In his essay, “A Supposition of He Knows Not What,” John Locke offers the
reader an intriguing view of substances and ideas. He argues for the existence
of substances in our world because there must logically be something greater
than the ideas and thoughts that occupy our minds. His argument for their
existence maintains that we cannot see substances in our realms, but we can
perceive them and note their effects on other things around us. Locke first
states that there are too many ideas in the world to stand alone. We cannot see
these ideas that form in our minds, but we know that the ideas we have cannot
persists as one single idea, because everything we think is “a complication of
many ideas together” (Reality 90). Since the simple ideas we have cannot exist
alone, there must be something larger behind them, and those, Locke asserts, are
substances. Locke maintains that we only see substances in our world as ideas,
for they are too complex for us to perceive. Because of the qualities of our
ideas, we are able to perceive that they exist. The only evidence we have for
this belief is that we can put together ideas on our own, and we can also put
together ideas about substances, therefore these substances must create our
ideas. We perceive substances as ideas, because they are too complicated for our
minds and far from our realm of existence. Therefore, Locke’s notion of
substances reverts back to Plato’s idea of a form: substances are things that
underlie all thought, that we cannot perceive on our own, but must exist in
another place for they form our foundations of thought and ideas.