TOPIC 3: The Origin of Science (and Philosophy) in Ancient Greece

1. TOPIC 3:The Origin of Science (and Philosophy) in Ancient Greece 500/600 BC (a key time period in human affairs)

2. Great Civilizations older than 500/600 BC • Egypt (3200-120 BC) • Sumeria (3200-1800 BC) • Hittite Empire (1900-1200 BC) • Minoan Empire (1900-1400 BC) • Mycenean Empire (1500-1200 BC) • Assyrian/Babylonian Empire (1800-600 BC) • China (Shang/Chou Dynasties; 1500-200 BC) • Maya/Inca Precursors (>1000 BC - 200 AD)

3. Several Great Beginnings(500/600 BC) • Science (Greece) • Western Philosophy (Greece) • History (Greece, China) • Bhuddaism (India) • Confucianism (China) • Taoism (China)

6. At The Beginning in Greece- Thales of Miletus (~585 BC) • Thales tried to explain human activity (‘thought’) and the natural world (’sense’) in concrete terms subject to verification and explainable by laws that are discoverable without recourse to gods/goddesses or mythology. • He also established mathematics as an integral part of science. • In actuality, all of these developments were lumped under the notion of philosophy. Within a hundred years, human philosophy and natural philosophy (science of the future) were somewhat distinct from one another.

7. Why and How did Philosophy Develop in Ancient Greece? • Lack of kingly rule allowed more people take part in democratic or oligarchic government. Discussion and debate were key elements in government; people needed training. • Rise of Middle Class living standards and wealth (not in the hands of rulers) let people contribute to government and explore education. • Another factor that also may have been somewhat important in the development of early philosophy/science is the rise in literacy and writing using a new Phoenician alphabet that was simpler to use/teach than hieroglyphics or cunieform.

8. What Did Early Greek Philosophers Do For a Living? • The earliest philosophers (pre-Socrates) were not full-time teachers. For example, Thales engaged in both business and political affairs and was regularly included with Solon in any list of the Seven Wise Men. • However, by the beginning of the 5th century BC, dozens of schools were set up by philosophers throughout the Greek world. The most famous schools were the Academy of Plato of Athens (~380 BC) and the Lyceum of Aristotle of Stagira (~350 BC), both in Athens. Topics taught include grammar, logic, ethics, poetry, music, physics, cosmology, mathematics.

9. Philosophers As Part of Society • The teachings and arguments of the early philosophers were an intrinsic part of the Greek culture/society. • Their arguments are commented on in the plays of Eurypides and Sophocles just as are the myths of the Greek gods. • One of Xenophanes’ poems tells the story of how Pythagoras (famous mathematician) stopped a man from beating a dog with the words: ‘Stop, do not beat him. It is the soul of a friend – I recognize his voice.’ This poem pokes fun at the Pythagorean theory of transmigration of souls.

10. How Did Early Greek Philosophers Do Science? • There was no single method by which early philosophers developed their ideas. • But, they did use key elements of what we now consider to be modern scientific research: • observation • catagorization • logic • rational criticism • debate • Criticism and debate were perhaps the key elements that arose out of political and economic developments. • The fact that human and natural philosophy were so tightly intertwined led to occasional ‘animistic’ explanations for natural processes. That is, human emotions were applied to the natural world.

11. An Unanswered Question:Why was science not developed before the Greeks? (or independently at different times and places?)

12. Some Initial Greek Ideas About Natural Philosophy (Science) • Greek natural philosophy quickly developed into four broad fields of study: • Elements of physics (including what we now consider chemistry, biology, and earth science) • Astronomy • Medicine • Mathematics • We will focus on astronomy, math, and three aspects of physics: • the nature of motion (the action of forces) • the nature of matter • the nature of time • Initially, the natures of force/motion and matter were considered together as two integrated aspects of the same general problem.

13. The Beginning of Astronomy - The Earth • Thales (~585 BC) thought that the Earth was flat and floated in water. The wave motion rocking the Earth caused earthquakes to occur. • Within a few decades, Anaximander (~555 BC) of Miletus argued that • ‘the Earth hangs freely, remaining where it is because it is equidistant from all things.’ • By the time of Aristotle (~350 BC) the Greeks knew the Earth was a sphere based on the following direct observations: • The Earth’s shadow on the moon during eclipse is arcuate • A ship’s mast is last to be seen in distance as a ship sails away • The altitude of the North Star changes systematically with latitude

14. The Beginning of Astronomy - The Sun, Moon, and Stars • Anaximander (~555 BC) viewed the stars as rings of fire. • The rings cannot be seen because they are surrounded by mist, but they have openings though which heavenly bodies appear: what we see as a star is a puncture in a vast celestial bicycle wheel of fire. • He postulated three rings for the Sun, Moon, and stars. The diameters of the rings are 27, 18, and 9 times the diameter of the Earth • Eclipses occur when the holes through which the Sun and Moon are seen become blocked. • Eudoxus of Knidus (~365 BC) developed a theory of an Earth-centered universe with all planets and stars embedded in a series of concentric spheres surrounding the Earth. Each sphere rotated about an axis embedded in a sphere that was farther way from the Earth.

