76. The Unity of the Intellect Against Averroism

Subscribe in Podcast App | Download Transcript

Lecture Notes

Main Topics #

• The Averroist Error: The false doctrine that one universal intellect separated from individual bodies serves all human beings
• The Diversity of Images Problem: How Averroes attempted to explain individual understanding through the multiplication of phantasms while maintaining one intellect
• The Principle of Proportionality: Establishing why particular causes produce particular effects, not universal ones
• Immaterial Substance and Individuation: Why immaterial substances cannot be multiplied in the same species except through proportionality to matter
• The Nature of Understanding: How the intellect abstracts universal forms from particular images, making understanding independent of individual phantasms

Key Arguments #

Against the Averroist Position #

• The Geometry Argument: When a student and teacher both understand Euclid’s first theorem (construction of an equilateral triangle), they think about the same thing. If they had one intellect but different images (one imagines the triangle in one way, another in a different way), there would still be only one understanding of what a triangle is—not two understandings. Therefore, diverse phantasms do not necessitate diverse understandings.

• The Multiple Circles Comparison: One man can imagine multiple circles of the same size and still have only one understanding of circularity. The diversity of imagined circles does not create multiple understandings of what a circle is. By analogy, many men with different images should be able to have one understanding if the intellect is one—but this leads to absurdity.

• The Mirror Analogy: Two mirrors can reflect the same face simultaneously, creating two images of one face. But these are two images, not two faces. If one intellect served all men, Socrates and Plato would not be two different men but one man appearing differently through different bodies—which is absurd.

• The Principality of the Intellect: The intellect has principality (supreme authority) over the other powers of the soul; the senses serve the intellect. If there were one intellect and many sensory powers (one per person), the result would be one chief agent with many instruments—not two distinct agents with one action, but rather one understanding with many individual operations, which contradicts the Averroist need to maintain individuality.

The Solution: Individual Souls Through Matter #

• Proportionality to Body: Although the intellect is immaterial, the soul is the substantial form of a particular body. The soul is proportioned to this body, not that one. Therefore, according to the multiplication of bodies through matter (which has part outside of part through quantity and position), there are many individual souls of one kind.

• The Nut and Bolt Analogy: Two bolts, though bolts of the same kind, are proportioned to different nuts. Even if separated from the nuts, the bolts remain distinct because they were formed for different nuts. Similarly, human souls remain distinct because each is proportioned to its own body, and this distinction persists even after the body’s death.

• The Principle of Being and Unity: Each thing has unity in the same measure that it has being. Since man has one being (shared with the body through the one soul), he has one soul. When the body is destroyed, the soul’s unity and being remain because the soul has an existence that is its own, not merely dependent on the body.

Important Definitions #

• Phantasm (phantasma): The sensible image or representation retained in the imagination after sensation. It is particular and material, existing in the imagination as a likeness of the external thing.

• Understandable Form (forma intelligibilis): The universal form abstracted from phantasms by the intellect. It is immaterial and represents what is common to many particular things. This is not the same as the phantasm—understanding requires abstraction from the conditions of individuality present in the image.

• Substantial Form (forma substantialis): That by which a thing is what it is and has its being. The soul is the substantial form of the body, not something added to it.

• Proportionality (proportionalitas): The relation of a soul to its body such that the multiplication of bodies according to matter entails a multiplication of souls of the same kind, even though each soul is immaterial.

Examples & Illustrations #

• Euclid I.1 (The Equilateral Triangle): Construct an equilateral triangle on a given straight line by taking each endpoint as the center of a circle with radius equal to the line, then connecting the intersection point to the endpoints. Both students and teacher understand this same theorem, proving they think about the same thing even with different imagined diagrams. The diversity of diagrams does not create diversity of understanding.

• The Two Circles: One man imagines two circles exactly alike. He has only one understanding of what a circle is, not two understandings, despite having two imagined circles. Therefore, if two men imagined circles and had one intellect serving both, they would have one understanding—but Socrates and Plato are clearly distinct men, so they must have distinct intellects.

• The Cookie Press (Dough Cutter): Grandma rolls out continuous dough and cuts cookies with a cutter. The same shape appears many times through the multiplication of matter. Similarly, the human form (soul and body) appears many times through the multiplication of matter, creating many individual humans of one kind.

