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 begin-
ning 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