In a present day conference on whether physics can provide valuable, genuine knowledge of the world, two people sit, listening attentively. Both people are deep in thought about their own theories on the subject. One, David Hume, shakes his head in outright denial. While most those in the conference are in agreement that physics can, indeed, provide genuine knowledge, he contends that physics and mathematics provide nothing at all. In fact, he thinks to himself, only things that can be divvied up into various sensory impressions provide genuine knowledge and, since mathematics and sciences cannot (particularly because they rely on causal relationships) they are essentially a waste of time.
Across the room is Immanuel Kant. At certain times of the conference he shakes his head in agreement; but in others he gives a quizzical, almost uncertain look, and gently shakes his head sideways. Many in the conference are neglecting to discuss the topic of sensory impressions, seemingly taking their beliefs for granted. Kant, on the other hand, like Hume, believes that sensory impressions are how we understand the world. However, unlike Hume, our mind shapes the world with these impressions; the mind arranges the sensations, transforms them into objects. After all, sensations cannot arrange themselves, yet humans constantly see a variety of sensory impressions as physical objects.
During an intermission in the conference, both Hume and Kant take a walk to reenergize their minds. Incidentally, they bump into each other. Both being intellectuals, they decide to take up an informal conversation on the subject themselves. Since the walk is short, they decide to give each other one chance to explain their thoughts and convince the other. They flip the coin to see who proposes first and then who responds. As per the coin flip, Hume starts and Kant will respond.
Hume: “First, there are two types of knowledge: ideas and impressions. While similar, they are in fact different. Impressions are obtained directly from the senses. That is to say, the pain of burning your hand is an impression as it is occurring, but when you recollect the memory it is an idea. In effect, impressions hold much more vivid senses since memories become increasingly vague. Furthermore, without impressions, there would be no ideas.
Because all ideas originate from a combination of impressions, the only genuine knowledge we can certain of is that which can be broken down into impressions. As an example, take a grey cloud. We can only think of a grey cloud because it is formed by previously acquiesced impressions of grey and cloud, which we then combine.
Therefore, without the corresponding impressions, any imagination cannot be of genuine knowledge. In physics this holds drastic consequences; let’s take the idea of causal relationships and the universal law that, “for every action, there is an equal but opposite reaction”, such as when two balls collide. In essence this implies two things....