20. God Not in a Genus: Article 5 on Divine Simplicity
Summary
This lecture covers Thomas Aquinas’s fifth article proving God is not contained in any genus, systematically eliminating the composition of genus and difference. Berquist explains the distinction between being in a genus ‘simply and properly’ (as a species) versus ‘by reduction’ (as a principle), then demonstrates through three arguments why God cannot be a species of any genus. The lecture emphasizes how understanding the Isagoge and Aristotelian logic is essential for grasping why God has no genus, no differences, and therefore no definition.
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Lecture Notes
Main Topics #
The Structure of Article 5 #
- Part of the systematic elimination of six kinds of composition in God
- Follows articles eliminating: quantitative composition, matter-form, essence-individual, essence-existence
- This article eliminates composition of genus and difference
- Directly related to showing God is not in any genus and therefore has no definition
Two Ways of Being in a Genus #
- Simply and Properly (simpliciter et proprie): As a species contained under the genus
- Example: Dog is in the genus Animal
- By Reduction (per reductionem): As a principle or privation of the genus
- Example: Soul (principle of substance), Point (beginning of continuous quantity), One (beginning of discrete quantity)
- Example: Blindness (privation of the quality vision)
The Distinction Between Points and Ones #
- Similarity: Both are indivisible and beginnings
- Key Difference in Ratios:
- One can have to a number the same ratio that a number has to a number: 1:2 = 2:4 = 3:6
- A point cannot have to a line the same ratio that a line has to a line
- Therefore, one is closer to being a number than a point is to being a quantity
- Mathematical Evidence: Line is not composed of points, but number is composed of ones
- Euclid’s Theorem: In the theorem about numbers in the least ratio, Euclid must extend the word ’number’ to include one—an analogous (not purely equivocal) use
Key Arguments #
First Argument: Species Constituted from Genus and Difference #
- Species is constituted from genus and difference
- The “wherefore” of difference always stands to the “wherefore” of genus as act to potency
- Porphyry notes: genus is to difference as matter is to form
- Examples of act-potency relationship in genus-difference:
- Animal (sensitive nature) to Rational (intellectual nature): intellectual is to sensitive as act to potency
- Each case of genus and difference manifests this relationship
- Conclusion: Since God is pure act with no potency, He cannot be a species in any genus
Second Argument: Being Cannot Be a Genus #
- God’s being is His essence (proven in Article 4)
- If God were in some genus, that genus would have to be Being
- But Aristotle shows in Book III of the Metaphysics that being cannot be a genus
- Reason: Every genus has differences outside the nature of the genus, but no difference can be found outside being
- Non-being cannot be a difference (difference must be something)
- Conclusion: God is not in the genus of substance or any other genus
Third Argument: Being vs. Existence in Genera #
- All things in one genus share the nature/essence of that genus (predicated as “what it is”)
- But they differ in their being/existence: the being of man ≠ the being of horse, the being of this man ≠ the being of that man
- Principle: Whatever things are in a genus must differ in their existence while sharing a common nature
- In God: existence and nature are identical (no difference)
- Conclusion: God is not in a genus as a species
On God Not Being in a Genus by Reduction #
- The beginning that is reduced to a genus does not extend beyond that genus
- Point: beginning only of continuous quantity
- One: beginning only of discrete quantity (number)
- God is the beginning of all being (as will be shown below)
- Conclusion: God is not in a genus even by reduction as a principle
Important Definitions #
Genus (γένος / genus) #
- From Logic: “The name predicated of many things differing in kind, or in species, in answer to the question ‘what is it?’”
- Signifies the essence or nature of a thing
- In Aristotle’s framework, substance is the first and primary genus
Species (εἶδος / species) #
- A particular kind of thing placed under a genus
- The genus is predicated of the species in answer to the question “what is it?”
- Examples: Dog under Animal; Virtue under Habit; Justice under Virtue
Difference (διαφορά / differentia) #
- The distinguishing feature that determines how a genus is divided into species
- Always stands to genus as act to potency
- Cannot be predicated in answer to “what is it?” but rather indicates how the thing is
Substance (οὐσία / substantia) #
- First sense (Aristotle’s proper usage): An essence to which belongs the property of existing in itself, not in another
- Distinguished from accident, which exists in another
- In the notion of substance: a distinction between the thing (its nature) and its being
- God cannot be in the genus of substance because God’s nature and existence are identical
Predicament (praedicamentum) #
- Latin for the ten highest genera (categories of Aristotle)
- From the English development: “predicament” now means a difficult situation from which there is no escape
- Philosophical parallel: Once something is in a genus (predicament), it cannot escape to another category
- Example: Man (substance) cannot become a quality instead
Examples & Illustrations #
The Soul in the Genus of Substance #
- Question: Is the soul a substance, or a part of a substance, or a principle of a substance?
