Rationalism refers to a school of thought which prioritises reason as the main source of knowledge. It hold the belief that we can know things about the world through reasoning alone, without any physical, measurable evidence from the real world. Empiricism on the other hand holds the belief that we know things about the world through studying the world around us. This school of thought is associated most often with the natural sciences as it relies on measurable results as the grounding for our knowledge.