49. The Four Causes and Their Applications in Definition

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Lecture Notes

Main Topics #

The Structure of Definition and Its Causes #

• Definitions must contain only what belongs to the thing defined, yet defining relational or dependent things requires introducing other things into the definition
• Example: A point (the end of a line) cannot be defined without reference to a line; health (a disposition of the body) cannot be defined without reference to body
• The principle: genus corresponds to the material aspect of a thing; differences correspond to the formal aspect
• In substance, definition is found primarily; in accidents, definition is secondary and must reference what the accident inheres in

Which Causes Appear in Which Sciences #

• Different sciences examine different causes; not every science requires all four causes
• In geometry: only the formal cause is typically examined (e.g., why angles formed by intersecting straight lines are equal is because the lines are straight)
• Geometry does not ask about final causes or why it is good that angles be equal
• The selection of which causes to examine is determined by the nature of the subject matter

The Number of Causes in Definitions #

• Some things require only one cause in their definition (geometry example)
• Some require two or three causes
• Some require all four causes
• The number depends on the nature of the thing being defined

Key Arguments #

The Aristotelian Principle of Causes in Definition #

• A definition drawn from a thing’s causes properly reflects what that thing is
• When Aristotle discusses the four causes in metaphysics, he asks which causes are relevant to the subject being examined
• The causes one includes in a definition should match the nature of the thing defined

The Primacy of Final Cause (Where It Exists) #

• The final cause, when it is a cause, is the cause of the other causes being causes
• This gives the final cause special importance even when all four causes are present in a definition

Important Definitions #

Matter and Form in Definition #

• The material aspect of a thing (its parts or what it is composed of) corresponds to the genus in definition
• The formal aspect of a thing (what actualizes or distinguishes it) corresponds to the differences in definition
• These are not identical to matter and form in the metaphysical sense, but correspond to them

Examples & Illustrations #

The Point as the End of a Line #

• A point cannot be defined without referencing a line
• Yet the definition properly captures what a point is by showing its dependence on line
• This illustrates how even limit or terminal entities require reference to what they limit

Health #

• Cannot be defined simply as health; must be defined as “a good disposition of the body” or similar
• Health is not the same as body (the body can be healthy or sick), yet health cannot be understood without reference to body
• Demonstrates that accidental forms require reference to their subjects

Marriage: “The Stable Union of a Man and a Woman by Mutual Choice for the Sake of Children” #

• Formal Cause (Form): The stable union; the unity and wholeness
• Material Cause (Matter): A man and a woman; the parts
• Efficient Cause (Mover): Mutual choice; what brings the union into being
• Final Cause (End): Children; the purpose
• All four causes are present in a complete definition of marriage

Sacrament: “An Outward Sign Instituted by Christ to Give Grace” #

• Efficient Cause (Mover): “Instituted by Christ”
• Final Cause (End): “To give grace”
• Material and Formal Causes (implicit): Distinguished in sacramental theology as the sensible matter (water in baptism) and the form (the words: “I baptize you in the name of the Father, the Son, the Holy Spirit”)
• Thomas speaks of these as matter and form of the sacrament
• The four causes are all involved, though not all are equally explicit in the catechetical definition

Geometry: Intersecting Straight Lines #

• When straight lines intersect, the angles formed are equal
• Why? Because the lines intersecting are straight (formal cause)
• The proof relies on the axiom that when a straight line meets a straight line, the angles equal two right angles
• If the lines were bent or curved, the equality would not hold
• Geometry does not ask about final cause: e.g., “a geometric sphere is round so it can roll out of danger” (this would be absurd)

The City or Nation #

• Material Cause: The citizens
• Formal Cause: The order and arrangement of the city
• Efficient Cause: The founder (George for a nation)
• Final Cause: The purpose, which differs in an oligarchy and a democracy
• All four causes must be examined to understand what a city or nation is

The Church #

• Material Cause: Members of the church
• Formal Cause: The order and hierarchy (up to the Pope)
• Efficient Cause: The founder (Christ)
• Final Cause: The purpose of the church
• As one studies more deeply, one sees all four causes involved

God as a Cause #

• When speaking of God as a cause, fewer causes may be directly invoked
• God is typically understood as the Exemplary Cause (the form or pattern of all things)
• God is the Efficient Cause (the maker; the mover)
• God is the Final Cause (the end toward which all things tend)
• Material cause does not apply to God
• The exemplary and efficient causes tend to run together, as God causes things to be like Himself

Notable Quotes #

“So I bring something other than point into the definition of point, right? Because point is something of another. And so to define it, I have to say what it is, and of what it is, what it is.”

(Illustrating how dependent or relational things require reference to other things in their definitions)

“In defining a substance you have genus and differences, right? This corresponds to the fact that intrinsically it’s composed of matter and form. See? Not that genus is the same as matter, or difference is the same as form, but genus is taken more from what is material in the thing, huh? And difference is what is more formal in the thing.”

(Explaining the correlation between logical and metaphysical structure)

“So you might have just one of the four causes, right? And you might have as many as, what? All four, right?”

(Establishing that the number of causes in a definition varies by the nature of the thing)

Questions Addressed #

How Many Causes Should a Definition Contain? #

• Answer: It depends on the nature of the thing being defined and the science examining it. Geometry may involve only formal cause; other sciences require all four causes. There is no universal rule—the science must determine which causes are relevant to understanding the thing.

How Do We Recognize Which Causes Belong in a Definition? #

• Answer: By understanding the nature of the thing itself. If something is a substance composed of matter and form (like a human being or a marriage), all four causes should be examined. If something is a limit or formal relationship (like a point in geometry), fewer causes may be required.

Why Does a Definition Sometimes Seem to Require What Is “Other Than” the Thing Itself? #

• Answer: Because some things are essentially relational or dependent. A point is essentially the limit of a line; to say what a point is requires reference to line. This is not a defect in definition but a reflection of the thing’s actual nature.