55. Nature, Motion, and the Study of Natural Philosophy

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Lecture Notes

Main Topics #

Nature, Motion, and Natural Philosophy #

• Nature (φύσις/physis) is defined as the principle or source of motion and change
• Since natural philosophy is about things that are by nature, and nature is fundamentally defined by motion, understanding nature requires understanding motion distinctly
• Without distinct knowledge of motion, we cannot have distinct knowledge of nature

Three Aspects of “Natural Hearing” (Φυσικὴ Ἀκρόασις/Physikē Akroasis) #

Berquist explains why Aristotle’s work is called Natural Hearing rather than Physics:

1. Content: We are “hearing about” natural things
2. Method: We listen to nature as a student listens to his teacher, not as a judge interrogates a witness
   • The student receives the teacher’s full discourse
   • The judge/lawyer constrains the witness to specific questions (like the experimental method)
   • Natural philosophy prioritizes receptive listening; experimental science prioritizes directed questioning
3. Epistemic Stance: We listen “with and through what is naturally known” — approaching nature through our natural understanding

Two Reasons to Study Motion, Place, Time, and the Unlimited Together #

Reason 1 (Causal Connection):

• Motion is intrinsically connected to place (especially local motion), time (all motion takes time), and the continuous/unlimited (motion involves continuous change)
• These concepts cannot be separated; understanding motion requires understanding all three

Reason 2 (Universality):

• Place and time are common to all natural things
• Everything that exists naturally exists somewhere and at some time
• Since natural philosophy studies things in general, these universal properties must be examined

The Problem of Defining Motion #

Modern Objections:

• Descartes claims motion cannot be defined because:

  • We are already certain about motion
  • Defining it would require clarity and distinctness that we lack
  • To him, definition is impossible for things we already understand

• Implicit in Locke’s empiricism: Motion is a “simple idea” that cannot be defined; only composite ideas admit definition

The Fundamental Misunderstanding:

• Both Descartes and Locke assume that not everything can be defined—but this principle is Aristotelian, not modern
• Descartes confuses certainty with clarity and distinctness:
  • We may be certain of something while knowing it confusedly (not clearly and distinctly)
  • Example: We know for certain there is a difference between men and women, but cannot state it precisely
  • Certainty does not entail clarity or distinctness

The Regress Problem and Limits of Definition #

Why Not Everything Can Be Defined:

• If every statement required proof from other statements, we could never begin to know anything (infinite regress)
• Some statements must be self-evident or known through themselves
• Examples of self-evident truths:
  • “A whole is greater than a part”
  • “No odd number is even”
  • These are known immediately once their terms are understood

The Principle Applied to Definition:

• Just as not everything requires proof, not everything requires definition
• We must learn basic terms by associating sounds with sensible objects (not through other words)
• Only after grasping basic concepts can we define more complex ones
• This is how children learn language; this is how philosophy must begin

Key Arguments #

Aristotle’s Reasoning for Studying These Four Topics #

1. Natural philosophy is about things defined by motion
2. Therefore, we must study motion distinctly
3. Motion is connected to place, time, and the continuous
4. Therefore, we must study these together
5. Additionally, place and time are universal to all natural things
6. Therefore, since we study nature in general, these universal properties must be examined

Against Descartes’ Claim That Motion Cannot Be Defined #

1. Descartes confuses certainty with clarity/distinctness
2. We can be certain about something while understanding it confusedly
3. The principle “not everything can be defined” is Aristotelian, not a modern discovery
4. The question is not whether motion can be defined, but where definition must begin
5. Motion can indeed be defined because it is always “the motion of something else” (never self-subsisting), providing multiplicity necessary for definition

Important Definitions #

Nature (Physis/φύσις): The internal principle or source of motion and change in a thing; that from which motion originates

The Continuous (τὸ συνεχές/to synechés): That which is infinitely divisible; what admits division into parts without end

The Unlimited (ἄπειρον/apeiron): That which has no boundary or limit; first appears in the continuous

Natural Hearing (Φυσικὴ Ἀκρόασις/Physikē Akroasis): The study of nature through listening to nature as a student listens to a teacher, as opposed to interrogating nature through directed experiment

Examples & Illustrations #

The Method of Learning: Student vs. Judge #

• The Student: Receives the teacher’s complete discourse; listens to everything the teacher presents
• The Judge/Lawyer: Constrains the witness to answer specific questions only; does not allow free testimony
• Berquist’s Application: Natural philosophy begins like the student listening; experimental science proceeds like the judge questioning
• Distinction from Kant: Kant argued we must learn from nature as judge learns from witness; Berquist argues we should learn both ways, beginning with the student’s approach

