Introduction to Philosophy by Jacques Maritain

Inspired by the Thomistic Revival called for by Leo XIII, Maritain relies heavily on Aristotle and St. Thomas Aquinas to shape a philosophy that, far from sectarian theology in disguise, is driven by reason and engages the modern world.

Origins of Philosophy

Primitive man was able to deduce some truths about the nature through common sense, though the great feat of philosophical knowledge was not easy to discover and in most cases was wound too closely with myth and religion.

The Greeks and Indians were the first to sucessfully isolate philosophy from religion, and only in Greece would the proper path to philosophical knowledge be fully uncovered.

Maritain chooses to zero in on the progression of Greek philosophy from Thales of Miletus (624-546) to Aristotle (384-322), as this period lays the foundation for all Western philosophy. This progression can be broken down into three epochs:

Formation (pre-Socratic)
Crisis (Sophists and Socrates)
Fruitful Maturity (Plato and Aristotle)

Formation

During this period philosophers such as Thales, Anaximenes (588-524), Heraclitus (540-475), and Anaximander (610-547) were searching for the material cause of all things. But unable to look much beyond the physical world, they chose things such as air, fire, water, or some fusion of all contraries called the apeiron (the infinite or boundless).

They believed that all things were active, living, and animate. Thales stated, all things "are full of gods." This doctrine is known as hylozoism.

Interestingly, evolutionism was also proposed during this time by Anaximander, who suggested that life began in the water and that humans evolved from fish-like creatures. Eventually, Empedocles of Arigentum (493-433) would expand on this earlier idea of evolutionism proposed by Anaximander, suggesting that living beings advanced through a process of trial and error, whereby only the fittest survived to reproduce.

Three other important "physicists" of this period were:

Heraclitus: Proposed that all things are in a state of flux, and that fire is the primary substance.
Democritus (470-361): Proposed that all things are made of indivisible particles called atoms.
Anaxagoras (500-428): Proposed that everything contains a portion of everything else, and that mind (nous) is the ordering principle of the universe. Which by itself is uninteresting, but would lead Aristotle to later discover the concept of first matter.

Also emerging in this period was Pythagoras (572-522), proposing that numbers and mathematical relations are the true reality behind all things. Aristotle critiqued their view, stating that instead of testing their hypotheses through observation of the physical world, they would instead impose their mathematical ideas onto reality and claiming "to assist God to fashion the universe."

The last covered is the Eleatic school, begun by Xenophanes of Colophon (570-?) but most famously represented by Parmenides of Elea (540-?). This is where the first discoveries of metaphysics were made and Parmenides formulated the law of non-contradiction.

Definitions

Evolutionism: The belief that all things evolve from simpler forms.
Hylozoism: The belief that all matter has life.
Law of Non-Contradiction: A thing cannot both be and not be at the same time and in the same respect.
Material Cause: That out of which a thing is made.
Materialistic Monism: The belief that all things are made of one material substance.

Quotes

Pythagoras who first invented the term philosophy (love of wisdom), observing that wisdom belongs in the strict sense to God alone, and for that reason not wishing to be called a wise man, but simply a friend or lover of wisdom.