interested in was nature study. He was not only the last of the great Greek
philosophers, he was Europe’s first great biologist.
Taking it to extremes, we could say that Plato was so engrossed in his
eternal forms, or “ideas,” that he took very little notice of the changes in
nature. Aristotle, on the other hand, was preoccupied with just these
changes—or with what we nowadays describe as natural processes.
To exaggerate even more, we could say that Plato turned his back on
the sensory world and shut his eyes to everything we see around us. (He
wanted to escape from the cave and look out over the eternal world of ideas!)
Aristotle did the opposite: he got down on all fours and studied frogs and fish,
anemones and poppies.
While Plato used his reason, Aristotle used his senses as well.
We find decisive differences between the two, not least in their writing.
Plato was a poet and mythologist; Aristotle’s writings were as dry and precise
as an encyclopedia. On the other hand, much of what he wrote was based on
up-to-the-minute field studies.
Records from antiquity refer to 170 titles supposedly written by Aristotle.
Of these, 47 are preserved. These are not complete books; they consist
largely of lecture notes. In his time, philosophy was still mainly an oral activity.
The significance of Aristotle in European culture is due not least to the
fact that he created the terminology that scientists use today. He was the
great organizer who founded and classified the various sciences.
Since Aristotle wrote on all the sciences, I will limit myself to some of the
most important areas. Now that I have told you such a lot about Plato, you
must start by hearing how Aristotle refuted Plato’s theory of ideas. Later we
will look at the way he formulated his own natural philosophy, since it was
Aristotle who summed up what the natural philosophers before him had said.
We’ll see how he categorizes our concepts and founds the discipline of Logic
as a science. And finally I’ll tell you a little about Aristotle’s view of man and
society.
No Innate Ideas
Like the philosophers before him, Plato wanted to find the eternal and
immutable in the midst of all change. So he found the perfect ideas that were
superior to the sensory world. Plato furthermore held that ideas were more
real than all the phenomena of nature. First came the idea “horse,” then came
all the sensory world’s horses trotting along like shadows on a cave wall. The
idea “chicken” came before both the chicken and the egg.
Aristotle thought Plato had turned the whole thing upside down. He
agreed with his teacher that the particular horse “flows” and that no horse
lives forever. He also agreed that the actual form of the horse is eternal and
immutable. But the “idea” horse was simply a concept that we humans had
formed after seeing a certain number of horses. The “idea” or “form” horse
thus had no existence of its own. To Aristotle, the “idea” or the “form” horse
was made up of the horse’s characteristics—which define what we today call
the horse species.
To be more precise: by “form” horse, Aristotle meant that which is
common to all horses. And here the metaphor of the gingerbread mold does
not hold up because the mold exists independently of the particular ginger-
bread cookies. Aristotle did not believe in the existence of any such molds or