32. The Three Principles of Change: Substance and Contraries

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Lecture Notes

Main Topics #

• Three Principles of Change: Aristotle’s argument that explaining change requires not just two contraries but a third thing—the underlying subject that persists through change
• The Apparent Contradiction: How Aristotle argues both that contraries are accidents (not substances) and that substance must be a principle alongside the contraries
• Dialectical vs. Demonstrative Reasoning: Understanding that Aristotle proceeds from probable opinions rather than necessary demonstrations
• Principle of Fewness: Why three principles are sufficient and necessary—fewer is better only if sufficient to explain the phenomenon
• Substance as Fundamental: Substance is the first subject underlying all accidents and is more fundamental than contrary accidents

Key Arguments #

The Second and Third Arguments for a Third Thing (Beyond the Two Contraries) #

• From Substance’s Primacy: If contraries (which are accidents) are principles, then the substance underlying them must also be a principle, since substance is more fundamental than accidents
• From Impossibility of Non-Substance Becoming Substance: How can a substance (e.g., butter) arise from accidents (hardness, softness)? The underlying substance must be a principle
• The Necessity of an Underlying Subject: The subject must persist through change; it is the “in-between” nature capable of receiving contrary accidents

Arguments Against More Than Three Principles #

• Sufficiency Argument: Two contraries and one underlying subject are sufficient to explain all change; a fourth thing would be unnecessary
• Substance as One Genus: Substance is the fundamental genus of being; in any one genus, there is only one pair of contraries (the species furthest apart)
• Application of Principle of Fewness: No necessity forces us beyond three principles; therefore, three suffice

Important Definitions #

Substance (οὐσία / ousia) #

• A thing that exists not in another subject; it stands under and underlies all accidents
• Examples: man, dog, animal
• The first subject underlying all accidents
• Etymology: Latin substare (to stand under); understanding (English) derives from the same root because reason (mind) knows substance while senses know only accidents

Accident #

• A thing that exists in another subject and cannot exist apart from it
• Examples: health, sickness, hardness, softness, color, shape, knowledge
• Depends on substance for existence; cannot be separated from the substance (e.g., health cannot exist in one room while the person exists in another)

Contraries #

• Opposite qualities in the same genus that can affect the same subject
• In any genus, contraries are the species that are furthest apart
• Examples: health and sickness, hard and soft, white and black, virtue and vice
• Cannot exist in substance (there are no contrary substances); only in accidents

Examples & Illustrations #

The Butter Example #

• Hard butter becoming soft: The butter (substance) persists while losing hardness (one contrary) and acquiring softness (opposite contrary)
• Why a third thing is necessary: Hardness cannot directly become softness without contradiction; the butter is neither hardness nor softness but capable of both
• Contrast with substance: A man cannot become a horse; there are no contrary substances

Color and Habit as Genera of Accidents #

• Color genus: White and black are contraries (furthest apart species); yellow and blue are intermediate colors. Only one pair of contraries exists in this genus
• Habit genus: Virtue and vice are contraries; continence and incontinence are intermediate states. Only one pair of contraries in this genus
• Demonstrates that in any single genus, only one pair of contraries exists

Virtue and Vice in the Soul #

• Virtuous person: Will and emotions aligned toward good; no conflict
• Vicious person: Will and emotions both directed toward evil; no conflict
• Continent person: Will directed toward good while emotions pull toward evil; internal struggle
• Incontinent person: Reason/conscience resisting while will directed toward evil
• The soul (substance) persists as the subject capable of receiving contrary states

The Christmas Cookie Analogy #

• One idea (form) of a Christmas tree shape
• Multiple pieces of dough (matter) can receive this one form
• Illustrates how multiplicity can be understood from the perspective of matter or form

Questions Addressed #

The Central Apparent Contradiction #

Problem: How can Aristotle argue both that:

1. Contraries are accidents (not substances), so substance must also be a principle
2. Substance is one genus with only one pair of contraries (implying contraries exist in substance)?

Key to Resolution: Aristotle proceeds dialectically from probable opinions, not demonstratively. Both statements contain partial truth:

• True aspect of “no contraries in substance”: There are no contrary species in substance (man is not contrary to stone)
• True aspect of “contraries in substance”: There are contrary differences in substance (rational vs. irrational)

Why Three Principles Are Necessary #

Problem: Why can’t change be explained by just the two contraries?

Answer: Because contraries cannot directly become each other. There must be a third thing—the subject—that is neither contrary but capable of receiving both. The subject is what persists through change.

Why Not More Than Three? #

Problem: Why stop at three principles?

Answer: Because three are sufficient to explain all change. Adding a fourth principle would require additional contraries, creating unnecessary multiplication. The principle of fewness applies: fewer principles are better if they suffice.