through his senses. He held all other possibilities open. He rejected neither faith in Christianity nor faith in miracles. But both were matters of faith and not of knowledge or reason. You might say that with Hume’s philosophy, the final link between faith and knowledge was broken.”
“You say he didn’t deny that miracles can happen?”
“That didn’t mean that he believed in them, more the opposite. He made a point of the fact that people seemed to have a powerful need of what we today would call ‘supernatural’ happenings. The thing is that all the miracles you hear of have always happened in some far distant place or a long, long time ago. Actually, Hume only rejected miracles because he had never experienced any. But he had not experienced that they couldn’t happen either.”
“You’ll have to explain that.”
“According to Hume, a miracle is against the laws of nature. But it is meaningless to allege that we have experienced the laws of nature. We experience that a stone falls to the ground when we let go of it, and if it didn’t fall—well, then we experienced that.’1”
“I would say that was a miracle—or something supernatural.”
“So you believe there are two natures—a ‘natural’ and a ‘supernatural.’ Aren’t you on the way back to the rationalistic claptrap?”
“Maybe, but I still think the stone will fall to the ground every time I let go.”
“Why?”
“Now you’re being horrible.”
“I’m not horrible, Sophie. It’s never wrong for a philosopher to ask questions. We may be getting to the crux of Hume’s philosophy. Tell me how you can be so certain that the stone will always fall to the earth.”
“I’ve seen it happen so many times that I’m absolutely certain.”
“Hume would say that you have experienced a stone falling to the ground many times. But you have never experienced that it will always fall. It is usual to say that the stone falls to the ground because of the law of gravitation. But we have never experienced such a law. We have only experienced that things fall.”
“Isn’t that the same thing?”
“Not completely. You say you believe the stone will fall to the ground because you have seen it happen so many times. That’s exactly Hume’s point. You are so used to the one thing following the other that you expect the same to happen every time you let go of a stone. This is the way the concept of what we like to call ‘the unbreakable laws of nature’ arises.”
“Did he really mean it was possible that a stone would not fall?”
“He was probably just as convinced as you that it would fall every time he tried it. But he pointed out that he had not experienced why it happens.”
“Now we’re far away from babies and flowers again!”
“No, on the contrary. You are welcome to take children as Hume’s verification. Who do you think would be more surprised if the stone floated above the ground for an hour or two—you or a one-year-old child?”
“I guess I would.”
“Why?”
“Because I would know better than the child how unnatural it was.”
“And why wouldn’t the child think it was unnatural?”
“Because it hasn’t yet learned how nature behaves.”
“Or perhaps because nature hasn’t yet become a habit?”
“I see where you’re coming from. Hume wanted people to sharpen their awareness.”
“So now do the following exercise: let’s say you and a small child go to a magic show, where things are made to float in the air. Which of you would have the most fun?”
“I probably would.”
“And why would that be?”
“Because I would know how impossible it all is.”
“So... for the child it’s no fun to see the laws of nature being defied before it has learned what they are.”
“I guess that’s right.”
“And we are still at the crux of Hume’s philosophy of experience. He would have added that the child has not yet become a slave of the expectations of habit; he is thus the more open-minded of you two. I wonder if the child is not also the greater philosopher? He comes utterly without preconceived opinions. And that, my dear Sophie, is the philosopher’s most distinguishing virtue. The child perceives the world as it is, without putting more into things than he experiences.”
“Every time I feel prejudice I get a bad feeling.”
“When Hume discusses the force of habit, he concentrates on ‘the law of causation.’ This law establishes that everything that happens must have a cause. Hume used two billiard balls for his example. If you roll a black billiard ball against a white one that is at rest, what will the white one do?”
“If the black ball hits the white one, the white one will start to move.”
“I see, and why will it do that?”
“Because it was hit by the black one.”
“So we usually say that the impact of the black ball is the cause of the white ball’s starting to move. But remember now, we can only talk of what we have actually experienced.”
“I have actually experienced it lots of times. Joanna has a pool table in her basement.”
“Hume would say the only thing you have experienced is that the white ball begins to roll across the table. You have not experienced the actual cause of it beginning to roll. You have experienced that one event comes after the other, but you have not experienced that the other event happens because o/the first one.”
“Isn’t that splitting hairs?”
“No, it’s very central. Hume emphasized that the expectation of one thing following another does not lie in the things themselves, but in our mind. And expectation, as we have seen, is associated with habit. Going back to the child again, it would not have stared in amazement if when one billiard ball struck the other, both had remained perfectly motionless. When we speak of the ‘laws of nature’ or of ‘cause and effect,’ we are actually speaking of what we expect, rather than what is ‘reasonable.’ The laws of nature are neither reasonable nor unreasonable, they simply are. The expectation that the white billiard ball will move when it is struck by the black billiard ball is therefore not innate. We are not born with a set of expectations as to what the world is like or how things in the world behave. The world is like it is, and it’s something we get to know.”
“I’m beginning to feel as if we’re getting off the track again.”
“Not if our expectations cause us to jump to conclusions. Hume did not deny the existence of unbreakable ‘natural laws,’ but he held that because we are not in a position to experience the natural laws themselves, we can easily come to the wrong conclusions.”
“Like what?”
“Well, because I have seen a whole herd of black horses doesn’t mean that all horses are black.”
“No, of course not.”
“And although I have seen nothing but black crows in my life, it doesn’t mean that there’s no such thing as a white crow. Both for a philosopher and for a scientist it can be important not to reject the possibility of finding a white crow. You might almost say that hunting for ‘the white crow’ is science’s principal task.”
“Yes, I see.”
“In the question of cause and effect, there can be many people who imagine that lightning is the cause of thunder because the thunder comes after the lightning. The example is really not so different from the one with the billiard balls. But is lightning the cause of thunder?”
“Not really, because actually they both happen at the same time.”
“Both thunder and lightning are due to an electric discharge. So in reality a third factor causes them both.”
“Right.”
“An empiricist of our own century, Bertrand Russell, has provided a more grotesque example. A chicken which experiences every day that it gets fed when the farmer’s wife comes over to the chicken run will finally come to the conclusion that there is a causal link between the approach of the farmer’s wife and feed being put into its
