95. The Second Way: Per Se and Per Accidens in Motion

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Lecture Notes

Main Topics #

• The Second Way of Aquinas: An argument based on the distinction between per se and per accidens truth
• Per Se vs. Per Accidens: Whether a statement is necessarily true (per se) or contingently true (per accidens)
• The Problem of the Infinite Regress: Why an infinite series of movers and moved things is impossible
• Moved Movers (Middle Movers): Things that move other things while themselves being moved
• Principal vs. Instrumental Movers: The distinction between the chief mover and tools used by the mover
• Logical Terminology: Clarification of terms like propositio (premise), protasis (Greek), and terminus (term)

Key Arguments #

The Second Way: Per Se and Per Accidens #

• The Proposition: “Every mover is moved”
• Two Possibilities: This statement is either true per se or per accidens
• If per accidens: It is contingent, not necessary—meaning it could be false that anything is moved
  • But Aristotle holds that motion always was and always will be (necessary fact)
  • Therefore, this cannot be how the statement is true
• If per se: The mover must be moved by the same kind of motion, or contradictions follow
  • Example: A teacher would be taught the same science they teach (contradiction)
  • Or movers would be moved by different kinds of motion, leading to infinite regress through different species
• Conclusion: There must be a first mover not moved by another

The Middle Mover Argument (Expanded) #

• Definition of Middle Mover: Something that moves other things because it is itself moved by something else
• Key Principle: A middle mover cannot function as a mover without something before it
• The Problem of Infinite Series:
  • An infinite series of middle movers functions like one grand middle mover
  • The number of intermediate movers (one or infinite) makes no difference
  • But a middle mover requires a principal mover before it
  • Therefore, there must be an unmoved mover
• Logical Insight: A middle thing, by definition, requires something before and after it; a middle mover with nothing before it is a contradiction in terms

The Tool (Instrumental Mover) Argument #

• Definition: An instrumental mover is a tool—something that moves only when used by a principal mover
• Key Principle: A tool cannot move unless it is being used
• Infinite Regress Problem: An infinite series would consist only of tools with no user
• Conclusion: There must be a principal mover that is not itself a tool

Important Definitions #

• Per se (διὰ αὑτοῦ): Through itself; something that belongs to a thing by its very nature or definition; necessarily true
• Per accidens: By accident; something that belongs to a thing contingently, not through its nature; not necessarily true
• Propositio: Originally meaning the premise in a syllogism; Latin propositio, Greek πρότασις (protasis) from προτείνω (proteinō), meaning “to stretch forward”
• Moved Mover (Media Moventia): Something that moves other things while itself being moved by something else; also called a “middle mover”
• Middle Mover: A mover that has something before it (what moves it) and something after it (what it moves)
• Unmoved Mover: Something that moves other things without itself being moved by anything external
• Principal Mover: The primary agent that moves; the one who uses tools
• Instrumental Mover: A tool or means used by a principal mover to achieve an end

Examples & Illustrations #

The Train Example #

• Setup: A locomotive pulls a boxcar, which pulls a caboose
• Key Insight:
  • The locomotive is the unmoved mover (principal mover)
  • The boxcar is a moved mover—it pulls only because it is pulled by the locomotive
  • The caboose is purely moved (patient)
• Critical Point: If you remove the locomotive, the boxcar cannot pull the caboose
• Infinite Series Problem: Whether there is one intermediate car or infinitely many, they function as one grand moved mover—and still require the locomotive
• Application: An infinite chain of intermediate movers without a first unmoved mover can move nothing

The Chandelier/Chain Example #

• Setup: A lamp hangs from a chain of links attached to the ceiling
• Structure: Each link is a “held-up holder”—it holds the link below because it is held by the link above
• Critical Problem: If the chain extended infinitely into the sky with no attachment to the ceiling, it would hold nothing
• Key Insight: The number of intermediate links (whether one or infinite) makes no difference—there must be something that holds without being held (attached to the ceiling/beam)
• Application: The same principle applies to any series of dependent movers

The Chain of Desire (from Aristotle’s Nicomachean Ethics) #

• Scenario: A is desired for the sake of B; B is desired for the sake of C; and so on infinitely
• Problem: An infinite chain of means (things desired only as means to something else) presupposes an end, but there would be no end
• Resolution: There must be some ultimate good that is desired for its own sake, not as a means to something else
• Generalization: This principle applies to all causes, not just efficient causes

Historical Note: Dewey’s Campaign Train #

• Anecdote about President Thomas Dewey speaking from the back platform of a campaign train
• An engineer’s action caused the train to jerk, illustrating unexpected consequences
• Used conversationally, not philosophically

Questions Addressed #

Q: Can a statement be true per accidens in the context of the divine motion argument? A: No. If “every mover is moved” were true per accidens (contingently), it would be possible that nothing is moved. But Aristotle holds that motion always was and will be (a necessary fact). Therefore, the statement cannot be true per accidens.

Q: What does it mean for a mover to be moved “per se” (through itself)? A: If a statement is true per se, it follows from the very definition or nature of the thing. If “every mover is moved” is true per se, then the same mover must be moved by the same kind of motion, leading to contradiction (e.g., a teacher being taught the same science).

Q: Why does the number of intermediate movers not matter? A: Whether there is one intermediate mover or infinitely many, they function as one grand moved mover. Since a moved mover requires something to move it, an infinite series cannot escape the need for a first unmoved mover.

Q: How is a “middle mover” defined? A: A middle mover is something that has something before it (what moves it) and something after it (what it moves). This is the logical definition of “middle”—what comes after something and before something else. A middle mover cannot function without something before it.

Q: What is the difference between a principal mover and an instrumental mover? A: A principal mover is the agent that uses other things to achieve its end. An instrumental mover is a tool—something that moves only when used by a principal mover. An infinite series of tools with no principal mover to use them accomplishes nothing.

Q: Do students need actual knowledge of the ultimate end (happiness) for the chain-of-desire argument to work? A: Not explicit knowledge. The student noted that one must have the end “in a confused way.” The will’s object is the good, which must be known by reason, but this knowledge need not be explicit or complete.

Linguistic and Logical Clarifications #

On the word “Propositio” (Latin) / “Protasis” (Greek)

• Originally propositio meant a premise in a syllogism, not simply a statement
• The Latin pro-positio means “placed before” or “stretched forward”
• The Greek πρότασις (protasis) from προτείνω (proteinō) carries the sense of “stretching forward,” more precisely capturing the logical function
• Medieval usage sometimes conflates the statement with the premise, but the original meaning emphasizes the premise’s role in an argument

On the word “Terminus” (Latin) / “Term” (English)

• In modern English, “term” has become confused with “word”
• Strictly, terminus in logic means the end-points of a syllogism’s resolution
• When Aristotle analyzes a syllogism, he breaks it into three terms (major, minor, and middle)
• The expression “define your terms” is influenced by this logical usage, but really means “define your words”
• Berquist notes this is a curious way the usage of logic has influenced daily speech

On the word “Proportion” (Latin) / “Proportio”

• Proportio originally means “analogy” or “relative correspondence”
• In usage, it came to mean “ratio” (the relationship between two quantities)
• This shift in meaning is a common historical change in terminology
• Berquist dislikes this usage shift but acknowledges it is now customary