"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 that we cannot know of before we have perceived them through the senses. We can call this the material of knowledge. The other is the internal conditions in man himself--such as the perception of events as happening in time and space and as processes conforming to an unbreakable law of causality. We can call this the form of knowledge."
Alberto and Sophie remained seated for a while gazing out of the window. Suddenly Sophie saw a little girl between the trees on the opposite side of the lake.
"Look!" said Sophie. "Who's that?"
"I'm sure I don't know."
The girl was only visible for a few seconds, then she was gone. Sophie noticed that she was wearing some kind of red hat.
"We shall under no circumstances let ourselves be distracted."
"Go on, then."
"Kant believed that there are clear limits to what we can know. You could perhaps say that the mind's 'glasses' set these limits."
"In what way?"
"You remember that philosophers before Kant had discussed the really 'big' questions--for instance, whether man has an immortal soul, whether there is a God, whether nature consists of tiny indivisible particles, and whether the universe is finite or infinite."
"Yes."
"Kant believed there was no certain knowledge to be obtained on these questions. Not that he rejected this type of argument. On the contrary. If he had just brushed these questions aside, he could hardly have been called a philosopher."
"What did he do?"
"Be patient. In such great philosophical questions, Kant believed that reason operates beyond the limits of what we humans can comprehend. At the same time, there is in our nature a basic desire to pose these same questions. But when, for example, we ask whether the universe is finite or infinite, we are asking about a totality of which we ourselves are a tiny part. We can therefore never completely know this totality."
"Why not?"
"When you put the red glasses on, we demonstrated that according to Kant there are two elements that contribute to our knowledge of the world."
"Sensory perception and reason."
"Yes, the material of our knowledge comes to us through the senses, but this material must conform to the attributes of reason. For example, one of the attributes of reason is to seek the cause of an event."
"Like the ball rolling across the floor."
"If you like. But when we wonder where the world came from--and then discuss possible answers--reason is in a sense 'on hold.' For it has no sensory material to process, no experience to make use of, because we have never experienced the whole of the great reality that we are a tiny part of."
"We are--in a way--a tiny part of the ball that comes rolling across the floor. So we can't know where it came from."
"But it will always be an attribute of human reason to ask where the ball comes from. That's why we ask and ask, we exert ourselves to the fullest to find answers to all the deepest questions. But we never get anything firm to bite on; we never get a satisfactory answer because reason is not locked on."
"I know exactly how that feels, thank you very much."
"In such weighty questions as to the nature of reality, Kant showed that there will always be two contrasting viewpoints that are equally likely or unlikely, depending on what our reason tells us."
"Examples, please."
"It is just as meaningful to say that the world must have had a beginning in time as to say that it had no such beginning. Reason cannot decide between them. We can allege that the world has always existed, but con anything always have existed if there was never any beginning?