set the white one in motion.”
“Yes, I remember.”
“But that very thing which Hume says we cannot prove is what Kant
makes into an attribute of human reason. The law of causality is eternal and
absolute simply because human reason perceives everything that happens as
a matter of cause and effect.”
“Again, I would have thought that the law of causality lay in the physical
world itself, not in our minds.”
“Kant’s philosophy states that it is inherent in us. He agreed with Hume
that we cannot know with certainty what the world is like ‘in itself.’ We can
only know what the world is like ‘for me’—or for everybody. Kant’s greatest
contribution to philosophy is the dividing line he draws between things in
themselves—das Ding an sich— and things as they appear to us.”
“I’m not so good at German.”
“Kant made an important distinction between ‘the thing in itself and ‘the
thing for me.’ We can never have certain knowledge of things ‘in themselves.’
We can only know how things ‘appear’ to us. On the other hand, prior to any
particular experience we can say something about how things will be
perceived by the human mind.”
“We can?”
“Before you go out in the morning, you cannot know what you will see or
experience during the day. But you can know that what you see and
experience will be perceived as happening in time and space. You can more-
over be confident that the law of cause and effect will apply, simply because
you carry it with you as part of your consciousness.”
“But you mean we could have been made differently?”
“Yes, we could have had a different sensory apparatus. And we could
have had a different sense or time and a different feeling about space. We
could even have been created in such a way that we would not go around
searching for the cause of things that happen around us.”
“How do you mean?”
“Imagine there’s a cat lying on the floor in the living room. A ball comes
rolling into the room. What does the cat do?”
“I’ve tried that lots of times. The cat will run after the ball.”
“All right. Now imagine that you were sitting in that same room. If you
suddenly see a ball come rolling in, would you also start running after it?”
“First, I would turn around to see where the ball came from.”
“Yes, because you are a human being, you will inevitably look for the
cause of every event, because the law of causality is part of your makeup.”
“So Kant says.”
“Hume showed that we can neither perceive nor prove natural laws. That
made Kant uneasy. But he believed he could prove their absolute validity by
showing that in reality we are talking about the laws of human cognition.”
“Will a child also turn around to see where the ball came from?”
“Maybe not. But Kant pointed out that a child’s reason is not fully
developed until it has had some sensory material to work with. It is altogether
senseless to talk about an empty mind.”
“No, that would be a very strange mind.”
“So now let’s sum up. According to Kant, there are two elements that
contribute to man’s knowledge of the world. One is the external conditions