• The One Stove, Many Pots of Water: When one stove heats multiple pots of water, the heat in the stove generates heat in the water. The heat is not transmitted as a single active form that moves from stove to pots. By contrast, when a teacher teaches a student, the knowledge of the teacher does not generate knowledge in the student the way heat generates heat. This false analogy was used by objectors to suggest that knowledge is transferred like an active form, implying one knowledge belongs to both teacher and student.

• Many Drawing One Ship (Rope Analogy): If many agents pull a ship by one rope, there are many agents but one action of pulling. This illustrates how diversity of agents does not require diversity of action. By contrast, if one carpenter uses one hammer to strike, there is one agent and one action. The intellect’s relationship to understanding is analogous to the latter case—if one intellect, then one understanding, which would make all men one.

• The Eye and Colors: Many people seeing the same color see it by different likenesses (reflections in different eyes). Yet they all see the same color. The diversity of sensible likenesses does not prevent the unity of what is sensed. Similarly, understanding should allow for one universal form to be grasped by many intellects if they were one.

Notable Quotes #

• “The scandal is that they should have tried to prove the existence of the external world.” — Berquist, introducing the Averroist error of assuming nothing known is outside the mind.

• “Thomas got some sense.” — Berquist, affirming Aquinas’s response to the Averroist position.

• “I’m trying to prove that I’m not you. And that I differ from you only by the clothing I’m wearing. Something entirely outside what I am.” — Berquist, explaining Thomas’s reductio ad absurdum of the Platonic-Averroist position.

• “Each thing in this way has unity, in which it has being.” — Aquinas/Berquist, stating the principle that unity and being are correlative.

• “He’s being like a poet, right? He’s making this up.” — Berquist, on Averroes’s attempt to explain how one intellect serves many men through diverse images.

• “How likely they err” (quam leviter errant). — Aquinas, on the Averroists’ fundamental mistake.

• “They speak as if wisdom began with them.” — Aquinas, criticizing the Averroists’ arrogance in claiming to have discovered truth that all others missed.

Questions Addressed #

Q: How can many men understand the same thing if each has a different image? #

A: The image is not the form of understanding; it is merely the material from which the intellect abstracts the universal form. One man can imagine multiple circles and have only one understanding of circularity. Similarly, many men with different images can grasp one universal form if the intellect is one—but then they would have one understanding numerically, not individually distinct understandings. Since Socrates and Plato are clearly distinct individuals with distinct understandings, each must have his own intellect.

Q: If one immaterial intellect served all men, how would individuality be preserved? #

A: It cannot be. If Socrates and Plato shared one intellect (a complete immaterial substance), they would not be two men but one man appearing in two bodies. The only difference between them would be external (like wearing different clothes), not internal (of their very being). This is absurd.

Q: Can diverse phantasms in different minds account for diverse understandings within one universal intellect? #

A: No. The diversity of phantasms cannot create diversity of understanding if the intellect is one, because understanding operates on the universal form abstracted from phantasms, not on the phantasms themselves. The intellect abstracts one intelligible form from diverse phantasms of the same kind (as one man understands stone from diverse images of stone). Therefore, diverse images do not produce diverse understandings in one intellect—they would produce one understanding, making all men one, which is contradictory.

Q: How do many individual souls exist if the soul is immaterial and immaterial substances cannot be multiplied in one species? #

A: The soul, though immaterial in its intellectual operation, is naturally the form of a particular body. It is proportioned to this body, not that one. Matter (which has part outside of part through quantity and position) provides the principle of individuation. Many souls of one species can exist because they are not complete immaterial substances like angels, but rather forms proportioned to different bodies. When bodies are destroyed, the souls remain multiplied in their being because each soul has its own existence, which it shares with the body but is not dependent upon it.

Historical Context #

Berquist emphasizes that Averroism was not a marginal error but a widespread heresy “over the place” in the medieval universities. Thomas wrote De Unitate Intellectus Contra Averroistas specifically to combat this position, which represented a fundamental misreading of Aristotle. The Averroists’ error stemmed from a Platonic confusion: thinking that because we know universally and immaterially, there must be one universal immaterial intellect—but Thomas shows this violates Aristotle’s own principles of causality and individuation.