eternal and immutable “patterns” behind the various phenomena we come
across in nature. This remarkable view is known as Plato’s theory of ideas.
True Knowledge
I’m sure you’ve been following me, Sophie dear. But you may be
wondering whether Plato was being serious. Did he really believe that forms
like these actually existed in a completely different reality?
He probably didn’t believe it literally in the same way for all his life, but in
some of his dialogues that is certainly how he means to be understood. Let us
try to follow his train of thought.
A philosopher, as we have seen, tries to grasp something that is eternal
and immutable. It would serve no purpose, for instance, to write a philosophic
treatise on the existence of a particular soap bubble. Partly because one
would hardly have time to study it in depth before it burst, and partly because
it would probably be rather difficult to find a market for a philosophic treatise
on something nobody has ever seen, and which only existed for five seconds.
Plato believed that everything we see around us in nature, everything
tangible, can be likened to a soap bubble, since nothing that exists in the
world of the senses is lasting. We know, of course, that sooner or later every
human being and every animal will die and decompose. Even a block of
marble changes and gradually disintegrates. (The Acropolis is falling into ruin,
Sophie! It is a scandal, but that’s the way it is.) Plato’s point is that we can
never have true knowledge of anything that is in a constant state of change.
We can only have opinions about things that belong to the world of the
senses, tangible things. We can only have true knowledge of things that can
be understood with our reason.
All right, Sophie, I’ll explain it more clearly: a gingerbread man can be so
lopsided after all that baking that it can be quite hard to see what it is meant to
be. But having seen dozens of gingerbread men that were more or less
successful, I can be pretty sure what the cookie mold was like. I can guess,
even though I have never seen it. It might not even be an advantage to see
the actual mold with my own eyes because we cannot always trust the
evidence of our senses. The faculty of vision can vary from person to person.
On the other hand, we can rely on what our reason tells us because that is the
same for everyone.
If you are sitting in a classroom with thirty other pupils, and the teacher
asks the class which color of the rainbow is the prettiest, he will probably get a
lot of different answers. But if he asks what 8 times 3 is, the whole class will—
we hope—give the same answer. Because now reason is speaking and
reason is, in a way, the direct opposite of “thinking so” or “feeling.” We could
say that reason is eternal and universal precisely because it only expresses
eternal and universal states.
Plato found mathematics very absorbing because mathematical states
never change. They are therefore states we can have true knowledge of. But
here we need an example.
Imagine you find a round pinecone out in the woods. Perhaps you say
you “think” it looks completely round, whereas Joanna insists it is a bit
flattened on one side. (Then you start arguing about it!) But you cannot have
true knowledge of anything you can perceive with your eyes. On the other
hand you can say with absolute certainty that the sum of the angles in a circle