Historical PeriodsGreek Hellenic: 500 – 300 BCEGreek Hellenistic: 300 - 50 Roman Empire: 1st C BCE – 476 CEEarly mid ages: 500 - 1000Byzantine empire: 4th C – 15th CIslamic Golden Age: 8th C – 13th CLate middle ages: 1000 - 1500Renaissance: 14th – 17th CScientific Revolution: 17th CEnlightenment: 18th CIndustrial revolution: 19th CModern period: 20th - ???

Aristotle’s Natural Philosophy

I. Life (384 – 322 BCE) and Works

Lyceum

II. The Origin of Natural PhilosophyIII. Metaphysics and EpistemologyIV. Aristotle’s Metaphysics and EpistemologyV. Aristotle’s CosmologyVI. MotionVII. BiologyVIII. Achievements

II. The Origins of Natural Philosophy

• Democracy, sophists

• Philosophy of knowledge

• Competition

• Greek Gods

• Prosperity, slave state

• Contact with other cultures

Why Greece?

The Circle

Parmenides(520 – 480)

• Being and not being

• All change is a logical impossibility

Zeno of Elea(490 – 430)

• Change of place (motion) is impossible (Zeno)

Zeno’s paradoxes

Significance:

• Everyone following Parmenides must address

• Led to questioning how we know what we know (epistemology)

• Led to a confrontation: logic versus the senses

A. The question of change

III. Metaphysics and Epistemology

B. The question of knowledge

Epistemology • the senses versus the intellect• senses unreliable

• auditory illusion

• Real truth through the exercise of reason aloneImportance: attention directed to reasoning, argumentation

C. The Question of the Stuff“ That of which all things consist, from which they first come and into which they are ultimately resolved … the element and origin of all things.” Aristotle

Thales (624 – 546 BCE)

1. Water

• Mechanistic• Deterministic

2. Atoms

Democritus(460 – 370 BCE)

3. Numbers: The Pythagoreans

Pythagoras(580 -500 BCE)

a2 + b2 = c2

Pythagorean theorem

Music of the spheres

Significance: application of mathematics to Nature

4. Earth, air, water, fire

Empedocles (490 -430)

Love Strife

solid, gas, liquid, energy

Dominant paradigm until 19th Century

Love and Strife Resolve quesitonOf change

• Forms are the true reality

•characteristics

• characteristics1. Eternal (Changeless)2. Incorporeal (No physical

body)3. True reality

1. Mathematician (geometer)2. Benevolent3. Rational 4. Not omnipotent: Only a creator

god

• Carpenter analogy

4. Templates for the sensible world

• Demiurge: the divine craftsman

D. Plato (427-348 BCE) 1. The Two Worlds: Sensible and Forms

2. Plato’s Stuff• Construction of the Cosmos based on geometric principles

• Earth, air, water, and fire not basic elements

• Made of five platonic (regular) solids

Tetrahedron = Fire

Octahedron = air

Icosahedron = water

Cube = earth

Dodecahedron = aether

• First three can change by rearrangement of equilateral triangles

For example: 2 tetrahedrons (fire) = 1 octahedron (air)

IV. Aristotle’s Metaphysics and Epistemology

A. Metaphysics: Plato versus Aristotle1. Plato: properties of physical things from the Forms (external)

2. Aristotle: physical is reality; internal properties = form and matter

• Form = properties (weight, color, etc)

• Matter = structure (substance)

B. Epistemology1. Start with

senses

2. Leads to knowledge

Example: observation of dogs

Common sense!

3. Induction leads to deduction

• Form and matter cannot be separated

C. Nature and Change1. Change happens

Form changes; matter stays the same

2. 3 categories of beingNot, potential, actual

C. Nature and Change3. Cause of change

• All natural things behave according to their nature• Biological: inner driving force

• Four causes• Formal cause: properties that can change• Material cause: unchanging matter• Efficient cause: agent of causation• Final cause: goal, purpose (teleology)

• Examples:

• Statue • Newborn baby

(compare to atomists)

• The 4 elements: earth and water- down; air and fire- up

Hot

Cold

Dry Wet

D. Aristotle’s Stuff

Fire Air

Earth Water

• Reducible • Not geometrically

• Sensible qualities

Cold and dry =

Hot and dry = = Hot and wet

= Cold and wet

• Changeable

Natural places:

Earth and Water: down

Air and Fire: up

Fifth element (quintessence) = aether

• Cosmos completely filled with the aether

• No void (argument against void)

Other properties of the 4 elements

• Heavy or light• Earth heaviest – water – air - fire lightest• Heaviest falls to center

• Proof Earth is at center of universe• Proof Earth is spherical

• Lightest ascend to lunar sphere• If

unimpeded:

• Proof that Earth is stationary

• Physical reality:• Movements blocked• Mixtures of things

V. Aristotle’s Cosmology

• 2 (concentric) sphere model

• Problem with planetary motion

A. Eudoxus – Plato Model (student of Plato’s)

• Greeks not concerned with physical reality

• Greeks concerned with circles

Zodiac

Celestial equator

Solstice

Ecliptic

Equinox

Equinox

Solstice

The Celestial Sphere

V. Aristotle’s Cosmology

A. Origin of CosmosB. Properties of the

Universe1. Sphere divided into upper and lower regionsa. Celestial

region• Unchanging cycle

• Perfect circular motion• Filled with

aether• Celestial spheres

• Change and degeneration

• Unmoved mover (prime mover)

“in the whole range of time past … no change … of the outermost heavens”

“all motion involves a mover”b. Sublunar region

• Made up of the 4 elements

VI. MotionA. No motion without a mover

B. Two types of motion

1. Natural motion (internal force)

• Up: fire and air

• Towards natural place in a straight line

• Down: water and earth

2. Forced motion (external force)• Not in a straight

line• Motion stops when external force removed• Problem: projectiles

C. Celestial motion1. Unchanging

2. Perfect, circular motion3. Problem with seven wandering stars: sun, moon,

5 planets

• Retrograde motion of Mars

• Solution: each “star” given own sphere (Eudoxus)• 55 circles plus fixed star sphere

4. Ultimate cause of motion: unmoved (prime) mover

• Celestial spheres seek to emulate perfection of p.m.

VII. Biology

A. History of Animals1. Father of Biology, Zoology, Invertebrate Zoology

2. Over 500 species described

3. Begin with description, then explain

B. Classification

1. Red blooded

• Oviparous quadrupeds

• Viviparous quadrupeds

• Marine mammals

• Birds

• Fish

B. Classification

2. Bloodless

C. Souls (Internal organizing principles)

1. Nutritive soul- nourishment, growth, reproduction

• All that plants have

2. Sensitive soul – sensation and motion

• Animals have this plus nutritive soul

3. Rational soul

• Only humans have

• Souls do not survive death

D. Great Chain of Being (scala naturae)

• Implications for evolution

VIII. Achievements1. Nature of Stuff and how to know it2. Change and causation3. Structure of Cosmos4. Nature of deity (prime mover)5. Authority on disciplines

a. Terrestrial dynamicsb. Meteorologyc. Planetary astronomyd. Geologye. Physiologyf. Chemistryg. Biology

i. Zoology ii. intertidal marine

invertebrates6. Immediate problems: projectile and planetary motion

Rembrandt, Aristotle contemplating a bust of Homer

Raphael, The School of Athens