founded the Athenian school called the Lyceum. He was the
first philosopher to analyze the process whereby certain
propositions can be logically inferred to be true from
the fact that certain other propositions are true -- all
men are mortal; Socrates is a man; therefore, Socrates is
suggested that all substance in the universe was made up
of particles so minute that nothing smaller was possible.
He regarded those particles (atoms) as unchangeable and
indestructible, and as the only content of the universe
besides the very space in which they existed.
believed that all matter was composed of various
combinations and arrangements of four elements -- fire,
air, water, and earth -- and that the forces of Love and
Strife acted on those elements and caused them to mingle,
separate, and recombine.
believed that all substances come from water and will
eventually revert to water. He also made important
advances in the field of mathematics and was a careful
observer of the heavens.
believed that every difference in thinking must make a
difference to someone, somewhere. If two
theories differ, the difference becomes clear when we
know (1) how they differ over what the facts are, and (2)
the difference in our behavior if we believe that one or
the other is true.