139. Whether the Soul Knows Bodies Through Understanding

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Lecture Notes

Main Topics #

The Central Question of Philosophy #

Berquist identifies the foundational philosophical question underlying all inquiry: Does truth require that the way we know be the way things are? This question determines whether philosophers answer affirmatively (Plato) or negatively (Aristotle), and affects all subsequent positions on metaphysics, epistemology, and the nature of the soul.

The Problem of Flux: Pre-Socratic Background #

Heraclitus claimed all reality is in continuous flux: “You cannot step twice into the same river.” Cratylus radicalized this: “You cannot step even once into the same river.” This created an epistemological crisis—if all things are constantly changing, how can we have certain knowledge? The ancient philosophers who believed only bodies exist concluded that no certain knowledge is possible, since bodies are always in flux.

Plato’s Solution: The Theory of Separated Forms #

Plato posited a realm of immaterial, eternal, unchanging entities (εἶδος/eidos, Latin species or forma) existing separately from material things. These forms provide stable objects for knowledge. The soul knows bodies not directly but through knowledge of these separated forms. While this preserves the possibility of certain knowledge, it introduces a problematic second world and disconnects knowledge from sensible reality.

Why Plato adopted this position:

• He found certain knowledge in mathematics and through Socratic definitions
• He believed the way we know must correspond to the way things are
• Our understanding grasps things universally and immutably, so these things must exist universally and immutably

Aristotle’s Critique of Plato #

Thomas presents Aristotle’s objections:

1. The separated forms are unnecessary: Introducing other beings to know the very things we seek to understand compounds the problem (analogy: if you cannot count people in a room, going to Yankee Stadium does not help)
2. The forms exclude knowledge of motion and matter: This undermines natural science, which properly studies mobile bodies
3. The forms differ in mode of being from sensible things: They cannot serve as adequate explanations for knowledge of the sensible world

The Principle: Quidquid Recipitur, Recipitur Secundum Modum Recipientis #

Translation: “Whatever is received is received according to the manner of the receiver.”

Core insight: The form of a thing known must exist in the knower, but not necessarily in the same mode as it exists in the thing itself.

Examples from sensible knowledge:

• A marble statue receives your shape as its own shape (materially)
• Your memory receives your shape as your shape (immaterially, universally)
• The eye receives color without gold; taste receives sweetness without whiteness
• A mirror receives color and shape in one way; the mind receives them in another

Application to intellectual knowledge:

• The soul receives material and changeable things immaterially and unchangingly
• This reception is genuine knowledge, not false knowledge
• The difference in mode does not entail falsity; it reveals something about the knower’s nature

Key Arguments #

Against Plato’s Separated Forms #

1. The soul seeks to know sensible, material bodies
2. Plato introduces separated, immaterial forms as the objects of knowledge
3. But these forms differ fundamentally in mode of being from sensible bodies
4. Therefore, knowing the forms does not explain how we know sensible bodies
5. Conclusion: The separated forms are unnecessary and misguided

For Intellectual Knowledge of Bodies #

1. We do have certain, reasoned knowledge about bodies (natural science exists)
2. If the soul could not know bodies through understanding, natural science would perish
3. Therefore, the soul must know bodies through understanding
4. The mode of this knowledge is immaterial and universal, not material and singular

Resolving the Three Objections #

Objection 1 (Augustine): Bodies cannot be comprehended by understanding, only by senses

• Response: Augustine speaks of imaginary vision (images of bodies), not the soul’s direct knowledge. The soul forms likenesses and gives them something of its substance as a subject, but this does not mean the soul is changed into these images.

Objection 2: Just as sense cannot know immaterial things, understanding cannot know material things

• Response: Senses are particular knowing powers; understanding is universal. A higher power extends to what a lower power cannot reach, in a more excellent way. God and angels know bodies despite being immaterial.

Objection 3: Understanding knows only necessary, unchanging things; bodies are changeable

• Response: All motion presupposes something immobile (substance in accidental change, matter in substantial change). Unchanging relations exist in changing things (e.g., “Whenever Socrates sits, he remains in one place” is eternally true). We have unchanging knowledge of changing things.

