TOPIC 2
THE ORIGIN OF SCIENCE IN ANCIENT GREECE

Readings - Wolpert, Chapter 3

 

INTRODUCTION

The origin of both science and western philosophy (as we define them today) arguably occurred in Greece about 600 BC. That implies that all of Egyptian, Mesopotamian, and the first 1000 years of Chinese civilization, occurred without a significant concept of science!

The Greeks tried to understand the world around them in terms of natural causes rather than supernatural or mythological causes. Early Greek thinkers considered both 'sense' (that which is material and of the external world) and 'thought' (that which is internal to the human mind). Thus, what we now view as two separate disciplines of philosophy and science started out as one inextricably intertwined field of thought. The term science was not actually applied to the discipline that studies the natural world until perhaps the 18th or 19th Century. Before then, it was viewed as natural philosophy (arguably a much more appropriate term).

At different times science has incorporated elements of mysticism, necromancy (~witchcraft), alchemy, philosophy, and religion. The boundaries between each of these disciplines was (and is) fuzzy to many people at different times of human history.

The peculiar nature of science is responsible for the fact that, unlike technology or religion, science originated only once in history - in Greece. This emphasizes how rare science is in human cultural history.

And yet, the time of Science's start also represents essentially the start of a whole family of world views centered on humans and their actual observable relationships with the world around them. Within 200 years of the year 500 BC, we see the start of all but two major eastern philosophy/religions, Bhuddism, Confucism, and Taoism. (The exceptions are arguably Hinduism and Shinto.) We similarly see the intertwined beginning of western philosophy and science together in Greece. Also, this time marks the beginning of history as we know it today. History seeks to understand human developments in terms of actual sequences of events and human actions rather than the role of gods. What is even more amazing is that the first western histories by Herodotus (The History) and Thuycidides (The Pelopponesian Wars) are virtually synchronous with the first eastern histories by Confucius (Spring and Autumn Annals, part of his six classics) and perhaps Sun Tzu (The Art of War).

 

THE START OF SCIENCE

The documented history of science begins in Ionia, Greece (westernmost Asia Minor) with Thales of Miletus (~585 BC). Thales tried to explain the world not in terms of myths but in more concrete terms, terms that might be subject to verification! He and other Greek philosophers had the conviction that there are laws controlling nature and that the laws are discoverable. For example, Anaximander of Miletus (~555 BC) hypothesized that thunderbolts are caused by wind motion and lightning the result of clouds splitting apart.

What were the cultural/historical factors which caused science and philosophy to start at this time and in this place? The two key factors were most likely: (1) the rise of democratic/oligarchic city states where citizens played a significant role in government through discussion and argument and (2) a broad increase in living standard for the middle class that gave them free time and wealth to contribute to government and explore education.

The earliest philosophers (pre-Socratics) 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.

The teachings and arguments of the early philosophers became 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 stopped amman 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.

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, and debate. Criticism and debate were perhaps the key elements that arose out of political and economic developments that led to a virtual explosion of early scientific ideas. The fact that human and natural philosophy were still so tightly intertwinned led to occasional 'animistic' explanations for natural processes. That is, human emotions were applied to the natural world. Thus,

Another factor that also may have been somewhat important in the development of early philosophy/science is the concommitant rise in literacy and writing (new Phoenician alphabet was simpler to use/teach than hyrogliphics or cunieform).

A question that is still unanswered today is why did it take so long for science to develop in the first place? Although some philosophers are amazed that it started at all!

 

SELECTED ELEMENTS OF ANCIENT SCIENCE
(~600 BC to 300 BC; Thales to Aristotle)

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, and mathematics. Below is a brief summary of selected initial ideas (more properly, theories) in astronomy, physics, and mathematics which we will follow as they develop into modern science. We will focus on three aspects of physics: the nature of motion (the action of forces), the nature of matter, and the nature of time. In the beginning, the nature of force/motion and matter were considered together as two integrated aspects of the same general problem.

 

Astronomy:

The earliest idea for a 'natural' explanation of the Earth's place in the universe was not far from mythological viewpoints (but without a supernatural component). Thales (~585 BC) thought that the Earth floated in water. The wave motion rocking the Earth caused earthquakes to occur.

Within a few decades Anaximander (~555 BC) argued that 'the Earth hangs freely, remaining where it is because it is equidistant from all things.' He viewed stars as rings of fire. The rings themselves 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 like a puncture in a vast celestial bucycle wheel of fire. He postulated three such rings for the Sun, Moon, and stars. The diameters of the rings ar e27, 18, and 9 times the diameter o fthe Earth the Earth itself being a flat-topped cylinder three times as broad as deep, at rest in the center of the rings. Eclipses occur when the holes through which the Sun and Moon are seen become blocked.

