Following Aristotle, Ockham asserts that human beings are born blank states: there are no innate certainties to be discovered in our minds. We learn by observing qualities in objects. Ockham’s version of empiricism is called “direct realism” because he denies that there is any intermediary between the perceiver and the world. (Note that direct realism should not be confused with metaphysical realism, which Ockham rejects, as discussed above.) Direct realism states that if you see an apple, its redness causes you to know that it is red. This may seem obvious, but it actually raises a problem that has led many empiricists, both in Ockham’s day and today, to reject direct realism.
As the French philosopher Peter Aureol (1275-1333) points out, the problem is that there are cases where we perceive something that is not really there. In optical illusions, hallucinations, and dreams, our perceptions are completely disconnected with the external world.
Representationalism is the version of empiricism designed to solve this problem. According to representationalists, human beings perceive the world through a mental mediary, or representation, known in the Middle Ages as the “intelligible species.” Normally, an apple causes an intelligible species of itself for us to perceive it through. In cases of optical illusions, hallucinations, and dreams, something else causes the intelligible species. The perception seems veridical to us because there is no difference in the intelligible species. Even before Peter Aureol, Thomas Aquinas advocated representationalism, and it soon became the dominant view.
The difficulty with representationalism, as the Irish philosopher George Berkeley (1685-1754) amply demonstrates, is that once you introduce an intermediary between the perceiver and the external world, you lose your justification for belief in the external world. If all of our ideas come through representations, how do we know what, if anything, is behind these representations? Something other than physical objects could be causing them. For example, God could be transmitting representations of physical objects to our minds without ever creating any physical objects at all—which is in fact what Berkeley came to believe. This view, known as idealism, is radically skeptical, and most philosophers prefer to avoid it.
Srila Prabhupada once said:
Therefore, in the Srimad-Bhagavatam it is said that this is the incarnation of God in this age. And who worships Him? The process is very simple. Just keep a picture of Lord Chaitanya with His associates.