Aristotle discusses there four types of scientific question or investigation, “whether X is”, “what X is”, “whether X is Y”, and “why X is Y”. His main claim is that the investigation what X is stands to the investigation whether X is, as the investigation why X is Y stands to the investigation whether X is Y. So in order to determine what X is, we must first investigate whether X is, and then, if the answer is yes, investigate why X is. An answer to why X is can be converted into a scientific a