Plato (427 BC - 347 BC)
Appeared in: Lecture 1,3.
Greek philosopher who was a student and follower of
Socrates
. He founded the Academy school in Athens. His works consisted of "dialogs"
between
Socrates
and others. Like
Socrates
, he was interested in moral, not natural philosophy. He believed
that the heads of government should be "philosopher kings" and developed
a course of study stressing abstract thought for their education in the
Republic. Plato advocated the "quadrivium" (the four math fields
of study in the liberal arts), which starts with arithmetic, then progresses
to plane geometry, solid geometry, and finally astronomy and harmonics.
Plato believed that knowledge was "forgotten" at birth, and could be remembered.
He saw the search for understanding as an attempt to gain pure knowledge,
or "forms." In Eikos Mythos (A Likely Story), he said that
cosmology
is, at best, a likely account. In Timaeus, he presented his
cosmology
,
which consisted of forms, particular objects, God the Craftsman,
absolute space, and brute matter. As a craftsman, God could not make
a perfect world from imperfect material.
Plato believed all substances to be composed of air, earth, fire, and water.
He believed in a spherical
Earth
which was the center of his universe, and a motion of planets along
crystalline spheres. Plato invented a theory of vision involving three
streams of light: one from the what is being seen, one from the eyes, and
one from the illuminating source. In keeping with his belief that philosophy
should be pursued for the attainment of pure knowledge, he proposed studying
astronomy as an exact mathematical science based on the assumption that motions
were regular and circular. He wanted to discover the truth behind appearances,
but believed that absolute truth could not be derived.
Plato also described the five regular solids, the
tetrahedron
, 
cube
,
octahedron
,
dodecahedron
,
and icosahedron
,
now known as the
Platonic solids
.
For more information:
Plato picture taken from
MacTutor History of Mathematics Archive
.
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