- Answer: The soul is a principle of a substance
- Nevertheless: The soul is reduced back to the genus substance (even though not “simply and properly” a substance)
- Distinction: A principle differs from a species but shares in the genus through reduction
Blindness and Privation #
- Blindness is a privation of sight
- Reduced to the genus Quality (as the lack of a quality)
- Not “simply and properly” a quality but by reduction as a privation
Point as Beginning of Continuous Quantity #
- Point is the beginning of a line
- A line is a species of continuous quantity
- Is the point itself a quantity? No
- Yet it is reduced to the genus of quantity as its principle
- Unlike quantity, a point has no parts
The One and Number #
- Is one itself a number? No
- Yet one can have to two the same ratio that two has to four (1:2 = 2:4)
- This shows one is closer to number than a point is to quantity
- In contrast: A point cannot have to a line the same ratio that a line has to a line
- Therefore: One is more like a number (as a beginning) than point is like quantity
Shakespeare’s Understanding of One and Number #
- The Phoenix and the Turtle: “Love has made the lover and the loved one”
- “Therefore it’s murdered number”
- Shakespeare’s insight: Understands that one is not itself a number
- Personal example: “I don’t have a number of wives, as I tell my students. Or a number of heads. I have a number of arms, a number of legs, because two is the first number.”
Triangle in General vs. Particular Triangles #
- Universal concept of triangle: open to equilateral, scalene, and isosceles
- The universal is not actually any one of these but is able to be all of them
- Analogy: Like wood that can be made into a chair, table, or door
- Wood is not actually any of these until it receives its form
- Problem with Locke and Anaxagoras: Both struggle with the notion that genus must contain all its differences virtually
- Anaxagoras: puts everything in matter, causing logical problems
- Locke: makes the universal idea of triangle all or none of the particular triangles
Implications for Theology #
Why God Has No Definition #
- Definition is composed of genus and difference
- God is not in any genus
- God has no differences
- Therefore: God has no definition (definitio)
- Consequence: There is no demonstration (demonstratio) of God (in the Aristotelian sense)
- Because the middle term in a demonstration is a definition
- And definition depends on understanding what genus a thing belongs to
The Reply to the First Objection #
- Objection: Substance means “existing by itself” (ens per se), which belongs most to God; therefore God is in the genus substance
- Thomas’s Reply: The term “substance” signifies not only existing by itself, but rather an essence to which it belongs to exist in this way
- That is, a thing whose nature is such that it has this kind of being (in itself, not in another)
- But being itself cannot be a genus
- Therefore, God is not in the genus of substance
The Key Distinction in Substance #
- In creatures: There is a distinction between the nature of a thing and the existence it has
- In God: Nature and existence are identical
- Conclusion: The notion of substance as a category requires this distinction; since God lacks it, God is not in any genus
- In the Summa Contra Gentiles: More explicitly developed—substance is “a thing whose nature belongs to it not to exist in another”
Questions Addressed #
Why doesn’t Thomas have a separate question eliminating God as a universal whole? #
- In the discussion of wholes (composed vs. universal), the question arises why Thomas doesn’t explicitly ask about God and universal wholes
- Answer: This is implicitly addressed in the question on God’s unity (where it is shown there is only one God, not many gods)
- Thus both kinds of wholes are eliminated: no composed whole (Article 3-4), and no universal whole (shown when proving God is one)
How does understanding the Isagoge relate to this article? #
- Central to the lecture: Understanding Article 5 requires knowledge of:
- What genus is
- What species is
- What difference is
- Porphyry’s distinctions (the predicables)
- Berquist laments: “Most philosophers I run into now have not read the Isagogi. And some of them have not even heard of it.”
- Without the Isagogi: One cannot understand why God is not in a genus
- The name: Isagogi is Greek (Εἰσαγωγή) meaning “introduction” (Latin: introductio)
- The text is an introduction to the Categories of Aristotle but useful for understanding predication universally