"When we dream, we feel we are experiencing reality. What separates our waking feelings from our dream feelings?
" 'When I consider this carefully, I find not a single property which with certainty separates the waking state from the dream,' writes Descartes. And he goes on: 'How can you be certain that your whole life is not a dream?' "
"Jeppe thought he had only been dreaming when he had slept in the Baron's bed."
"And when he was lying in the Baron's bed, he thought his life as a poor peasant was only a dream. So in the same way, Descartes ends up doubting absolutely everything. Many philosophers before him had reached the end of the road at that very point."
"So they didn't get very far."
"But Descartes tried to work forward from this zero point. He doubted everything, and that was the only thing he was certain of. But now something struck him: one thing had to be true, and that was that he doubted. When he doubted, he had to be thinking, and because he was thinking, it had to be certain that he was a thinking being. Or, as he himself expressed it: Cogito, ergo sum."
"Which means?"
"I think, therefore I am."
"I'm not surprised he realized that."
"Fair enough. But notice the intuitive certainty with which he suddenly perceives himself as a thinking being. Perhaps you now recall what Plato said, that what we grasp with our reason is more real than what we grasp with our senses. That's the way it was for Descartes. He perceived not only that he was a thinking /, he realized at the same time that this thinking / was more real than the material world which we perceive with our senses. And he went on. He was by no means through with his philosophical quest."
"What came next?"
"Descartes now asked himself if there was anything more he could perceive with the same intuitive certainty.
He came to the conclusion that in his mind he had a clear and distinct idea of a perfect entity. This was an idea he had always had, and it was thus self-evident to Descartes that such an idea could not possibly have come from himself. The idea of a perfect entity cannot have originated from one who was himself imperfect, he claimed. Therefore the idea of a perfect entity must have originated from that perfect entity itself, or in other words, from God. That God exists was therefore just as self-evident for Descartes as that a thinking being must exist."
"Now he was jumping to a conclusion. He was more cautious to begin with."
"You're right. Many people have called that his weak spot. But you say 'conclusion.' Actually it was not a question of proof. Descartes only meant that we all possess the idea of a perfect entity, and that inherent in that idea is the fact that this perfect entity must exist. Because a perfect entity wouldn't be perfect if it didn't exist. Neither would we possess the idea of a perfect entity if there were no perfect entity. For we are imperfect, so the idea of perfection cannot come from us. According to Descartes, the idea of God is innate, it is stamped on us from birth 'like the artisan's mark stamped on his product.' "
"Yes, but just because I possess the idea of a crocophant doesn't mean that the crocophant exists."
"Descartes would have said that it is not inherent in the concept of a crocophant that it exists. On the other hand, it is inherent in the concept of a perfect entity that such an entity exists. According to Descartes, this is just as certain as it is inherent in the idea of a circle that all points of the circle are equidistant from the center. You cannot have a circle that does not conform to this law. Nor can you have a perfect entity that lacks its most important property, namely, existence."
"That's an odd way of thinking."
"It is a decidedly rationalistic way of thinking. Descartes believed like Socrates and Plato that there is a connection between reason and being. The more self-evident a thing is to one's reason, the more certain it is that it exists."
"So far he has gotten to the fact that he is a thinking person and that there exists a perfect entity."
"Yes, and with this as his point of departure, he proceeds. In the question of all the ideas we have about outer reality--for example, the sun and the moon--there is the possibility that they are fantasies. But outer reality also has certain characteristics that we can perceive with our reason. These are the mathematical properties, or, in other words, the kinds of things that are measurable, such as length, breadth, and depth. Such 'quantitative' properties are just as clear and distinct to my reason as the fact that I am a thinking being. 'Qualitative' properties such as color, smell, and taste, on the other hand, are linked to our sense perception and as such do not describe outer reality."
"So nature is not a dream after all."
"No, and on that point Descartes once again draws upon our idea of the perfect entity. When our reason recognizes something clearly and distinctly--as is the case for the mathematical properties of outer reality--it must necessarily be so. Because a perfect God would not deceive us. Descartes claims 'God's guarantee' that whatever we perceive with our reason also corresponds to reality."
"Okay, so now he's found out he's a thinking being, God exists, and there is an outer reality."
"Ah, but the outer reality is essentially different from the reality of thought. Descartes now maintains that there are two different forms of reality--or two 'substances.' One substance is thought, or the 'mind,' the other is extension, or matter. The mind is purely conscious, it takes up no room in space and can therefore not be subdivided into smaller parts. Matter, however, is purely extension, it takes up room in space and can therefore always be subdivided into smaller and smaller parts-- but it has no consciousness. Descartes maintained that both substances originate from God, because only God himself exists independently of anything else. But al-though both thought and extension come from God, the two substances have no contact with each other. Thought is quite independent of matter, and conversely, the material processes are quite independent of thought."
"So he divided God's creation into two."
"Precisely. We say that Descartes is a dualist, which means that he effects a sharp division between the reality of thought and extended reality. For example, only man has a mind. Animals belong completely to extended reality. Their living and moving are accomplished me-chanically. Descartes considered an animal to be a kind of complicated automaton. As regards extended reality, he takes a thoroughly mechanistic view--exactly like the materialists."
"I doubt very much that Hermes is a machine or an automaton. Descartes couldn't have liked animals very much. And what about us?