Intro to Logic
18 November 2008
Five Canon’s by John Stuart Mills
John Stuart Mills, a popular philosopher of the nineteenth century, dramatically changed the way in which the British processed their thoughts. In his book, “The system of Logic” he discusses his five canons/methods of inductive reasoning; principles developed from gathered information. He used these methods to discover and prove why things happen. His methods are: the method of agreement, the method of difference, the joint method of agreement and difference, the method of residues and the method of concomitant variation.
His method of agreement at large depends on having many instances or occurrences that are different but of those differences having one common factor. For example, a manager at a diner hires a new waitress and every shift she works the cash register ends up significantly short. Later when the paper work is reviewed the manager sees that no other waitress has a short register. One may conclude that she was stealing money. However, the method of difference is the very opposite of agreement. It says that every instance that occurs is similar except in one instance where it is different. A good example of the method of difference is, the manager of a diner notices a huge increase in the sale of hamburgers. The diner recently changed the brand of burgers but nothing else. One may conclude that the brand change is the reason for increased sales. His third canon, called the joint method of agreement and difference is a combination of the first two already discussed. It puts together both the positives and negatives of a situation. It states that when analyzing two different occurrences, the instance that is alike in the first occurrence is the instance that makes the second occurrence different. For example, in the first occurrence there are two people who have black hair but nothing else in common. In the second...