Important Definitions #

Species/Form (εἶδος/eidos) #

• In Plato: An eternal, unchanging, immaterial entity existing separately from material particulars
• In Aristotle/Thomas: The intelligible form or nature of a thing as it exists in the mind, abstracted from matter
• Greek eidos means “form that is seen” (related to aiden, “to see”)
• Latin species carries the same visual etymology
• English “idea” is a poor translation, as it suggests subjective thought rather than objective form

Immaterial Knowledge #

• Knowledge that grasps the universal nature of a thing apart from its material conditions
• Example: Understanding what a line is (its definition) without imagining any particular line
• The mind receives the form universally, not as a particular material instance

Intelligible Form (Forma Intelligibilis) #

• The form of a thing as it exists in the understanding
• Distinct from the sensible form (as it exists in matter) and the imaginary form (as it exists in imagination)

Examples & Illustrations #

The Plastic Shape-Sorting Box #

A children’s toy with round, triangular, and square holes and matching blocks. The child must fit the round block through the round hole. The shapes are truly known, yet the shape is not in the child’s mind in the same way it is in the block. This demonstrates genuine knowledge without identity of mode.

Reflection in the Eye #

When you look into someone’s eye, you see yourself reflected. But this reflection is not how we truly know the person. The mirror receives the shape materially and passively; the mind receives it immaterially and actively.

The Marble Statue #

When marble takes on a person’s shape, it loses its previous form—the shape becomes the marble’s shape. But when the mind receives a person’s shape, the mind retains its own nature. The shape exists in the mind as your shape, not as the mind’s shape.

Water, Hydrogen, Proton #

Historical discovery illustrates the order of knowledge versus the order of things:

• Order of discovery: Water → Hydrogen (named for generating water) → Proton (named for being first, though discovered last)
• Order of reality: Proton → Hydrogen → Water
• The order in our knowledge is often reversed from the order in reality

Berquist’s Classroom Demonstration #

Berquist walks in front of the class and asks, “Where is Berquist?” By the time he finishes the sentence, he is no longer in the same place. This illustrates Cratylus’s radicalization of Heraclitus—you cannot even point once to something, because it changes as you speak.

Notable Quotes #

“Whatever is received is received according to the manner of the receiver.” — Quidquid recipitur, recipitur secundum modum recipientis (fundamental principle of Thomas Aquinas’s epistemology)

“You cannot step twice into the same river.” — Heraclitus, on the flux of all things

“You cannot step even once into the same river.” — Cratylus, radicalizing Heraclitus to show the problem of even pointing to changing things

“Like is known by like.” — Ancient philosophical principle accepted by Plato and pre-Socratics

“The soul is in some way all things.” — Aristotle, De Anima III, interpreted by Thomas as meaning the soul is in potency to all intelligible things, not in act

Questions Addressed #

Does the soul know bodies through the understanding? #

Answer: Yes. The soul knows bodies through understanding by receiving their intelligible forms immaterially and universally, not through the bodies themselves or through material likenesses. This knowledge is genuine despite the difference in mode between how the form exists in the mind and how it exists in the thing.

How can the mind know material and changeable things with certainty? #

Answer: The mind knows material things through their universal and unchanging aspects. All change presupposes something unchanging (substance, matter, or unchanging relations). The mind grasps these unchanging aspects through universal knowledge.

Why did Plato posit separated forms? #

Answer: Plato believed that if knowledge is true, the way we know must correspond to the way things are (answering yes to the central question). Since our understanding grasps things universally and immutably, Plato concluded that things must exist universally and immutably in a separate realm.

Why is Plato’s theory of separated forms problematic? #

Answer: It introduces unnecessary entities that differ in mode of being from the things we seek to know. It also excludes knowledge of motion and matter, which are proper subjects of natural science. The separated forms do not explain our knowledge of sensible bodies.

How does the principle quidquid recipitur resolve the epistemological problem? #

Answer: This principle shows that the form of a thing can exist in the knower in a different mode than in the thing itself without introducing falsity. The mind can truly know material things by receiving them immaterially, just as the eye truly knows color without receiving the gold that is colored.

What does the soul’s immaterial reception of material forms tell us about the soul itself? #

Answer: It reveals that the soul must itself be immaterial and unchanging. The soul can receive material and changeable things immaterially and unchangingly only because its own nature is immaterial and unchanging. This hints at the soul’s immortality.