Causation is everywhere in life. Economics, law, medicine, physics, statistics, philosophy, religion, and many other disciplines are inseparable from the analysis of cause and effect. However, compared to other concepts such as statistical correlation, causality is very difficult to define. Using intuition, we can easily judge the causal relationship in daily life; however, it is often beyond the ability of ordinary people to accurately answer the question “What is causality?” in clear, unambiguous language.