15. The Beginning of Astronomy- The Zodiac • A special place must be reserved for the Zodiac, a series of 12 constellations that define an imaginary ‘oblique circle’ through the stars with the Earth at its center. This circle is the apparent orbit of the Sun. It is called the ecliptic because eclipses only occur when the Moon is at or near this line. • The ecliptic also defines the orbits of the five planets known to the ancients: Saturn, Jupiter, Mars, Venus, and Mercury. Planets looked like stars to the ancients, but they moved through the heavens like the Sun relative to the background stars of the Zodiac constellations.

17. The Nature of Matter • Aristotle’s view (~350 BC), which basically endured until the Renaissance, was that all matter on Earth is composed of varying proportions of four elements: • Fire • Water • Air • Earth • He thought that all matter can be transmuted from one form to another. • He was the first to consider the properties of matter (combustible, meltable, water soluble, etc.) • He was the first to catalogue a variety of substances (which he still thought were themselves composed of water, air, earth, and fire).

18. The Atomists • The ‘Atomists’ (led by Leucippus of Miletus (~435 BC) and Democritus of Abdera (~410 BC)) argued that the universe is composed of an infinite number of invisible particles called atoms with everything else being a void. The atoms differ in size and shape, but all have solidity and (usually) weight. Collisions between atoms create larger objects. Fire, water, air, and earth are all composed of atoms. • Zeno of Elea (~445 BC) argued against the notion of discrete particles and a void - he wanted both space and time to be continuous quantities rather than inherently discrete. Aristotle also did not believe in a void. However, Leucippus (~435 BC) and Parmenides of Elea (~480 BC) argued that a void must exist for movement to occur.

19. Motion on Earth • Aristotle's ideas on motion, related to the nature of matter, held sway for 1800 years.He classified all motion on Earth into three types: • Natural motion (by inanimate objects) • Forced or violent motion • Animate motion (living things) • All inanimate objects on Earth move naturally up or down depending on their relative proportion of the four elements (fire, air goes up; earth, water goes down) • One consequence of these views was the idea that objects fall at a speed proportional to their weight.

20. Motion of the Stars • Aristotle considered that stars in the heavens move naturally in circles and that the stars are immortal and unchanging. • He posited that the stars are made of aether, an immutable substance (separate from air, water, earth, and fire which have the ability to transform from one material to another) • He presumed that the natural movement of aether must be circular rather than up/down as on Earth.

21. Time • The Greeks knew of the existence of time but paid little attention to how it fit in with human or natural philosophy • ‘One cannot step in the same river, for fresh waters are always flowing in upon you. All things are in a state of flux.’ • A more general issue was whether the universe changes or is unchanging. Heraclitus (~500 BC) thought that ‘everything is subject to change (at one time or another)’. • By contrast, Parmenides (~480 BC) argued that nothing changes (or ‘comes into being’), the senses are unreliable recorders of the real world. • Empedocles of Akragas (~455 BC) represented a middle ground by stating that • ‘earth, wind, fire, and water all exist and have always existed, and they produce change by mixing with and separating from one another under the influence of two opposite forces (love and strife).’

22. Mathematics • Euclid (~300 BC) is often termed the Father of Geometry not because he originated it, which he didn’t, but because he was the first to organize knowledge of geometry into a series of five postulates (unprovable assumptions) and a series of resulting theorems. • Postulates include • (1) the diameter of a circle bisects it (from Thales) • (2) two points completely define a circle (one is the center, the other defines the radius) • (3) all right angles are equal

23. Pythagoreans • Pythagoras of Samos (~550 BC) and later adherents of his ideas termed Pythagoreans greatly advanced mathematics, especially geometry. • However, they combined philosophy and mathematics into a religion: • all mater consists of points/units in space • taken together, all objects are numbers • Zeno argued against them - he thought space and time are continuous rather than discrete