• When both number and percentage are stated and compared in the same passage, pay extra attention to what can be said in the comparison. Simple math would solve some seemingly complex CR problems.
• Example: “Tom was paid twenty percent more this year than last year, while his administrative assistant, Sally, was paid only ten percent more. Therefore, Tom was paid more this year than Sally was.” What if Tom’s initial salary was less than half of that of Sally?
13. Parts vs. whole
• What is true for the parts might not be true for the whole: “Every part of this car is well built, so this car is well built.”
• What is true for the whole might not be true for the parts: “Apple sells only computers. So every Apple sales representative sells only computers.”
• What is true for some parts might not be true for the other parts: “May cat cleans herself daily. So all cats clean themselves daily.”
14. Past vs. future: “The bus has never been late. It will be on time today.”
15. Using the same word twice in the argument but with different meanings.
16. False choice
• When a passage argues A is the right choice because A and B are the only options and B won’t work, make sure A and B are the only options. If not, the argument relies on a false choice.
17. False analogy
• Analogies are always different than the claim they support. But false analogies are different in some important respect.
