Campbell had the idea of both moral and scientific reasoning. In his book, "The Philosophy of Rhetoric", the philosopher states four types of evidence that goes into reasoning. The first one is that reasoning comes from experience and how past experiences shape our sense of reason for present, and future reasoning. The second type of evidence is analogy, to analyze a situation we are able to get more of an understanding and view what needs to be done in the future to better an outcome. The third type of evidence is testimony. Testimony has to deal with written or oral communication. The very last is calculations of chances. Knowing that chance is not predictable a person can assume and use reason when it comes to other certain types of happenings.