

Why Cogitative Power Differs from Estimative Power in Humans #

In animals: The estimative power grasps intentions automatically and immediately through natural instinct.

In humans: The cogitative (particular reason) grasps the same intentions but through a kind of reasoning—a bringing together (colatio) of particulars. This quasi-syllogistic process is evident in reminiscence: reconstructing “where was I at 4 PM last Friday?” by recalling what happened at 8:30 AM, then 10:00 AM, then after lunch, etc., working methodically to recover the absent moment.

Important Definitions #

• Intention (intentio): A non-sensible quality perceived by the estimative or cogitative power—what is useful, harmful, past, or suitable to an animal; not perceived by the exterior senses as such.

• Cogitative Power (Vis Cogitativa) / Particular Reason (Ratio Particularis): In humans, the power that grasps individual intentions through reasoning, bringing together particular facts to make judgments or recover memories. Operates with the influence of universal reason.

• Reminiscence (Reminiscentia): Deliberate recall of the past through a quasi-syllogistic process; unique to humans; involves reasoning from remembered premises to reconstruct absent moments.

• Common Sense (Sensus Communis): Not common by predication (said of all senses) but common as a source (like a center from which all radii extend); the central power to which exterior sensations are referred.

• Natural Instinct: The way non-rational animals perceive intentions; immediate, unreasoned, and inherited through nature rather than experience.

Examples & Illustrations #

The Estimative Power in Animals #

Kitten and Belts: A kitten plays fearlessly with various belts but becomes terrified of one particular belt with bands. It has not been harmed by this belt but perceives it as an enemy through the estimative power. An older cat would not be fooled.

Bird Collecting Straw: A bird gathers straw for nesting not because straw delights the senses but because the bird perceives straw as useful for building—an intention grasped without sensory experience.

Sheep and Wolf: A sheep flees a wolf through natural instinct, perceiving the wolf as harmful to its nature, not because the wolf’s sensory qualities (color, shape) are disagreeable to sensation.

Reminiscence in Humans #

Reconstructing the Past: When asked “Where were you at 4 PM last Friday?” one cannot recall directly but reasons backward: “I had an 8:30 class, then a 10:00 class, then I went to the library, then I met Joe at 3 o’clock…” Through this quasi-syllogistic inquiry, one works toward the desired moment.

Remembering a Name: Trying to recall someone’s name, one thinks through contexts: “Where do I know that guy?” and methodically reconstructs situations until the name returns—a reasoning process, not a mere involuntary memory.

Questions Addressed #

Must interior powers be posited if exterior senses and common sense suffice? #

Resolution: No. Perfect animals must act toward absent goods and away from absent harms. This requires retaining sensations when objects are absent—a function the common sense (which receives only in presence) cannot perform. Thus imagination is necessary. Further, animals perceive intentions (harmfulness, usefulness) not given in sensible qualities, requiring the estimative power.

How does human cognition of particulars differ from animal instinct? #

Resolution: In animals, the estimative power grasps intentions through natural instinct—immediately and without reasoning. In humans, the cogitative power grasps the same intentions but through colatio (bringing together), a quasi-reasoning process influenced by universal reason. This is why humans can deliberately remember through reminiscence, while animals recall suddenly and involuntarily.