By the time of Aristotle (~350 BC), the ancient Greeks 'knew' that the Earth is a sphere. They deduced it from observations:
1) shape of Earth's shadow on the Moon during eclipses is always circular.
2) mast of ships are the last thing seen as they sail away from land.
3) the altitude (angle) to the polar star (North Star) changes systematically with latitude.

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.

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.

 

Elements of Physics ­ The Nature of Matter:

Thales of Miletus (~585 BC) arguably believed that the Earth and all matter are composed of varying forms of one fundamental material (element) - water. Water has observably different forms (solid, liquid, gas) which change from one form to another. Water fills the oceans and streams and its moisture is a key element in life. Anaximander, of Miletus (~555 BC) a colleague of Thales, thought that the primary element which makes up all matter is an indeterminate substance, the 'boundless'. Anaximenes of Miletus (~535 BC) thought that air was the fundamental substance of all things. Air condenses to form water, water condenses to form ice, and air forms from water by rarefaction as it evaporates or is boiled. Thus, condensation and rarefaction are important processes in the transformation of one material into another. (It is not clear, however, that these earliest thinkers really believed that all substances are actually made up of water or air, but perhaps that water or air were the initial origin of all natural materials.)

Aristotle's view (~350 BC), which basically endured until the Renaissance, was that all matter on Earth and the planets are composed of varying proportions of four elements - fire, water, air, earth. All matter can be transmuted from one form to another. He was the first to consider the properties of matter (combustable, meltable, water soluble, etc.) and catalogue a variety of substances (which he still thought were themselves composed of water, air, earth, and fire).

By contrast, Aristotle thought that the heavens (stars) are composed of one element, aether, which is eternal and immutable (unchanging).

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 created 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.

The Pythagoreans linked mathematics, philosophy, and religion into a world view that argued all matter consists of points or units in space, which taken together constitute a number. All things are numbers. Aristotle summarized their viewpoint as follows:
'The so-called Pythagoreans, who were the first to engage in mathematics, advanced this study, and being trained in it they thought that its principles were the principles of all things. But of these principles numbers are by nature the first, and in numbers they seemed to see resemblances to the things that are and come to be ­ more than fire and earth and water; and again they saw that the modifications and ratiosof the musical scales were expressible in numbers. Therefore, since all other things seemed in their whole nature to be modeled on numbers, and numbers seemed to be the first things in the whole of nature, they supposed that the elements of numbers to be the elements of all things, and t he whole heaven to be a musical scale and a number.'

 

Elements of Physics ­ The Nature of Motion (Forces):

Initial ideas of motion were separated into natural motion (an apple drops from a tree) and forced motion (throwing a ball). Early (pre-Socratic) philosophers attributed this to the fact that 'like things attract one another'.

Aristotle believed that the Earth is at rest ('If the Earth revolves around the Sun, why don't we feel it and fall off?) and all objects on Earth move naturally up or down depending on the predominant elements in each object. Things made mostly of air and fire move up, while objects made mostly of water and earth move down. All other movement requires special force (like throwing a ball).

One consequence of these views was the idea that objects fall at a speed proportional to their weight. Aristotle stated that
'if a certain weight move a certain distance in a certain time, a greater weight will move the same distance in a shorter time, and the proportion which the weights bear to one another, the times too wil bear to one another.'This idea lasted to the Renaissance even though observations were made that indicated the theory was not correct.
He also thought that speed will be inversely proportional to the density of the medium something falls through.
"By so much as air is thinner and more incorporeal than water, the object will move through one faster than through the other.'
Aristotle used these ideas to argue that there cannot be a true void, for in it the speeds of objects would be infinite.

Aristotle considered that objects 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) and that the natural movement of aether is circular rather than up/down as on Earth.

 

Elements of Physics ­ The Nature of Time:

The Greeks appreciated that time progressed, but did not comment much on its place in science or philosophy. Heraclitus of Ephesus (~500 BC) stated 'One cannot step in the same river, for fresh waters are always flowing in upon you. All things are in a state of flux.'

The more general issue of whether the universe changes or is unchanging was addressed primarily in the context of the nature of matter. 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. He stated that
'eyes and ears are bad witnesses for men if they have souls that cannot understand their language'. 'Do not let habit, born of experience, force you to let wander your heedless eye or echoing ear or tongue along this road, but judge by reason.'
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).'

Mathematics:

Thales (~585 BC) considered geometry as one element of the natural world. He was the first to define certain basic propositions:
- A circle is bisected by its diameter
- if two straight lines cut each other, opposite angles are equal
- any angle inscribed in a semi-circles is a right angle

Pythagoras of Samos (~550 BC) and later adherents of his ideas termed Pythagoreans greatly advanced mathematics, especially geometry. But, they carried their ideas into the realm of religion and formed a cult that was active in Magna Graecia in the 6th Century BC.

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), and (3) all right angles are equal.

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