Below are the most important philosophical thinkers and examples of their key ideas. Notice that the questions can all be grouped into "HOW", "WHY", "IF" and "WHAT" categories. Science has been succesful at answering the "HOW" questions, but the "WHY" questions have and always will be speculative (religious). The "IF" questions have expanded our capacity for abstract and imaginative thought (literary), and the "WHAT" questions have expanded our understanding of causality (cause & effect).

Introduction

Select the boxes below to view details

Homer (c. 750 BC - i.e. 8th Century)

Father of Religion. "Cosmic order is moral order. So we must live moral lives so as to fit into this order". The Ilyad and the Odyssey suggest a moral order.
Note: The search for a physical order (via scientific observation) came with Thales.

Hesiod (c. 750 BC )

Father of Economics.

Thales of Miletus (c. 624 — c. 546 B.C.)

First thinker to investigate the basic principles of matter. How is matter constructed? Thales believed the basic element was Water. He attempted to show that everything was unified by water, and not a collection of isolated phenomena. He is an empiricist ("all that we know comes from sense experience")

Anaximander (c. 610 – c. 546 BC)

He reasoned that a single common element (monism) was impossible, by proposing the principle of opposites: hot/cold; dry/wet; light/dark; male/female. For him, the cosmos was apeiron (undefinable).
Note: Modern science tells us that dark is a lack of light, not an opposite; cold is lack of heat; male and female are complementary, not opposite

Anaximines(c. 585 – c. 528 BCE)

Material monism: all of the world's objects are composed of a single element: Air. This was another attempt at finding the unifying causes of all events. He recognized different states of air (hot & dry or cold & wet) and so postulated a "quantitative" variation (different states) of the primary element.
He, as the above two Milesians, believed the world was flat.

Xenophanes (c. 570 – c. 475 BC)

Postulated a God that was abstract, universal, unchanging, immobile and always present (monotheism). He is more precisely a pandeist (creator deity became the universe and ceased to exist as a separate and conscius entity). This is similar to pantheism (belief that all reality is identical with divinity or that everything composes an all-encompassing, immnent god.

Pythagoras (c. 570 – c. 495 BC)

Everything has mathematical order.

Heraclitus (c. 535 – c. 475 BC)

Everything is change. Hence Fire is the primary element of the cosmos. But the world also has order (logos), so there is permanence and predictability.
This suggested to him that there are two aspects to everything in nature (like a convex/concave saucer).
The next question was: What causes matter and events and the way they change in the Universe?

Parmenides ( c. 515 BC)

Reality (what is) is one, plurality is illusory, change is impossible (see Zeno's paradox of Achilles and the tortoise), and existence is timeless and uniform. Truth is reached through abstract logical reasoning (rationalism). Thought alone can pass beyond the false appearances of sense experience and arrive at the knowledge of being and at the fundamental truth that "All is One".
Furthermore, there can be no creation, for being cannot come from non-being.

He founded the school of the Eleatics.

Anaxagoras (c. 510 – c. 428 BC)

The Universe is made of seeds of each basic substance (bone, skin, blood, muscle, hair, etc.). The order of all this multitude of seeds is cerated by nus, or cosmic (divine) mind. This is the beginning of theology, versus mythology. This is qualitative pluralism guided by teleology (i.e. a meaningful direction)

Empedocles (c. 490 – c. 430 BC)

Empedicles thought that the cosmos was made up of all the main elements (air, earth, fire and water) that integrate and disentegrate to create all things in the cormos. This is qualitative pluralism. He believed that species evolved through natural trial and error (the fittest survive). He also believed in love and hate between all substances.

Democritus (c. 460 – c. 370 BC)

He is a qualitative monist, i.e. indivisible and identical atoms combine in different ways. This is mechanistic, not teleological. Blind forces combining by chance to create forms. A life guided by understanding of the causal processes can guide us away from pain. Hence the importance of reason.

xx

xxxt.

xx

xxxt.

xx

xxxt.

xx

xxxt.

xx

x

x

x

x

x

x

x

x

xxxt.

x

x

x

x