A reflection on causality The question that what defines caulsality has long been discussed since the ancient times. Aristotle has raised four kinds of causes, namely, material cause, formal cause, efficient cause and the purpose. In modern science, disciplines follow different academic traditions. Some focus on chronological sequence of events, while others mostly rely on statistical models. A graduate student may wonder where to start to deal with it. After all, they have to go through a long period to learn to analyze causes and build their theoretical basement. That is not easy, because the basement should be both rational and also fit for the them to do following researches.