The Mind’s Unlimited Character #

• The mind can know universals that cover infinite particulars (odd numbers, even numbers, “something” itself)
• The mind can continue counting indefinitely (children amazed at counting to 100, then 1,000)
• The mind invents continuously: automobiles, airplanes, computers—each new design exceeds the previous
• Contrast with animals: Bees build hexagonal hives identically to how they did in Greek times; insects do one or two things perfectly but are lost outside that; animals do not innovate
• Language shows this infinity: Unlike animal groans and meows (limited), human language has infinite expressive power
• Even saying “I don’t know everything” presupposes openness to “everything”

East Meets West: The Principle of Opposites #

• Aristotle: Found that all his predecessors reasoned about change through contraries/opposites—“forced on our mind by truth itself”
• The I Ching (Book of Changes): Eastern philosophy, unknown to Aristotle, based entirely on yin and yang (contraries/opposites)
• Newton: “For every action, there is an equal and opposite reaction”
• Modern Physics: Atoms explained by contrary forces (nuclear forces holding protons together against centrifugal forces); relativity and quantum mechanics built on fundamental contraries
• Conclusion: This principle appears universally across civilizations and times, suggesting it is something we naturally think rather than freely hypothesize

The Definition of Nature as Matter and Form #

• Students begin with Aristotle’s definition of nature confusedly
• Through study, they understand how nature is both matter and form
• This understanding becomes more distinct as they see how matter and form relate to change and becoming
• The definition remains the same, but knowledge of it deepens

Comparison with the Nicomachean Ethics Method #

• Book I (Ethics): Aristotle defines happiness initially using the word “virtue” (ἀρετή/aretē)
• Later Books: Must investigate human virtue in detail to understand the definition more clearly
• Book X: Returns to the definition of happiness with deeper understanding of virtue
• Parallel Structure: The definition of nature uses “motion”; deeper understanding of motion clarifies the definition of nature

Notable Quotes #

“Since nature is the beginning of motion and change, and the road we are following is about nature, what motion is ought not to be hidden from us. For this being unknown, necessarily nature is unknown.” — Aristotle, Physics III.1 (cited by Berquist)

“Wisdom is to speak the truth and to act in accord with nature, giving ear thereto.” — Heraclitus (cited by Berquist as exemplifying the proper stance toward nature)

“Our reason learns from nature, but not in the way a student learns from his teacher. Our reason learns from nature in the way a judge or lawyer learns from a witness.” — Immanuel Kant, Critique of Pure Reason, Preface to the Second Edition (Kant’s claim about experimental science; Berquist argues both methods are needed)

“Custom is a tyrant.” — Shakespeare (on how custom closes the mind, as Berquist notes in discussing how people resist learning new ways of understanding)

“The definition of the continuous is that the continuous is what is divisible forever.” — Aristotle, Physics VI (cited by Berquist regarding infinite divisibility)

Questions Addressed #

Q: Why cannot Descartes define motion if we are certain about it? A: Descartes confuses certainty with clarity and distinctness. We may be certain about something while understanding it confusedly. Aristotle already established that not everything requires—or should receive—a definition. The question is where the process of definition begins, not whether definition is possible.

Q: How can motion be defined if it always has parts (which are themselves motions)? A: Motion can be defined not through its parts but through its relationship to something else: motion is always the motion of something else. It is never self-subsisting. This relational character provides the multiplicity necessary for definition. Unlike a point (which is simple and cannot be defined through parts), motion has this inherent complexity.

Q: Why study motion, place, and time together rather than separately? A: They are intrinsically connected through motion. Motion requires place (especially in local motion), takes time (all motion occurs through time), and involves the continuous (which appears first in the continuous). Additionally, place and time are universal properties of all natural things. The two reasons—causal connection and universality—make simultaneous study necessary.

Q: What is the difference between the student’s learning and the judge’s interrogation? A: The student receives the teacher’s complete presentation and listens to everything. The judge constrains the witness to answer only specific questions. In natural philosophy, we should initially learn from nature as a student learns from a teacher, receiving nature’s full revelation. Later, we may adopt the judge’s method (as in experimental science) to answer particular questions.

Connections to Course Structure #

• Book III of the Physics: This lecture introduces the third book’s focus on motion as central to natural philosophy
• Book VI of the Physics: Later treatment of the continuous (τὸ συνεχές) and the unlimited (ἄπειρον) will be more detailed
• Book IV of the Physics: Will address place and time in greater detail
• Definition of Nature: Recalls the earlier definition and shows why understanding motion is essential to grasping it
• Teleology Arguments: The earlier arguments for nature acting for an end depend on understanding motion correctly